6.09HEADmaster

1 files changed, 0 insertions, 1983 deletions

diff --git a/hacks/glx/hypertorus.c b/hacks/glx/hypertorus.c
deleted file mode 100644
index 8adf5d7..0000000
--- a/hacks/glx/hypertorus.c
+++ /dev/null
@@ -1,1983 +0,0 @@
-/* hypertorus --- Shows a hypertorus that rotates in 4d */
-
-#if 0
-static const char sccsid[] = "@(#)hypertorus.c  1.2 05/09/28 xlockmore";
-#endif
-
-/* Copyright (c) 2003-2021 Carsten Steger <carsten@mirsanmir.org>. */
-
-/*
- * Permission to use, copy, modify, and distribute this software and its
- * documentation for any purpose and without fee is hereby granted,
- * provided that the above copyright notice appear in all copies and that
- * both that copyright notice and this permission notice appear in
- * supporting documentation.
- *
- * This file is provided AS IS with no warranties of any kind.  The author
- * shall have no liability with respect to the infringement of copyrights,
- * trade secrets or any patents by this file or any part thereof.  In no
- * event will the author be liable for any lost revenue or profits or
- * other special, indirect and consequential damages.
- *
- * REVISION HISTORY:
- * C. Steger - 03/05/18: Initial version
- * C. Steger - 05/09/28: Added the spirals appearance mode
- *                       and trackball support
- * C. Steger - 07/01/23: Improved 4d trackball support
- * C. Steger - 09/08/22: Removed check-config.pl warnings
- * C. Steger - 20/01/11: Added the changing colors mode
- * C. Steger - 20/05/18: Added per-fragment shading
- * C. Steger - 20/07/26: Make the shader code work under maxOS
- * C. Steger - 20/11/19: Remove all unnecessary global variables
- * C. Steger - 20/12/06: Moved all GLSL support code into glsl-utils.[hc]
- * C. Steger - 20/12/30: Make the shader code work under iOS
- */
-
-/*
- * This program shows the Clifford torus as it rotates in 4d.  The
- * Clifford torus is a torus lies on the "surface" of the hypersphere
- * in 4d.  The program projects the 4d torus to 3d using either a
- * perspective or an orthographic projection.  Of the two
- * alternatives, the perspective projection looks much more appealing.
- * In orthographic projections the torus degenerates into a doubly
- * covered cylinder for some angles.  The projected 3d torus can then
- * be projected to the screen either perspectively or
- * orthographically.
- *
- * There are three display modes for the torus: mesh (wireframe),
- * solid, or transparent.  Furthermore, the appearance of the torus
- * can be as a solid object or as a set of see-through bands or
- * see-through spirals.  Finally, the colors with with the torus is
- * drawn can be set to one-sided, two-sided, or to a color wheel.  The
- * colors can be static or changing dynamically.  In one-sided color
- * mode, the torus is drawn with the same color on the inside and the
- * outside.  In two-sided color mode, the torus is drawn with red on
- * the outside and green on the inside if static colors are used.  If
- * changing colors are used, dynamically varying complementary colors
- * are used for the two sides.  This mode enables you to see that the
- * 3d projection of the torus turns inside-out as it rotates in 4d.
- * The color wheel mode draws the torus with a fully saturated color
- * wheel.  If changing colors are used, the colors of the color wheel
- * are varying dynamically.  The color wheel mode gives a very nice
- * effect when combined with the see-through bands or see-through
- * spirals mode.
- *
- * Finally, the rotation speed for each of the six planes around which
- * the torus rotates can be chosen.
- *
- * This program is inspired by Thomas Banchoff's book "Beyond the
- * Third Dimension: Geometry, Computer Graphics, and Higher
- * Dimensions", Scientific American Library, 1990.
- */
-
-#ifndef M_PI
-#define M_PI 3.14159265358979323846
-#endif
-
-#define DISP_WIREFRAME             0
-#define DISP_SURFACE               1
-#define DISP_TRANSPARENT           2
-
-#define APPEARANCE_SOLID           0
-#define APPEARANCE_BANDS           1
-#define APPEARANCE_SPIRALS         2
-
-#define COLORS_ONESIDED            0
-#define COLORS_TWOSIDED            1
-#define COLORS_COLORWHEEL          2
-
-#define DISP_3D_PERSPECTIVE        0
-#define DISP_3D_ORTHOGRAPHIC       1
-
-#define DISP_4D_PERSPECTIVE        0
-#define DISP_4D_ORTHOGRAPHIC       1
-
-#define DEF_DISPLAY_MODE           "surface"
-#define DEF_APPEARANCE             "bands"
-#define DEF_COLORS                 "colorwheel"
-#define DEF_CHANGE_COLORS          "False"
-#define DEF_PROJECTION_3D          "perspective"
-#define DEF_PROJECTION_4D          "perspective"
-#define DEF_SPEEDWX                "1.1"
-#define DEF_SPEEDWY                "1.3"
-#define DEF_SPEEDWZ                "1.5"
-#define DEF_SPEEDXY                "1.7"
-#define DEF_SPEEDXZ                "1.9"
-#define DEF_SPEEDYZ                "2.1"
-
-
-/* For some strange reason, the color buffer must be initialized
-   and used on macOS. Otherwise one- and two-sided lighting will
-   not work. */
-#if (defined(HAVE_COCOA) || defined(__APPLE__)) && !defined(HAVE_IPHONE)
-#define VERTEXATTRIBARRAY_WORKAROUND
-#endif
-
-
-
-#ifdef STANDALONE
-# define DEFAULTS           "*delay:      25000 \n" \
-                            "*showFPS:    False \n" \
-                            "*prefersGLSL: True \n" \
-
-# define release_hypertorus 0
-# include "xlockmore.h"         /* from the xscreensaver distribution */
-#else  /* !STANDALONE */
-# include "xlock.h"             /* from the xlockmore distribution */
-#endif /* !STANDALONE */
-
-#ifdef USE_GL
-
-#include "glsl-utils.h"
-#include "gltrackball.h"
-
-
-#ifdef USE_MODULES
-ModStruct   hypertorus_description =
-{"hypertorus", "init_hypertorus", "draw_hypertorus", NULL,
- "draw_hypertorus", "change_hypertorus", NULL, &hypertorus_opts,
- 25000, 1, 1, 1, 1.0, 4, "",
- "Shows a hypertorus rotating in 4d", 0, NULL};
-
-#endif /* USE_MODULES */
-
-
-static char *mode;
-static int display_mode;
-static char *appear;
-static int appearance;
-static int num_spirals;
-static char *color_mode;
-static int colors;
-static Bool change_colors;
-static char *proj_3d;
-static int projection_3d;
-static char *proj_4d;
-static int projection_4d;
-static float speed_wx;
-static float speed_wy;
-static float speed_wz;
-static float speed_xy;
-static float speed_xz;
-static float speed_yz;
-
-static const float offset4d[4] = {  0.0,  0.0,  0.0,  2.0 };
-static const float offset3d[4] = {  0.0,  0.0, -2.0,  0.0 };
-
-
-static XrmOptionDescRec opts[] =
-{
-  {"-mode",            ".displayMode",  XrmoptionSepArg, 0 },
-  {"-wireframe",       ".displayMode",  XrmoptionNoArg,  "wireframe" },
-  {"-surface",         ".displayMode",  XrmoptionNoArg,  "surface" },
-  {"-transparent",     ".displayMode",  XrmoptionNoArg,  "transparent" },
-  {"-appearance",      ".appearance",   XrmoptionSepArg, 0 },
-  {"-solid",           ".appearance",   XrmoptionNoArg,  "solid" },
-  {"-bands",           ".appearance",   XrmoptionNoArg,  "bands" },
-  {"-spirals-1",       ".appearance",   XrmoptionNoArg,  "spirals-1" },
-  {"-spirals-2",       ".appearance",   XrmoptionNoArg,  "spirals-2" },
-  {"-spirals-4",       ".appearance",   XrmoptionNoArg,  "spirals-4" },
-  {"-spirals-8",       ".appearance",   XrmoptionNoArg,  "spirals-8" },
-  {"-spirals-16",      ".appearance",   XrmoptionNoArg,  "spirals-16" },
-  {"-onesided",        ".colors",       XrmoptionNoArg,  "onesided" },
