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Diffstat (limited to 'hacks/glx/sphere.c')
| -rw-r--r-- | hacks/glx/sphere.c | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/hacks/glx/sphere.c b/hacks/glx/sphere.c new file mode 100644 index 0000000..dee4541 --- /dev/null +++ b/hacks/glx/sphere.c @@ -0,0 +1,155 @@ +/* sphere, Copyright (c) 2002 Paul Bourke <pbourke@swin.edu.au>, + * Copyright (c) 2010-2014 Jamie Zawinski <jwz@jwz.org> + * Utility function to create a unit sphere in GL. + * + * Permission to use, copy, modify, distribute, and sell this software and its + * documentation for any purpose is hereby granted without fee, provided that + * the above copyright notice appear in all copies and that both that + * copyright notice and this permission notice appear in supporting + * documentation. No representations are made about the suitability of this + * software for any purpose. It is provided "as is" without express or + * implied warranty. + * + * 8-Oct-98: dek Released initial version of "glplanet" + * 21-Mar-01: jwz@jwz.org Broke sphere routine out into its own file. + * 28-Feb-02: jwz@jwz.org New implementation from Paul Bourke: + * http://astronomy.swin.edu.au/~pbourke/opengl/sphere/ + * 21-Aug-10 jwz@jwz.org Converted to use glDrawArrays, for OpenGL ES. + */ + +#include <math.h> +#include <stdlib.h> + +#ifdef HAVE_CONFIG_H +# include "config.h" +#endif + +#ifdef HAVE_COCOA +#elif defined(HAVE_ANDROID) +# include <GLES/gl.h> +#else /* real X11 */ +# include <GL/gl.h> +#endif + +#ifdef HAVE_JWZGLES +# include "jwzgles.h" +#endif /* HAVE_JWZGLES */ + +#include "sphere.h" + +typedef struct { GLfloat x, y, z; } XYZ; + +static int +unit_sphere_1 (int stacks, int slices, int wire_p, int half_p) +{ + int polys = 0; + int i,j; + double theta1, theta2, theta3; + XYZ p, n; + XYZ la = { 