-  {"-twosided",        ".colors",       XrmoptionNoArg,  "twosided" },
-  {"-colorwheel",      ".colors",       XrmoptionNoArg,  "colorwheel" },
-  {"-change-colors",   ".changeColors", XrmoptionNoArg,  "on"},
-  {"+change-colors",   ".changeColors", XrmoptionNoArg,  "off"},
-  {"-perspective-3d",  ".projection3d", XrmoptionNoArg,  "perspective" },
-  {"-orthographic-3d", ".projection3d", XrmoptionNoArg,  "orthographic" },
-  {"-perspective-4d",  ".projection4d", XrmoptionNoArg,  "perspective" },
-  {"-orthographic-4d", ".projection4d", XrmoptionNoArg,  "orthographic" },
-  {"-speed-wx",        ".speedwx",      XrmoptionSepArg, 0 },
-  {"-speed-wy",        ".speedwy",      XrmoptionSepArg, 0 },
-  {"-speed-wz",        ".speedwz",      XrmoptionSepArg, 0 },
-  {"-speed-xy",        ".speedxy",      XrmoptionSepArg, 0 },
-  {"-speed-xz",        ".speedxz",      XrmoptionSepArg, 0 },
-  {"-speed-yz",        ".speedyz",      XrmoptionSepArg, 0 }
-};
-
-static argtype vars[] =
-{
-  { &mode,          "displayMode",  "DisplayMode",  DEF_DISPLAY_MODE,  t_String },
-  { &appear,        "appearance",   "Appearance",   DEF_APPEARANCE,    t_String },
-  { &color_mode,    "colors",       "Colors",       DEF_COLORS,        t_String },
-  { &change_colors, "changeColors", "ChangeColors", DEF_CHANGE_COLORS, t_Bool },
-  { &proj_3d,       "projection3d", "Projection3d", DEF_PROJECTION_3D, t_String },
-  { &proj_4d,       "projection4d", "Projection4d", DEF_PROJECTION_4D, t_String },
-  { &speed_wx,      "speedwx",      "Speedwx",      DEF_SPEEDWX,       t_Float},
-  { &speed_wy,      "speedwy",      "Speedwy",      DEF_SPEEDWY,       t_Float},
-  { &speed_wz,      "speedwz",      "Speedwz",      DEF_SPEEDWZ,       t_Float},
-  { &speed_xy,      "speedxy",      "Speedxy",      DEF_SPEEDXY,       t_Float},
-  { &speed_xz,      "speedxz",      "Speedxz",      DEF_SPEEDXZ,       t_Float},
-  { &speed_yz,      "speedyz",      "Speedyz",      DEF_SPEEDYZ,       t_Float}
-};
-
-ENTRYPOINT ModeSpecOpt hypertorus_opts =
-{sizeof opts / sizeof opts[0], opts, sizeof vars / sizeof vars[0], vars, NULL};
-
-
-/* Color change speeds */
-#define DRHO    0.7
-#define DSIGMA  1.1
-#define DTAU    1.7
-
-/* Number of subdivisions of the surface */
-#define NUMU 64
-#define NUMV 64
-
-typedef struct {
-  GLint      WindH, WindW;
-  GLXContext *glx_context;
-  /* 4D rotation angles */
-  float alpha, beta, delta, zeta, eta, theta;
-  /* Color rotation angles */
-  float rho, sigma, tau;
-  /* Aspect ratio of the current window */
-  float aspect;
-  /* Trackball states */
-  trackball_state *trackballs[2];
-  int current_trackball;
-  Bool button_pressed;
-  float speed_scale;
-#ifdef HAVE_GLSL
-  GLfloat uv[(NUMU+1)*(NUMV+1)][2];
-  GLfloat col[(NUMU+1)*(NUMV+1)][4];
-  GLuint indices[4*NUMU*NUMV];
-  Bool use_shaders, buffers_initialized;
-  GLuint shader_program;
-  GLint vertex_uv_index, color_index;
-  GLint mat_rot_index, mat_p_index, bool_persp_index;
-  GLint off4d_index, off3d_index, draw_lines_index;
-  GLint glbl_ambient_index, lt_ambient_index;
-  GLint lt_diffuse_index, lt_specular_index;
-  GLint lt_direction_index, lt_halfvect_index;
-  GLint front_ambient_index, back_ambient_index;
-  GLint front_diffuse_index, back_diffuse_index;
-  GLint specular_index, shininess_index;
-  GLuint vertex_uv_buffer;
-  GLuint color_buffer, indices_buffer;
-  GLint ni, ne, nt;
-#endif /* HAVE_GLSL */
-} hypertorusstruct;
-
-static hypertorusstruct *hyper = (hypertorusstruct *) NULL;
-
-
-
-#ifdef HAVE_GLSL
-
-/* The GLSL versions that correspond to different versions of OpenGL. */
-static const GLchar *shader_version_2_1 =
-  "#version 120\n";
-static const GLchar *shader_version_3_0 =
-  "#version 130\n";
-static const GLchar *shader_version_3_0_es =
-  "#version 300 es\n"
-  "precision highp float;\n"
-  "precision highp int;\n";
-
-/* The vertex shader code is composed of code fragments that depend on
-   the OpenGL version and code fragments that are version-independent.
-   They are concatenated by glsl_CompileAndLinkShaders in the function
-   init_glsl(). */
-static const GLchar *vertex_shader_attribs_2_1 =
-  "attribute vec2 VertexUV;\n"
-  "attribute vec4 VertexColor;\n"
-  "\n"
-  "varying vec3 Normal;\n"
-  "varying vec4 Color;\n"
-  "\n";
-static const GLchar *vertex_shader_attribs_3_0 =
-  "in vec2 VertexUV;\n"
-  "in vec4 VertexColor;\n"
-  "\n"
-  "out vec3 Normal;\n"
-  "out vec4 Color;\n"
-  "\n";
-static const GLchar *vertex_shader_main =
-  "uniform mat4 MatRot4D;\n"
-  "uniform mat4 MatProj;\n"
-  "uniform bool BoolPersp;\n"
-  "uniform vec4 Offset4D;\n"
-  "uniform vec4 Offset3D;\n"
-  "\n"
-  "void main (void)\n"
-  "{\n"
-  "  vec3 p, pu, pv;\n"
-  "  float su = sin(VertexUV.x)\n;"
-  "  float cu = cos(VertexUV.x)\n;"
-  "  float sv = sin(VertexUV.y)\n;"
-  "  float cv = cos(VertexUV.y)\n;"
-  "  vec4 xx = vec4(cu,su,cv,sv);"
-  "  vec4 xxu = vec4(-su,cu,0.0,0.0);"
-  "  vec4 xxv = vec4(0.0,0.0,-sv,cv);"
-  "  vec4 x = MatRot4D*xx+Offset4D;\n"
-  "  vec4 xu = MatRot4D*xxu;\n"
-  "  vec4 xv = MatRot4D*xxv;\n"
-  "  if (BoolPersp)\n"
-  "  {\n"
-  "    vec3 r = x.xyz;\n"
-  "    float s = x.w;\n"
-  "    float t = s*s;\n"
-  "    p = r/s+Offset3D.xyz;\n"
-  "    pu = (s*xu.xyz-r*xu.w)/t;\n"
-  "    pv = (s*xv.xyz-r*xv.w)/t;\n"
-  "  }\n"
-  "  else\n"
-  "  {\n"
-  "    p = x.xyz/1.5f+Offset3D.xyz;\n"
-  "    pu = xu.xyz;\n"
-  "    pv = xv.xyz;\n"
-  "  }\n"
-  "  vec4 Position = vec4(p,1.0);\n"
-  "  Normal = normalize(cross(pu,pv));\n"
-  "  gl_Position = MatProj*Position;\n"
-  "  Color = VertexColor;\n"
-  "}\n";
-
-/* The fragment shader code is composed of code fragments that depend on
-   the OpenGL version and code fragments that are version-independent.
-   They are concatenated by glsl_CompileAndLinkShaders in the function
-   init_glsl_glsl(). */
-static const GLchar *fragment_shader_attribs_2_1 =
-  "varying vec3 Normal;\n"
-  "varying vec4 Color;\n"
-  "\n";
-static const GLchar *fragment_shader_attribs_3_0 =
-  "in vec3 Normal;\n"
-  "in vec4 Color;\n"
-  "\n"
-  "out vec4 FragColor;\n"
-  "\n";
-static const GLchar *fragment_shader_main =
-  "uniform bool DrawLines;\n"
-  "uniform vec4 LtGlblAmbient;\n"
-  "uniform vec4 LtAmbient, LtDiffuse, LtSpecular;\n"
-  "uniform vec3 LtDirection, LtHalfVector;\n"
-  "uniform vec4 MatFrontAmbient, MatBackAmbient;\n"
-  "uniform vec4 MatFrontDiffuse, MatBackDiffuse;\n"
-  "uniform vec4 MatSpecular;\n"
-  "uniform float MatShininess;\n"
-  "\n"
-  "void main (void)\n"
-  "{\n"
-  "  vec4 color;\n"
-  "  if (DrawLines)\n"
-  "  {\n"
-  "    color = Color;\n"
-  "  }\n"
-  "  else\n"
-  "  {\n"
-  "    vec3 normalDirection;\n"
-  "    vec4 ambientColor, diffuseColor, sceneColor;\n"
-  "    vec4 ambientLighting, diffuseReflection, specularReflection;\n"
-  "    float ndotl, ndoth, pf;\n"
-  "    \n"
-  "    if (gl_FrontFacing)\n"
-  "    {\n"
-  "      normalDirection = normalize(Normal);\n"
-  "      sceneColor = Color*MatFrontAmbient*LtGlblAmbient;\n"
-  "      ambientColor = Color*MatFrontAmbient;\n"
-  "      diffuseColor = Color*MatFrontDiffuse;\n"
-  "    }\n"
-  "    else\n"
-  "    {\n"
-  "      normalDirection = -normalize(Normal);\n"
-  "      sceneColor = Color*MatBackAmbient*LtGlblAmbient;\n"
-  "      ambientColor = Color*MatBackAmbient;\n"
-  "      diffuseColor = Color*MatBackDiffuse;\n"
-  "    }\n"
-  "    \n"
-  "    ndotl = max(0.0,dot(normalDirection,LtDirection));\n"
-  "    ndoth = max(0.0,dot(normalDirection,LtHalfVector));\n"
-  "    if (ndotl == 0.0)\n"
-  "      pf = 0.0;\n"
-  "    else\n"
-  "      pf = pow(ndoth,MatShininess);\n"
-  "    ambientLighting = ambientColor*LtAmbient;\n"
-  "    diffuseReflection = LtDiffuse*diffuseColor*ndotl;\n"
-  "    specularReflection = LtSpecular*MatSpecular*pf;\n"
-  "    color = (sceneColor+ambientLighting+diffuseReflection+\n"
-  "             specularReflection);\n"
-  "  }\n";
-static const GLchar *fragment_shader_out_2_1 =
-  "  gl_FragColor = clamp(color,0.0,1.0);\n"
-  "}\n";
-static const GLchar *fragment_shader_out_3_0 =
-  "  FragColor = clamp(color,0.0,1.0);\n"
-  "}\n";
-
-#endif /* HAVE_GLSL */
-
-
-
-/* Add a rotation around the wx-plane to the matrix m. */
-static void rotatewx(float m[4][4], float phi)
-{
-  float c, s, u, v;
-  int i;
-
-  phi *= M_PI/180.0;
-  c = cos(phi);
-  s = sin(phi);
-  for (i=0; i<4; i++)
-  {
-    u = m[i][1];
-    v = m[i][2];
-    m[i][1] = c*u+s*v;
-    m[i][2] = -s*u+c*v;
-  }
-}
-
-
-/* Add a rotation around the wy-plane to the matrix m. */
-static void rotatewy(float m[4][4], float phi)
-{
-  float c, s, u, v;
-  int i;
-
-  phi *= M_PI/180.0;
-  c = cos(phi);
-  s = sin(phi);
-  for (i=0; i<4; i++)
-  {
-    u = m[i][0];
-    v = m[i][2];
-    m[i][0] = c*u-s*v;
-    m[i][2] = s*u+c*v;
-  }
-}
-
-
-/* Add a rotation around the wz-plane to the matrix m. */
-static void rotatewz(float m[4][4], float phi)
-{
-  float c, s, u, v;
-  int i;
-
-  phi *= M_PI/180.0;
-  c = cos(phi);
-  s = sin(phi);
-  for (i=0; i<4; i++)
-  {
-    u = m[i][0];
-    v = m[i][1];
-    m[i][0] = c*u+s*v;
-    m[i][1] = -s*u+c*v;
-  }
-}
-
-
-/* Add a rotation around the xy-plane to the matrix m. */
-static void rotatexy(float m[4][4], float phi)
-{
-  float c, s, u, v;
-  int i;
-
-  phi *= M_PI/180.0;
-  c = cos(phi);
-  s = sin(phi);
-  for (i=0; i<4; i++)
-  {
-    u = m[i][2];
-    v = m[i][3];
-    m[i][2] = c*u+s*v;
-    m[i][3] = -s*u+c*v;
-  }
-}
-
-
-/* Add a rotation around the xz-plane to the matrix m. */
-static void rotatexz(float m[4][4], float phi)
-{
-  float c, s, u, v;
-  int i;
-
-  phi *= M_PI/180.0;
-  c = cos(phi);
-  s = sin(phi);
-  for (i=0; i<4; i++)
-  {
-    u = m[i][1];
-    v = m[i][3];
-    m[i][1] = c*u-s*v;
-    m[i][3] = s*u+c*v;
-  }
-}
-
-
-/* Add a rotation around the yz-plane to the matrix m. */
-static void rotateyz(float m[4][4], float phi)
-{
-  float c, s, u, v;
-  int i;
-
-  phi *= M_PI/180.0;
-  c = cos(phi);
-  s = sin(phi);
-  for (i=0; i<4; i++)
-  {
-    u = m[i][0];
-    v = m[i][3];
-    m[i][0] = c*u-s*v;
-    m[i][3] = s*u+c*v;
-  }
-}
-
-
-/* Compute the rotation matrix m from the rotation angles. */
-static void rotateall(float al, float be, float de, float ze, float et,
-                      float th, float m[4][4])
-{
-  int i, j;
-
-  for (i=0; i<4; i++)
-    for (j=0; j<4; j++)
-      m[i][j] = (i==j);
-  rotatewx(m,al);
-  rotatewy(m,be);
-  rotatewz(m,de);
-  rotatexz(m,et);
-  rotatexy(m,ze);
-  rotateyz(m,th);
-}
-
-
-/* Add a rotation around the x-axis to the matrix m. */
-static void rotatex(float m[3][3], float phi)
-{
-  float c, s, u, v;
-  int i;
-
-  phi *= M_PI/180.0;
-  c = cos(phi);
-  s = sin(phi);
-  for (i=0; i<3; i++)
-  {
-    u = m[i][1];
-    v = m[i][2];
-    m[i][1] = c*u+s*v;
-    m[i][2] = -s*u+c*v;
-  }
-}
-
-
-/* Add a rotation around the y-axis to the matrix m. */
-static void rotatey(float m[3][3], float phi)
-{
-  float c, s, u, v;
-  int i;
-
-  phi *= M_PI/180.0;
-  c = cos(phi);
-  s = sin(phi);
-  for (i=0; i<3; i++)
-  {
-    u = m[i][0];
-    v = m[i][2];
-    m[i][0] = c*u-s*v;
-    m[i][2] = s*u+c*v;
-  }
-}
-
-
-/* Add a rotation around the z-axis to the matrix m. */
-static void rotatez(float m[3][3], float phi)
-{
-  float c, s, u, v;
-  int i;
-
-  phi *= M_PI/180.0;
-  c = cos(phi);
-  s = sin(phi);
-  for (i=0; i<3; i++)
-  {
-    u = m[i][0];
-    v = m[i][1];
-    m[i][0] = c*u+s*v;
-    m[i][1] = -s*u+c*v;
-  }
-}
-
-
-/* Compute the 3d rotation matrix m from the 3d rotation angles. */
-static void rotateall3d(float al, float be, float de, float m[3][3])
-{
-  int i, j;
-
-  for (i=0; i<3; i++)
-    for (j=0; j<3; j++)
-      m[i][j] = (i==j);
-  rotatex(m,al);
-  rotatey(m,be);
-  rotatez(m,de);
-}
-
-
-/* Multiply two rotation matrices: o=m*n. */
-static void mult_rotmat(float m[4][4], float n[4][4], float o[4][4])
-{
-  int i, j, k;
-
-  for (i=0; i<4; i++)
-  {
-    for (j=0; j<4; j++)
-    {
-      o[i][j] = 0.0;
-      for (k=0; k<4; k++)
-        o[i][j] += m[i][k]*n[k][j];
-    }
-  }
-}
-
-
-/* Compute a 4D rotation matrix from two unit quaternions. */
-static void quats_to_rotmat(float p[4], float q[4], float m[4][4])
-{
-  double al, be, de, ze, et, th;
-  double r00, r01, r02, r12, r22;
-
-  r00 = 1.0-2.0*(p[1]*p[1]+p[2]*p[2]);
-  r01 = 2.0*(p[0]*p[1]+p[2]*p[3]);
-  r02 = 2.0*(p[2]*p[0]-p[1]*p[3]);
-  r12 = 2.0*(p[1]*p[2]+p[0]*p[3]);
-  r22 = 1.0-2.0*(p[1]*p[1]+p[0]*p[0]);
-
-  al = atan2(-r12,r22)*180.0/M_PI;
-  be = atan2(r02,sqrt(r00*r00+r01*r01))*180.0/M_PI;
-  de = atan2(-r01,r00)*180.0/M_PI;
-
-  r00 = 1.0-2.0*(q[1]*q[1]+q[2]*q[2]);
-  r01 = 2.0*(q[0]*q[1]+q[2]*q[3]);
-  r02 = 2.0*(q[2]*q[0]-q[1]*q[3]);
-  r12 = 2.0*(q[1]*q[2]+q[0]*q[3]);
-  r22 = 1.0-2.0*(q[1]*q[1]+q[0]*q[0]);
-
-  et = atan2(-r12,r22)*180.0/M_PI;
-  th = atan2(r02,sqrt(r00*r00+r01*r01))*180.0/M_PI;
-  ze = atan2(-r01,r00)*180.0/M_PI;
-
-  rotateall(al,be,de,ze,et,-th,m);
-}
-
-
-/* Compute a fully saturated and bright color based on an angle. */
-static void color(double angle, float mat[3][3], float col[4])
-{
-  int s;
-  double t, ca, sa;
-  float m;
-
-  if (!change_colors)
-  {
-    if (colors == COLORS_ONESIDED || colors == COLORS_TWOSIDED)
-      return;
-
-    if (angle >= 0.0)
-      angle = fmod(angle,2*M_PI);
-    else
-      angle = fmod(angle,-2*M_PI);
-    s = floor(angle/(M_PI/3));
-    t = angle/(M_PI/3)-s;
-    if (s >= 6)
-      s = 0;
-    switch (s)
-    {
-      case 0:
-        col[0] = 1.0;
-        col[1] = t;
-        col[2] = 0.0;
-        break;
-      case 1:
-        col[0] = 1.0-t;
-        col[1] = 1.0;
-        col[2] = 0.0;
-        break;
-      case 2:
-        col[0] = 0.0;
-        col[1] = 1.0;
-        col[2] = t;
-        break;
-      case 3:
-        col[0] = 0.0;
-        col[1] = 1.0-t;
-        col[2] = 1.0;
-        break;
-      case 4:
-        col[0] = t;
-        col[1] = 0.0;
-        col[2] = 1.0;
-        break;
-      case 5:
-        col[0] = 1.0;
-        col[1] = 0.0;
-        col[2] = 1.0-t;
-        break;
-    }
-  }
-  else /* change_colors */
-  {
-    if (colors == COLORS_ONESIDED || colors == COLORS_TWOSIDED)
-    {
-      col[0] = mat[0][2];
-      col[1] = mat[1][2];
-      col[2] = mat[2][2];
-    }
-    else
-    {
-      ca = cos(angle);
-      sa = sin(angle);
-      col[0] = ca*mat[0][0]+sa*mat[0][1];
-      col[1] = ca*mat[1][0]+sa*mat[1][1];
-      col[2] = ca*mat[2][0]+sa*mat[2][1];
-    }
-    m = 0.5f/fmaxf(fmaxf(fabsf(col[0]),fabsf(col[1])),fabsf(col[2]));
-    col[0] = m*col[0]+0.5f;
-    col[1] = m*col[1]+0.5f;
-    col[2] = m*col[2]+0.5f;
-  }
-  if (display_mode == DISP_TRANSPARENT)
-    col[3] = 0.7;
-  else
-    col[3] = 1.0;
-}
-
-
-/* Draw a hypertorus projected into 3D using OpenGL's fixed
-   functionality.  Note that the spirals appearance will only work
-   correctly if numu and numv are set to 64 or any higher power of 2.
-   Similarly, the banded appearance will only work correctly if numu
-   and numv are divisible by 4. */
-static int hypertorus_ff(ModeInfo *mi, double umin, double umax, double vmin,
-                         double vmax, int numu, int numv)
-{
-  static const GLfloat light_model_ambient[]    = { 0.2, 0.2, 0.2, 1.0 };
-  static const GLfloat light_ambient[]          = { 0.0, 0.0, 0.0, 1.0 };
-  static const GLfloat light_diffuse[]          = { 1.0, 1.0, 1.0, 1.0 };
-  static const GLfloat light_specular[]         = { 1.0, 1.0, 1.0, 1.0 };
-  static const GLfloat light_position[]         = { 1.0, 1.0, 1.0, 0.0 };
-  static const GLfloat mat_specular[]           = { 1.0, 1.0, 1.0, 1.0 };
-  static const GLfloat mat_diff_red[]           = { 1.0, 0.0, 0.0, 1.0 };
-  static const GLfloat mat_diff_green[]         = { 0.0, 1.0, 0.0, 1.0 };
-  static const GLfloat mat_diff_oneside[]       = { 0.9, 0.4, 0.3, 1.0 };
-  static const GLfloat mat_diff_trans_red[]     = { 1.0, 0.0, 0.0, 0.7 };
-  static const GLfloat mat_diff_trans_green[]   = { 0.0, 1.0, 0.0, 0.7 };
-  static const GLfloat mat_diff_trans_oneside[] = { 0.9, 0.4, 0.3, 0.7 };
-  float mat_diff_dyn[4], mat_diff_dyn_compl[4];
-  float p[3], pu[3], pv[3], n[3], mat[4][4], matc[3][3], col[4];
-  int i, j, k, l, m, b, skew;
-  double u, v, ur, vr;
-  double cu, su, cv, sv;
-  double xx[4], xxu[4], xxv[4], x[4], xu[4], xv[4];
-  double r, s, t;
-  float q1[4], q2[4], r1[4][4], r2[4][4];
-  hypertorusstruct *hp = &hyper[MI_SCREEN(mi)];
-  int polys;
-
-  glMatrixMode(GL_PROJECTION);
-  glLoadIdentity();
-  if (projection_3d == DISP_3D_ORTHOGRAPHIC)
-  {
-    if (hp->aspect >= 1.0)
-      glOrtho(-hp->aspect,hp->aspect,-1.0,1.0,0.1,10.0);
-    else
-      glOrtho(-1.0,1.0,-1.0/hp->aspect,1.0/hp->aspect,0.1,10.0);
-  }
-  else
-  {
-    gluPerspective(60.0,hp->aspect,0.1,10.0);
-  }
-  glMatrixMode(GL_MODELVIEW);
-  glLoadIdentity();
-
-  if (display_mode == DISP_SURFACE)
-  {
-    glEnable(GL_DEPTH_TEST);
-    glDepthFunc(GL_LESS);
-    glShadeModel(GL_SMOOTH);
-    glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);
-    glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,GL_TRUE);
-    glLightModelfv(GL_LIGHT_MODEL_AMBIENT,light_model_ambient);
-    glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER,GL_FALSE);
-    glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL,GL_SINGLE_COLOR);
-    glEnable(GL_LIGHTING);
-    glEnable(GL_LIGHT0);
-    glLightfv(GL_LIGHT0,GL_AMBIENT,light_ambient);
-    glLightfv(GL_LIGHT0,GL_DIFFUSE,light_diffuse);
-    glLightfv(GL_LIGHT0,GL_SPECULAR,light_specular);
-    glLightfv(GL_LIGHT0,GL_POSITION,light_position);
-    glMaterialfv(GL_FRONT_AND_BACK,GL_SPECULAR,mat_specular);
-    glMaterialf(GL_FRONT_AND_BACK,GL_SHININESS,50.0);
-    glDepthMask(GL_TRUE);
-    glDisable(GL_BLEND);
-  }
-  else if (display_mode == DISP_TRANSPARENT)
-  {
-    glDisable(GL_DEPTH_TEST);
-    glShadeModel(GL_SMOOTH);
-    glPolygonMode(GL_FRONT_AND_BACK,GL_FILL);
-    glLightModeli(GL_LIGHT_MODEL_TWO_SIDE,GL_TRUE);
-    glLightModelfv(GL_LIGHT_MODEL_AMBIENT,light_model_ambient);
-    glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER,GL_FALSE);
-    glLightModeli(GL_LIGHT_MODEL_COLOR_CONTROL,GL_SINGLE_COLOR);
-    glEnable(GL_LIGHTING);
-    glEnable(GL_LIGHT0);
-    glLightfv(GL_LIGHT0,GL_AMBIENT,light_ambient);
-    glLightfv(GL_LIGHT0,GL_DIFFUSE,light_diffuse);
-    glLightfv(GL_LIGHT0,GL_SPECULAR,light_specular);
-    glLightfv(GL_LIGHT0,GL_POSITION,light_position);
-    glMaterialfv(GL_FRONT_AND_BACK,GL_SPECULAR,mat_specular);
-    glMaterialf(GL_FRONT_AND_BACK,GL_SHININESS,50.0);
-    glDepthMask(GL_FALSE);
-    glEnable(GL_BLEND);
-    glBlendFunc(GL_SRC_ALPHA,GL_ONE);
-  }
-  else  /* display_mode == DISP_WIREFRAME */
-  {
-    glEnable(GL_DEPTH_TEST);
-    glDepthFunc(GL_LESS);
-    glShadeModel(GL_FLAT);
-    glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);
-    glDisable(GL_LIGHTING);
-    glDisable(GL_LIGHT0);
-    glDisable(GL_BLEND);
-  }
-
-  if (change_colors)
-    rotateall3d(hp->rho,hp->sigma,hp->tau,matc);
-
-  rotateall(hp->alpha,hp->beta,hp->delta,hp->zeta,hp->eta,hp->theta,r1);
-
-  gltrackball_get_quaternion(hp->trackballs[0],q1);
-  gltrackball_get_quaternion(hp->trackballs[1],q2);
-  quats_to_rotmat(q1,q2,r2);
-
-  mult_rotmat(r2,r1,mat);
-
-  if (!change_colors)
-  {
-    if (colors == COLORS_ONESIDED)
-    {
-      glColor3fv(mat_diff_oneside);
-      if (display_mode == DISP_TRANSPARENT)
-      {
-        glMaterialfv(GL_FRONT_AND_BACK,GL_AMBIENT_AND_DIFFUSE,
-                     mat_diff_trans_oneside);
-      }
-      else
-      {
-        glMaterialfv(GL_FRONT_AND_BACK,GL_AMBIENT_AND_DIFFUSE,
-                     mat_diff_oneside);
-      }
-    }
-    else if (colors == COLORS_TWOSIDED)
-    {
-      glColor3fv(mat_diff_red);
-      if (display_mode == DISP_TRANSPARENT)
-      {
-        glMaterialfv(GL_FRONT,GL_AMBIENT_AND_DIFFUSE,mat_diff_trans_red);
-        glMaterialfv(GL_BACK,GL_AMBIENT_AND_DIFFUSE,mat_diff_trans_green);
-      }
-      else
-      {
-        glMaterialfv(GL_FRONT,GL_AMBIENT_AND_DIFFUSE,mat_diff_red);
-        glMaterialfv(GL_BACK,GL_AMBIENT_AND_DIFFUSE,mat_diff_green);
-      }
-    }
-  }
-  else /* change_colors */
-  {
-    color(0.0,matc,mat_diff_dyn);
-    if (colors == COLORS_ONESIDED)
-    {
-      glColor3fv(mat_diff_dyn);
-      glMaterialfv(GL_FRONT_AND_BACK,GL_AMBIENT_AND_DIFFUSE,mat_diff_dyn);
-    }
-    else if (colors == COLORS_TWOSIDED)
-    {
-      mat_diff_dyn_compl[0] = 1.0f-mat_diff_dyn[0];
-      mat_diff_dyn_compl[1] = 1.0f-mat_diff_dyn[1];
-      mat_diff_dyn_compl[2] = 1.0f-mat_diff_dyn[2];
-      mat_diff_dyn_compl[3] = mat_diff_dyn[3];
-      glColor3fv(mat_diff_dyn);
-      glMaterialfv(GL_FRONT,GL_AMBIENT_AND_DIFFUSE,mat_diff_dyn);
-      glMaterialfv(GL_BACK,GL_AMBIENT_AND_DIFFUSE,mat_diff_dyn_compl);
-    }
-  }
-
-  skew = num_spirals;
-  ur = umax-umin;
-  vr = vmax-vmin;
-  for (i=0; i<numu; i++)
-  {
-    if ((appearance == APPEARANCE_BANDS ||
-         appearance == APPEARANCE_SPIRALS) && ((i & 3) >= 2))
-      continue;
-    if (display_mode == DISP_WIREFRAME)
-      glBegin(GL_QUAD_STRIP);
-    else
-      glBegin(GL_TRIANGLE_STRIP);
-    for (j=0; j<=numv; j++)
-    {
-      for (k=0; k<=1; k++)
-      {
-        l = i+k;
-        m = j;
-        u = ur*l/numu+umin;
-        v = vr*m/numv+vmin;
-        if (appearance == APPEARANCE_SPIRALS)
-        {
-          u += 4.0*skew/numv*v;
-          b = ((i/4)&(skew-1))*(numu/(4*skew));
-          color(ur*4*b/numu+umin,matc,col);
-        }
-        else
-        {
-          color(u,matc,col);
-        }
-        if (colors == COLORS_COLORWHEEL)
-        {
-          glColor3fv(col);
-          glMaterialfv(GL_FRONT_AND_BACK,GL_AMBIENT_AND_DIFFUSE,col);
-        }
-        cu = cos(u);
-        su = sin(u);
-        cv = cos(v);
-        sv = sin(v);
-        xx[0] = cu;
-        xx[1] = su;
-        xx[2] = cv;
-        xx[3] = sv;
-        xxu[0] = -su;
-        xxu[1] = cu;
-        xxu[2] = 0.0;
-        xxu[3] = 0.0;
-        xxv[0] = 0.0;
-        xxv[1] = 0.0;
-        xxv[2] = -sv;
-        xxv[3] = cv;
-        for (l=0; l<4; l++)
-        {
-          r = 0.0;
-          s = 0.0;
-          t = 0.0;
-          for (m=0; m<4; m++)
-          {
-            r += mat[l][m]*xx[m];
-            s += mat[l][m]*xxu[m];
-            t += mat[l][m]*xxv[m];
-          }
-          x[l] = r;
-          xu[l] = s;
-          xv[l] = t;
-        }
-        if (projection_4d == DISP_4D_ORTHOGRAPHIC)
-        {
-          for (l=0; l<3; l++)
-          {
-            p[l] = (x[l]+offset4d[l])/1.5+offset3d[l];
-            pu[l] = xu[l];
-            pv[l] = xv[l];
-          }
-        }
-        else
-        {
-          s = x[3]+offset4d[3];
-          t = s*s;
-          for (l=0; l<3; l++)
-          {
-            r = x[l]+offset4d[l];
-            p[l] = r/s+offset3d[l];
-            pu[l] = (xu[l]*s-r*xu[3])/t;
-            pv[l] = (xv[l]*s-r*xv[3])/t;
-          }
-        }
-        n[0] = pu[1]*pv[2]-pu[2]*pv[1];
-        n[1] = pu[2]*pv[0]-pu[0]*pv[2];
-        n[2] = pu[0]*pv[1]-pu[1]*pv[0];
-        t = sqrt(n[0]*n[0]+n[1]*n[1]+n[2]*n[2]);
-        n[0] /= t;
-        n[1] /= t;
-        n[2] /= t;
-        glNormal3fv(n);
-        glVertex3fv(p);
-      }
-    }
-    glEnd();
-  }
-
-  polys = 2*numu*numv;
-  if (appearance != APPEARANCE_SOLID)
-    polys /= 2;
-  return polys;
-}
-
-
-#ifdef HAVE_GLSL
-
-/* Draw a hypertorus projected into 3D using OpenGL's programmable
-   functionality.  Note that the spirals appearance will only work
-   correctly if numu and numv are set to 64 or any higher power of 2.
-   Similarly, the banded appearance will only work correctly if numu
-   and numv are divisible by 4. */
-static int hypertorus_pf(ModeInfo *mi, double umin, double umax, double vmin,
-                         double vmax, int numu, int numv)
-{
-  static const GLfloat light_model_ambient[]    = { 0.2, 0.2, 0.2, 1.0 };
-  static const GLfloat light_ambient[]          = { 0.0, 0.0, 0.0, 1.0 };
-  static const GLfloat light_diffuse[]          = { 1.0, 1.0, 1.0, 1.0 };
-  static const GLfloat light_specular[]         = { 1.0, 1.0, 1.0, 1.0 };
-  static const GLfloat light_position[]         = { 1.0, 1.0, 1.0, 0.0 };
-  static const GLfloat mat_specular[]           = { 1.0, 1.0, 1.0, 1.0 };
-  static const GLfloat mat_diff_red[]           = { 1.0, 0.0, 0.0, 1.0 };
-  static const GLfloat mat_diff_green[]         = { 0.0, 1.0, 0.0, 1.0 };
-  static const GLfloat mat_diff_oneside[]       = { 0.9, 0.4, 0.3, 1.0 };
-  static const GLfloat mat_diff_trans_red[]     = { 1.0, 0.0, 0.0, 0.7 };
-  static const GLfloat mat_diff_trans_green[]   = { 0.0, 1.0, 0.0, 0.7 };
-  static const GLfloat mat_diff_trans_oneside[] = { 0.9, 0.4, 0.3, 0.7 };
-  static const GLfloat mat_diff_white[]         = { 1.0, 1.0, 1.0, 1.0 };
-  GLfloat light_direction[3], half_vector[3], len;
-  GLfloat p_mat[16];
-  float mat_diff_dyn[4], mat_diff_dyn_compl[4];
-  float mat[4][4], matc[3][3];
-  int i, j, k, l, m, o, b, skew;
-  double u, v, ur, vr;
-  float q1[4], q2[4], r1[4][4], r2[4][4];
-  GLsizeiptr index_offset;
-  hypertorusstruct *hp = &hyper[MI_SCREEN(mi)];
-  int polys;
-
-  if (!hp->use_shaders)
-    return 0;
-
-  if (change_colors)
-    rotateall3d(hp->rho,hp->sigma,hp->tau,matc);
-
-  rotateall(hp->alpha,hp->beta,hp->delta,hp->zeta,hp->eta,hp->theta,r1);
-
-  gltrackball_get_quaternion(hp->trackballs[0],q1);
-  gltrackball_get_quaternion(hp->trackballs[1],q2);
-  quats_to_rotmat(q1,q2,r2);
-
-  mult_rotmat(r2,r1,mat);
-
-  if (!hp->buffers_initialized)
-  {
-    /* The u and v values need to be computed once (or each time the value
-       of appearance changes, once we support that). */
-    skew = num_spirals;
-    ur = umax-umin;
-    vr = vmax-vmin;
-    for (i=0; i<=numu; i++)
-    {
-      for (j=0; j<=numv; j++)
-      {
-        u = ur*i/numu+umin;
-        v = vr*j/numv+vmin;
-        o = i*(numv+1)+j;
-        if (appearance == APPEARANCE_SPIRALS)
-          u += 4.0*skew/numv*v;
-        hp->uv[o][0] = u;
-        hp->uv[o][1] = v;
-      }
-    }
-    glBindBuffer(GL_ARRAY_BUFFER,hp->vertex_uv_buffer);
-    glBufferData(GL_ARRAY_BUFFER,2*(NUMU+1)*(NUMV+1)*sizeof(GLfloat),
-                 hp->uv,GL_STATIC_DRAW);
-    glBindBuffer(GL_ARRAY_BUFFER,0);
-
-    if (!change_colors && colors == COLORS_COLORWHEEL)
-    {
-      for (i=0; i<=numu; i++)
-      {
-        for (j=0; j<=numv; j++)
-        {
-          u = ur*i/numu+umin;
-          v = vr*j/numv+vmin;
-          o = i*(numv+1)+j;
-          if (appearance == APPEARANCE_SPIRALS)
-          {
-            u += 4.0*skew/numv*v;
-            b = ((i/4)&(skew-1))*(numu/(4*skew));
-            color(ur*4*b/numu+umin,matc,&hp->col[o][0]);
-          }
-          else
-          {
-            color(u,matc,&hp->col[o][0]);
-          }
-        }
-      }
-      glBindBuffer(GL_ARRAY_BUFFER,hp->color_buffer);
-      glBufferData(GL_ARRAY_BUFFER,4*(NUMU+1)*(NUMV+1)*sizeof(GLfloat),
-                   hp->col,GL_STATIC_DRAW);
-      glBindBuffer(GL_ARRAY_BUFFER,0);
-    }
-#ifdef VERTEXATTRIBARRAY_WORKAROUND
-    if (colors != COLORS_COLORWHEEL)
-    {
-      for (i=0; i<=numu; i++)
-      {
-        for (j=0; j<=numv; j++)
-        {
-          o = i*(numv+1)+j;
-          if (display_mode == DISP_WIREFRAME)
-          {
-            if (colors == COLORS_ONESIDED)
-            {
-              for (k=0; k<4; k++)
-                hp->col[o][k] = mat_diff_oneside[k];
-            }
-            else if (colors == COLORS_TWOSIDED)
-            {
-              for (k=0; k<4; k++)
-                hp->col[o][k] = mat_diff_red[k];
-            }
-          }
-          else
-          {
-            for (k=0; k<4; k++)
-              hp->col[o][k] = mat_diff_white[k];
-          }
-        }
-      }
-      glBindBuffer(GL_ARRAY_BUFFER,hp->color_buffer);
-      glBufferData(GL_ARRAY_BUFFER,4*(NUMU+1)*(NUMV+1)*sizeof(GLfloat),
-                   hp->col,GL_STATIC_DRAW);
-      glBindBuffer(GL_ARRAY_BUFFER,0);
-    }
-#endif /* VERTEXATTRIBARRAY_WORKAROUND */
-
-    /* The indices only need to be computed once (or each time the value
-       of appearance changes, once we support that). */
-    hp->ne = 0;
-    hp->ni = 0;
-    hp->nt = 0;
-    if (display_mode != DISP_WIREFRAME)
-    {
-      for (i=0; i<numu; i++)
-      {
-        if ((appearance == APPEARANCE_BANDS ||
-             appearance == APPEARANCE_SPIRALS) && ((i & 3) >= 2))
-          continue;
-        for (j=0; j<=numv; j++)
-        {
-          for (k=0; k<=1; k++)
-          {
-            l = i+k;
-            m = j;
-            o = l*(numv+1)+m;
-            hp->indices[hp->ni++] = o;
-          }
-        }
-        hp->ne++;
-      }
-      hp->nt = 2*(numv+1);
-    }
-    else /* display_mode == DISP_WIREFRAME */
-    {
-      for (i=0; i<numu; i++)
-      {
-        if ((appearance == APPEARANCE_BANDS ||
-             appearance == APPEARANCE_SPIRALS) && ((i & 3) > 2))
-          continue;
-        if ((appearance == APPEARANCE_BANDS ||
-             appearance == APPEARANCE_SPIRALS) && ((i & 3) == 2))
-        {
-          for (j=0; j<numv; j++)
-          {
-            hp->indices[hp->ni++] = i*(numv+1)+j;
-            hp->indices[hp->ni++] = i*(numv+1)+j+1;
-          }
-          continue;
-        }
-        for (j=0; j<numv; j++)
-        {
-          hp->indices[hp->ni++] = i*(numv+1)+j;
-          hp->indices[hp->ni++] = i*(numv+1)+j+1;
-          hp->indices[hp->ni++] = i*(numv+1)+j;
-          hp->indices[hp->ni++] = (i+1)*(numv+1)+j;
-        }
-      }
-      hp->ne = 1;
-    }
-    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,hp->indices_buffer);
-    glBufferData(GL_ELEMENT_ARRAY_BUFFER,hp->ni*sizeof(GLuint),
-                 hp->indices,GL_STATIC_DRAW);
-    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,0);
-    hp->buffers_initialized = True;
-  }
-
-  if (change_colors && colors == COLORS_COLORWHEEL)
-  {
-    skew = num_spirals;
-    ur = umax-umin;
-    vr = vmax-vmin;
-    for (i=0; i<=numu; i++)
-    {
-      for (j=0; j<=numv; j++)
-      {
-        u = ur*i/numu+umin;
-        v = vr*j/numv+vmin;
-        o = i*(numv+1)+j;
-        if (appearance == APPEARANCE_SPIRALS)
-        {
-          u += 4.0*skew/numv*v;
-          b = ((i/4)&(skew-1))*(numu/(4*skew));
-          color(ur*4*b/numu+umin,matc,&hp->col[o][0]);
-        }
-        else
-        {
-          color(u,matc,&hp->col[o][0]);
-        }
-      }
-    }
-  }
-#ifdef VERTEXATTRIBARRAY_WORKAROUND
-  else if (change_colors && colors != COLORS_COLORWHEEL)
-  {
-    if (display_mode == DISP_WIREFRAME)
-    {
-      color(0.0,matc,mat_diff_dyn);
-      for (i=0; i<=numu; i++)
-      {
-        for (j=0; j<=numv; j++)
-        {
-          o = i*(numv+1)+j;
-          for (k=0; k<4; k++)
-            hp->col[o][k] = mat_diff_dyn[k];
-        }
-      }
-    }
-  }
-#endif /* VERTEXATTRIBARRAY_WORKAROUND */
-
-  glUseProgram(hp->shader_program);
-
-  glsl_Identity(p_mat);
-  if (projection_3d == DISP_3D_ORTHOGRAPHIC)
-  {
-    if (hp->aspect >= 1.0)
-      glsl_Orthographic(p_mat,-hp->aspect,hp->aspect,-1.0,1.0,
-                        0.1,10.0);
-    else
-      glsl_Orthographic(p_mat,-1.0,1.0,-1.0/hp->aspect,1.0/hp->aspect,
-                        0.1,10.0);
-  }
-  else
-  {
-    glsl_Perspective(p_mat,60.0f,hp->aspect,0.1f,10.0f);
-  }
-  glUniformMatrix4fv(hp->mat_rot_index,1,GL_TRUE,(GLfloat *)mat);
-  glUniformMatrix4fv(hp->mat_p_index,1,GL_FALSE,p_mat);
-  glUniform1i(hp->bool_persp_index,projection_4d == DISP_4D_PERSPECTIVE);
-  glUniform4fv(hp->off4d_index,1,offset4d);
-  glUniform4fv(hp->off3d_index,1,offset3d);
-
-  len = sqrtf(light_position[0]*light_position[0]+
-              light_position[1]*light_position[1]+
-              light_position[2]*light_position[2]);
-  light_direction[0] = light_position[0]/len;
-  light_direction[1] = light_position[1]/len;
-  light_direction[2] = light_position[2]/len;
-  half_vector[0] = light_direction[0];
-  half_vector[1] = light_direction[1];
-  half_vector[2] = light_direction[2]+1.0f;
-  len = sqrtf(half_vector[0]*half_vector[0]+
-              half_vector[1]*half_vector[1]+
-              half_vector[2]*half_vector[2]);
-  half_vector[0] /= len;
-  half_vector[1] /= len;
-  half_vector[2] /= len;
-
-  if (display_mode == DISP_SURFACE)
-  {
-    glEnable(GL_DEPTH_TEST);
-    glDepthFunc(GL_LESS);
-    glDepthMask(GL_TRUE);
-    glDisable(GL_BLEND);
-    glUniform4fv(hp->glbl_ambient_index,1,light_model_ambient);
-    glUniform4fv(hp->lt_ambient_index,1,light_ambient);
-    glUniform4fv(hp->lt_diffuse_index,1,light_diffuse);
-    glUniform4fv(hp->lt_specular_index,1,light_specular);
-    glUniform3fv(hp->lt_direction_index,1,light_direction);
-    glUniform3fv(hp->lt_halfvect_index,1,half_vector);
-    glUniform4fv(hp->specular_index,1,mat_specular);
-    glUniform1f(hp->shininess_index,50.0f);
-    glUniform1i(hp->draw_lines_index,GL_FALSE);
-  }
-  else if (display_mode == DISP_TRANSPARENT)
-  {
-    glDisable(GL_DEPTH_TEST);
-    glDepthMask(GL_FALSE);
-    glEnable(GL_BLEND);
-    glBlendFunc(GL_SRC_ALPHA,GL_ONE);
-    glUniform4fv(hp->glbl_ambient_index,1,light_model_ambient);
-    glUniform4fv(hp->lt_ambient_index,1,light_ambient);
-    glUniform4fv(hp->lt_diffuse_index,1,light_diffuse);
-    glUniform4fv(hp->lt_specular_index,1,light_specular);
-    glUniform3fv(hp->lt_direction_index,1,light_direction);
-    glUniform3fv(hp->lt_halfvect_index,1,half_vector);
-    glUniform4fv(hp->specular_index,1,mat_specular);
-    glUniform1f(hp->shininess_index,50.0f);
-    glUniform1i(hp->draw_lines_index,GL_FALSE);
-  }
-  else /* display_mode == DISP_WIREFRAME */
-  {
-    glEnable(GL_DEPTH_TEST);
-    glDepthFunc(GL_LESS);
-    glDepthMask(GL_TRUE);
-    glDisable(GL_BLEND);
-    glUniform1i(hp->draw_lines_index,GL_TRUE);
-  }
-
-  glUniform4fv(hp->front_ambient_index,1,mat_diff_white);
-  glUniform4fv(hp->front_diffuse_index,1,mat_diff_white);
-  glUniform4fv(hp->back_ambient_index,1,mat_diff_white);
-  glUniform4fv(hp->back_diffuse_index,1,mat_diff_white);
-  glVertexAttrib4f(hp->color_index,1.0f,1.0f,1.0f,1.0f);
-  if (!change_colors)
-  {
-    if (colors == COLORS_ONESIDED)
-    {
-      if (display_mode == DISP_TRANSPARENT)
-      {
-        glUniform4fv(hp->front_ambient_index,1,mat_diff_trans_oneside);
-        glUniform4fv(hp->front_diffuse_index,1,mat_diff_trans_oneside);
-        glUniform4fv(hp->back_ambient_index,1,mat_diff_trans_oneside);
-        glUniform4fv(hp->back_diffuse_index,1,mat_diff_trans_oneside);
-      }
-      else if (display_mode == DISP_SURFACE)
-      {
-        glUniform4fv(hp->front_ambient_index,1,mat_diff_oneside);
-        glUniform4fv(hp->front_diffuse_index,1,mat_diff_oneside);
-        glUniform4fv(hp->back_ambient_index,1,mat_diff_oneside);
-        glUniform4fv(hp->back_diffuse_index,1,mat_diff_oneside);
-      }
-      else /* display_mode == DISP_WIREFRAME */
-      {
-        glVertexAttrib4fv(hp->color_index,mat_diff_oneside);
-      }
-    }
-    else if (colors == COLORS_TWOSIDED)
-    {
-      if (display_mode == DISP_TRANSPARENT)
-      {
-        glUniform4fv(hp->front_ambient_index,1,mat_diff_trans_red);
-        glUniform4fv(hp->front_diffuse_index,1,mat_diff_trans_red);
-        glUniform4fv(hp->back_ambient_index,1,mat_diff_trans_green);
-        glUniform4fv(hp->back_diffuse_index,1,mat_diff_trans_green);
-      }
-      else if (display_mode == DISP_SURFACE)
-      {
-        glUniform4fv(hp->front_ambient_index,1,mat_diff_red);
-        glUniform4fv(hp->front_diffuse_index,1,mat_diff_red);
-        glUniform4fv(hp->back_ambient_index,1,mat_diff_green);
-        glUniform4fv(hp->back_diffuse_index,1,mat_diff_green);
-      }
-      else /* display_mode == DISP_WIREFRAME */
-      {
-        glVertexAttrib4fv(hp->color_index,mat_diff_red);
-      }
-    }
-  }
-  else /* change_colors */
-  {
-    color(0.0,matc,mat_diff_dyn);
-    if (colors == COLORS_ONESIDED)
-    {
-      if (display_mode == DISP_TRANSPARENT || display_mode == DISP_SURFACE)
-      {
-        glUniform4fv(hp->front_ambient_index,1,mat_diff_dyn);
-        glUniform4fv(hp->front_diffuse_index,1,mat_diff_dyn);
-        glUniform4fv(hp->back_ambient_index,1,mat_diff_dyn);
-        glUniform4fv(hp->back_diffuse_index,1,mat_diff_dyn);
-      }
-      else /* display_mode == DISP_WIREFRAME */
-      {
-        glVertexAttrib4fv(hp->color_index,mat_diff_dyn);
-      }
-    }
-    else if (colors == COLORS_TWOSIDED)
-    {
-      if (display_mode == DISP_TRANSPARENT || display_mode == DISP_SURFACE)
-      {
-        mat_diff_dyn_compl[0] = 1.0f-mat_diff_dyn[0];
-        mat_diff_dyn_compl[1] = 1.0f-mat_diff_dyn[1];
-        mat_diff_dyn_compl[2] = 1.0f-mat_diff_dyn[2];
-        mat_diff_dyn_compl[3] = mat_diff_dyn[3];
-        glUniform4fv(hp->front_ambient_index,1,mat_diff_dyn);
-        glUniform4fv(hp->front_diffuse_index,1,mat_diff_dyn);
-        glUniform4fv(hp->back_ambient_index,1,mat_diff_dyn_compl);
-        glUniform4fv(hp->back_diffuse_index,1,mat_diff_dyn_compl);
-      }
-      else /* display_mode == DISP_WIREFRAME */
-      {
-        glVertexAttrib4fv(hp->color_index,mat_diff_dyn);
-      }
-    }
-  }
-
-  glEnableVertexAttribArray(hp->vertex_uv_index);
-  glBindBuffer(GL_ARRAY_BUFFER,hp->vertex_uv_buffer);
-  glVertexAttribPointer(hp->vertex_uv_index,2,GL_FLOAT,GL_FALSE,0,0);
-
-  if (colors == COLORS_COLORWHEEL)
-  {
-    glEnableVertexAttribArray(hp->color_index);
-    glBindBuffer(GL_ARRAY_BUFFER,hp->color_buffer);
-    if (change_colors)
-      glBufferData(GL_ARRAY_BUFFER,4*(NUMU+1)*(NUMV+1)*sizeof(GLfloat),
-                   hp->col,GL_STREAM_DRAW);
-    glVertexAttribPointer(hp->color_index,4,GL_FLOAT,GL_FALSE,0,0);
-  }
-#ifdef VERTEXATTRIBARRAY_WORKAROUND
-  else
-  {
-    glEnableVertexAttribArray(hp->color_index);
-    glBindBuffer(GL_ARRAY_BUFFER,hp->color_buffer);
-    if (change_colors)
-      glBufferData(GL_ARRAY_BUFFER,4*(NUMU+1)*(NUMV+1)*sizeof(GLfloat),
-                   hp->col,GL_STREAM_DRAW);
-    glVertexAttribPointer(hp->color_index,4,GL_FLOAT,GL_FALSE,0,0);
-  }
-#endif /* VERTEXATTRIBARRAY_WORKAROUND */
-
-  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,hp->indices_buffer);
-
-  if (display_mode != DISP_WIREFRAME)
-  {
-    for (i=0; i<hp->ne; i++)
-    {
-      index_offset = hp->nt*i*sizeof(GLuint);
-      glDrawElements(GL_TRIANGLE_STRIP,hp->nt,GL_UNSIGNED_INT,
-                     (const void *)index_offset);
-    }
-  }
-  else /* display_mode == DISP_WIREFRAME */
-  {
-    glLineWidth(1.0f);
-    index_offset = 0;
-    glDrawElements(GL_LINES,hp->ni,GL_UNSIGNED_INT,
-                   (const void *)index_offset);
-  }
-
-  glDisableVertexAttribArray(hp->vertex_uv_index);
-  if (colors == COLORS_COLORWHEEL)
-    glDisableVertexAttribArray(hp->color_index);
-#ifdef VERTEXATTRIBARRAY_WORKAROUND
-  else
-    glDisableVertexAttribArray(hp->color_index);
-#endif /* VERTEXATTRIBARRAY_WORKAROUND */
-  glBindBuffer(GL_ARRAY_BUFFER,0);
-  glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,0);
-
-  glUseProgram(0);
-
-  polys = 2*numu*numv;
-  if (appearance != APPEARANCE_SOLID)
-    polys /= 2;
-  return polys;
-}
-
-
-static void init_glsl(ModeInfo *mi)
-{
-  hypertorusstruct *hp = &hyper[MI_SCREEN(mi)];
-  GLint gl_major, gl_minor, glsl_major, glsl_minor;
-  GLboolean gl_gles3;
-  const GLchar *vertex_shader_source[3];
-  const GLchar *fragment_shader_source[4];
-
-  /* Determine whether to use shaders to render the hypertorus. */
-  hp->use_shaders = False;
-  hp->buffers_initialized = False;
-  hp->shader_program = 0;
-  hp->ni = 0;
-  hp->ne = 0;
-  hp->nt = 0;
-
-  if (!glsl_GetGlAndGlslVersions(&gl_major,&gl_minor,&glsl_major,&glsl_minor,
-                                 &gl_gles3))
-    return;
-  if (!gl_gles3)
-  {
-    if (gl_major < 3 ||
-        (glsl_major < 1 || (glsl_major == 1 && glsl_minor < 30)))
-    {
-      if ((gl_major < 2 || (gl_major == 2 && gl_minor < 1)) ||
-          (glsl_major < 1 || (glsl_major == 1 && glsl_minor < 20)))
-        return;
-      /* We have at least OpenGL 2.1 and at least GLSL 1.20. */
-      vertex_shader_source[0] = shader_version_2_1;
-      vertex_shader_source[1] = vertex_shader_attribs_2_1;
-      vertex_shader_source[2] = vertex_shader_main;
-      fragment_shader_source[0] = shader_version_2_1;
-      fragment_shader_source[1] = fragment_shader_attribs_2_1;
-      fragment_shader_source[2] = fragment_shader_main;
-      fragment_shader_source[3] = fragment_shader_out_2_1;
-    }
-    else
-    {
-      /* We have at least OpenGL 3.0 and at least GLSL 1.30. */
-      vertex_shader_source[0] = shader_version_3_0;
-      vertex_shader_source[1] = vertex_shader_attribs_3_0;
-      vertex_shader_source[2] = vertex_shader_main;
-      fragment_shader_source[0] = shader_version_3_0;
-      fragment_shader_source[1] = fragment_shader_attribs_3_0;
-      fragment_shader_source[2] = fragment_shader_main;
-      fragment_shader_source[3] = fragment_shader_out_3_0;
-    }
-  }
-  else /* gl_gles3 */
-  {
-    if (gl_major < 3 || glsl_major < 3)
-      return;
-    /* We have at least OpenGL ES 3.0 and at least GLSL ES 3.0. */
-    vertex_shader_source[0] = shader_version_3_0_es;
-    vertex_shader_source[1] = vertex_shader_attribs_3_0;
-    vertex_shader_source[2] = vertex_shader_main;
-    fragment_shader_source[0] = shader_version_3_0_es;
-    fragment_shader_source[1] = fragment_shader_attribs_3_0;
-    fragment_shader_source[2] = fragment_shader_main;
-    fragment_shader_source[3] = fragment_shader_out_3_0;
-  }
-  if (!glsl_CompileAndLinkShaders(3,vertex_shader_source,
-                                  4,fragment_shader_source,
-                                  &hp->shader_program))
-    return;
-  hp->vertex_uv_index = glGetAttribLocation(hp->shader_program,"VertexUV");
-  hp->color_index = glGetAttribLocation(hp->shader_program,"VertexColor");
-  if (hp->vertex_uv_index == -1 || hp->color_index == -1)
-  {
-    glDeleteProgram(hp->shader_program);
-    return;
-  }
-  hp->mat_rot_index = glGetUniformLocation(hp->shader_program,
-                                           "MatRot4D");
-  hp->mat_p_index = glGetUniformLocation(hp->shader_program,
-                                         "MatProj");
-  hp->bool_persp_index = glGetUniformLocation(hp->shader_program,
-                                              "BoolPersp");
-  hp->off4d_index = glGetUniformLocation(hp->shader_program,
-                                         "Offset4D");
-  hp->off3d_index = glGetUniformLocation(hp->shader_program,
-                                         "Offset3D");
-  hp->draw_lines_index = glGetUniformLocation(hp->shader_program,
-                                              "DrawLines");
-  hp->glbl_ambient_index = glGetUniformLocation(hp->shader_program,
-                                                "LtGlblAmbient");
-  hp->lt_ambient_index = glGetUniformLocation(hp->shader_program,
-                                              "LtAmbient");
-  hp->lt_diffuse_index = glGetUniformLocation(hp->shader_program,
-                                              "LtDiffuse");
-  hp->lt_specular_index = glGetUniformLocation(hp->shader_program,
-                                               "LtSpecular");
-  hp->lt_direction_index = glGetUniformLocation(hp->shader_program,
-                                                "LtDirection");
-  hp->lt_halfvect_index = glGetUniformLocation(hp->shader_program,
-                                               "LtHalfVector");
-  hp->front_ambient_index = glGetUniformLocation(hp->shader_program,
-                                                 "MatFrontAmbient");
-  hp->back_ambient_index = glGetUniformLocation(hp->shader_program,
-                                                "MatBackAmbient");
-  hp->front_diffuse_index = glGetUniformLocation(hp->shader_program,
-                                                 "MatFrontDiffuse");
-  hp->back_diffuse_index = glGetUniformLocation(hp->shader_program,
-                                                "MatBackDiffuse");
-  hp->specular_index = glGetUniformLocation(hp->shader_program,
-                                            "MatSpecular");
-  hp->shininess_index = glGetUniformLocation(hp->shader_program,
-                                             "MatShininess");
-  if (hp->mat_rot_index == -1 || hp->mat_p_index == -1 ||
-      hp->bool_persp_index == -1 || hp->off4d_index  == -1 ||
-      hp->off3d_index  == -1 || hp->draw_lines_index == -1 ||
-      hp->glbl_ambient_index == -1 || hp->lt_ambient_index == -1 ||
-      hp->lt_diffuse_index == -1 || hp->lt_specular_index == -1 ||
-      hp->lt_direction_index == -1 || hp->lt_halfvect_index == -1 ||
-      hp->specular_index == -1 || hp->shininess_index == -1 ||
-      hp->front_ambient_index == -1 || hp->back_ambient_index == -1 ||
-      hp->front_diffuse_index == -1 || hp->back_diffuse_index == -1)
-  {
-    glDeleteProgram(hp->shader_program);
-    return;
-  }
-
-  glGenBuffers(1,&hp->vertex_uv_buffer);
-  glGenBuffers(1,&hp->color_buffer);
-  glGenBuffers(1,&hp->indices_buffer);
-
-  hp->use_shaders = True;
-}
-
-#endif /* HAVE_GLSL */
-
-
-static void init(ModeInfo *mi)
-{
-  hypertorusstruct *hp = &hyper[MI_SCREEN(mi)];
-
-  hp->alpha = 0.0;
-  hp->beta = 0.0;
-  hp->delta = 0.0;
-  hp->zeta = 0.0;
-  hp->eta = 0.0;
-  hp->theta = 0.0;
-
-  hp->rho = frand(360.0);
-  hp->sigma = frand(360.0);
-  hp->tau = frand(360.0);
-
-#ifdef HAVE_GLSL
-  init_glsl(mi);
-#endif /* HAVE_GLSL */
-
-#ifdef HAVE_ANDROID
-  /* glPolygonMode(...,GL_LINE) is not supported for an OpenGL ES 1.1
-     context. */
-  if (!hp->use_shaders && display_mode == DISP_WIREFRAME)
-    display_mode = DISP_SURFACE;
-#endif /* HAVE_ANDROID */
-}
-
-
-/* Redisplay the hypertorus. */
-static void display_hypertorus(ModeInfo *mi)
-{
-  hypertorusstruct *hp = &hyper[MI_SCREEN(mi)];
-
-  if (!hp->button_pressed)
-  {
-    hp->alpha += speed_wx * hp->speed_scale;
-    if (hp->alpha >= 360.0)
-      hp->alpha -= 360.0;
-    hp->beta += speed_wy * hp->speed_scale;
-    if (hp->beta >= 360.0)
-      hp->beta -= 360.0;
-    hp->delta += speed_wz * hp->speed_scale;
-    if (hp->delta >= 360.0)
-      hp->delta -= 360.0;
-    hp->zeta += speed_xy * hp->speed_scale;
-    if (hp->zeta >= 360.0)
-      hp->zeta -= 360.0;
-    hp->eta += speed_xz * hp->speed_scale;
-    if (hp->eta >= 360.0)
-      hp->eta -= 360.0;
-    hp->theta += speed_yz * hp->speed_scale;
-    if (hp->theta >= 360.0)
-      hp->theta -= 360.0;
-
-    if (change_colors)
-    {
-      hp->rho += DRHO;
-      if (hp->rho >= 360.0)
-        hp->rho -= 360.0;
-      hp->sigma += DSIGMA;
-      if (hp->sigma >= 360.0)
-        hp->sigma -= 360.0;
-      hp->tau += DTAU;
-      if (hp->tau >= 360.0)
-        hp->tau -= 360.0;
-    }
-  }
-
-#ifdef HAVE_GLSL
-  if (hp->use_shaders)
-    mi->polygon_count = hypertorus_pf(mi,0.0,2.0*M_PI,0.0,2.0*M_PI,NUMU,NUMV);
-  else
-#endif /* HAVE_GLSL */
-    mi->polygon_count = hypertorus_ff(mi,0.0,2.0*M_PI,0.0,2.0*M_PI,NUMU,NUMV);
-}
-
-
-ENTRYPOINT void reshape_hypertorus(ModeInfo *mi, int width, int height)
-{
-  hypertorusstruct *hp = &hyper[MI_SCREEN(mi)];
-
-  hp->WindW = (GLint)width;
-  hp->WindH = (GLint)height;
-  glViewport(0,0,width,height);
-  hp->aspect = (GLfloat)width/(GLfloat)height;
-}
-
-
-ENTRYPOINT Bool hypertorus_handle_event(ModeInfo *mi, XEvent *event)
-{
-  hypertorusstruct *hp = &hyper[MI_SCREEN(mi)];
-  KeySym  sym = 0;
-  char c = 0;
-
-  if (event->xany.type == KeyPress || event->xany.type == KeyRelease)
-    XLookupString (&event->xkey, &c, 1, &sym, 0);
-
-  if (event->xany.type == ButtonPress &&
-      event->xbutton.button == Button1)
-  {
-    hp->button_pressed = True;
-    gltrackball_start(hp->trackballs[hp->current_trackball],
-                      event->xbutton.x, event->xbutton.y,
-                      MI_WIDTH(mi), MI_HEIGHT(mi));
-    return True;
-  }
-  else if (event->xany.type == ButtonRelease &&
-           event->xbutton.button == Button1)
-  {
-    hp->button_pressed = False;
-    return True;
-  }
-  else if (event->xany.type == KeyPress)
-  {
-    if (sym == XK_Shift_L || sym == XK_Shift_R)
-    {
-      hp->current_trackball = 1;
-      if (hp->button_pressed)
-        gltrackball_start(hp->trackballs[hp->current_trackball],
-                          event->xbutton.x, event->xbutton.y,
-                          MI_WIDTH(mi), MI_HEIGHT(mi));
-      return True;
-    }
-  }
-  else if (event->xany.type == KeyRelease)
-  {
-    if (sym == XK_Shift_L || sym == XK_Shift_R)
-    {
-      hp->current_trackball = 0;
-      if (hp->button_pressed)
-        gltrackball_start(hp->trackballs[hp->current_trackball],
-                          event->xbutton.x, event->xbutton.y,
-                          MI_WIDTH(mi), MI_HEIGHT(mi));
-      return True;
-    }
-  }
-  else if (event->xany.type == MotionNotify && hp->button_pressed)
-  {
-    gltrackball_track(hp->trackballs[hp->current_trackball],
-                      event->xmotion.x, event->xmotion.y,
-                      MI_WIDTH(mi), MI_HEIGHT(mi));
-    return True;
-  }
-
-  return False;
-}
-
-
-/*
- *-----------------------------------------------------------------------------
- *-----------------------------------------------------------------------------
- *    Xlock hooks.
- *-----------------------------------------------------------------------------
- *-----------------------------------------------------------------------------
- */
-
-/*
- *-----------------------------------------------------------------------------
- *    Initialize hypertorus.  Called each time the window changes.
- *-----------------------------------------------------------------------------
- */
-
-ENTRYPOINT void init_hypertorus(ModeInfo *mi)
-{
-  hypertorusstruct *hp;
-
-  MI_INIT(mi, hyper);
-  hp = &hyper[MI_SCREEN(mi)];
-
-  hp->trackballs[0] = gltrackball_init(True);
-  hp->trackballs[1] = gltrackball_init(True);
-  hp->current_trackball = 0;
-  hp->button_pressed = False;
-
-  /* Set the display mode. */
-  if (!strcasecmp(mode,"wireframe") || !strcasecmp(mode,"0"))
-  {
-    display_mode = DISP_WIREFRAME;
-  }
-  else if (!strcasecmp(mode,"surface") || !strcasecmp(mode,"1"))
-  {
-    display_mode = DISP_SURFACE;
-  }
-  else if (!strcasecmp(mode,"transparent") || !strcasecmp(mode,"2"))
-  {
-    display_mode = DISP_TRANSPARENT;
-  }
-  else
-  {
-    display_mode = DISP_SURFACE;
-  }
-
-  /* Set the appearance. */
-  if (!strcasecmp(appear,"solid") || !strcasecmp(appear,"0"))
-  {
-    appearance = APPEARANCE_SOLID;
-  }
-  else if (!strcasecmp(appear,"bands") || !strcasecmp(appear,"1"))
-  {
-    appearance = APPEARANCE_BANDS;
-    num_spirals = 0;
-  }
-  else if (!strcasecmp(appear,"spirals-1") || !strcasecmp(appear,"3"))
-  {
-    appearance = APPEARANCE_SPIRALS;
-    num_spirals = 1;
-  }
-  else if (!strcasecmp(appear,"spirals-2") || !strcasecmp(appear,"4"))
-  {
-    appearance = APPEARANCE_SPIRALS;
-    num_spirals = 2;
-  }
-  else if (!strcasecmp(appear,"spirals-4") || !strcasecmp(appear,"5"))
-  {
-    appearance = APPEARANCE_SPIRALS;
-    num_spirals = 4;
-  }
-  else if (!strcasecmp(appear,"spirals-8") || !strcasecmp(appear,"6"))
-  {
-    appearance = APPEARANCE_SPIRALS;
-    num_spirals = 8;
-  }
-  else if (!strcasecmp(appear,"spirals-16") || !strcasecmp(appear,"7"))
-  {
-    appearance = APPEARANCE_SPIRALS;
-    num_spirals = 16;
-  }
-  else
-  {
-    appearance = APPEARANCE_BANDS;
-    num_spirals = 0;
-  }
-
-  /* Set the color mode. */
-  if (!strcasecmp(color_mode,"onesided"))
-  {
-    colors = COLORS_ONESIDED;
-  }
-  else if (!strcasecmp(color_mode,"twosided"))
-  {
-    colors = COLORS_TWOSIDED;
-  }
-  else if (!strcasecmp(color_mode,"colorwheel"))
-  {
-    colors = COLORS_COLORWHEEL;
-  }
-  else
-  {
-    colors = COLORS_COLORWHEEL;
-  }
-
-  /* Set the 3d projection mode. */
-  if (!strcasecmp(proj_3d,"perspective") || !strcasecmp(proj_3d,"0"))
-  {
-    projection_3d = DISP_3D_PERSPECTIVE;
-  }
-  else if (!strcasecmp(proj_3d,"orthographic") || !strcasecmp(proj_3d,"1"))
-  {
-    projection_3d = DISP_3D_ORTHOGRAPHIC;
-  }
-  else
-  {
-    projection_3d = DISP_3D_PERSPECTIVE;
-  }
-
-  /* Set the 4d projection mode. */
-  if (!strcasecmp(proj_4d,"perspective") || !strcasecmp(proj_4d,"0"))
-  {
-    projection_4d = DISP_4D_PERSPECTIVE;
-  }
-  else if (!strcasecmp(proj_4d,"orthographic") || !strcasecmp(proj_4d,"1"))
-  {
-    projection_4d = DISP_4D_ORTHOGRAPHIC;
-  }
-  else
-  {
-    projection_4d = DISP_4D_PERSPECTIVE;
-  }
-
-  /* make multiple screens rotate at slightly different rates. */
-  hp->speed_scale = 0.9 + frand(0.3);
-
-  if ((hp->glx_context = init_GL(mi)) != NULL)
-  {
-    reshape_hypertorus(mi,MI_WIDTH(mi),MI_HEIGHT(mi));
-    init(mi);
-  }
-  else
-  {
-    MI_CLEARWINDOW(mi);
-  }
-}
-
-/*
- *-----------------------------------------------------------------------------
- *    Called by the mainline code periodically to update the display.
- *-----------------------------------------------------------------------------
- */
-ENTRYPOINT void draw_hypertorus(ModeInfo *mi)
-{
-  Display          *display = MI_DISPLAY(mi);
-  Window           window = MI_WINDOW(mi);
-  hypertorusstruct *hp;
-
-  if (hyper == NULL)
-    return;
-  hp = &hyper[MI_SCREEN(mi)];
-
-  MI_IS_DRAWN(mi) = True;
-  if (!hp->glx_context)
-    return;
-
-  glXMakeCurrent(display, window, *hp->glx_context);
-
-  glClearColor(0.0f,0.0f,0.0f,1.0f);
-  glClearDepth(1.0f);
-  glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
-
-  display_hypertorus(mi);
-
-  if (MI_IS_FPS(mi))
-    do_fps (mi);
-
-  glFlush();
-
-  glXSwapBuffers(display,window);
-}
-
-
-#ifndef STANDALONE
-ENTRYPOINT void change_hypertorus(ModeInfo *mi)
-{
-  hypertorusstruct *hp = &hyper[MI_SCREEN(mi)];
-
-  if (!hp->glx_context)
-    return;
-
-  glXMakeCurrent(MI_DISPLAY(mi), MI_WINDOW(mi), *hp->glx_context);
-  init(mi);
-}
-#endif /* !STANDALONE */
-
-
-ENTRYPOINT void free_hypertorus(ModeInfo *mi)
-{
-  hypertorusstruct *hp = &hyper[MI_SCREEN(mi)];
-  if (!hp->glx_context) return;
-  glXMakeCurrent (MI_DISPLAY(mi), MI_WINDOW(mi), *hp->glx_context);
-  gltrackball_free (hp->trackballs[0]);
-  gltrackball_free (hp->trackballs[1]);
-#ifdef HAVE_GLSL
-  if (hp->use_shaders)
-  {
-    glDeleteBuffers(1,&hp->vertex_uv_buffer);
-    glDeleteBuffers(1,&hp->color_buffer);
-    glDeleteBuffers(1,&hp->indices_buffer);
-    if (hp->shader_program != 0)
-    {
-      glUseProgram(0);
-      glDeleteProgram(hp->shader_program);
-    }
-  }
-#endif /* HAVE_GLSL */
-}
-
-
-XSCREENSAVER_MODULE ("Hypertorus", hypertorus)
-
-#endif /* USE_GL */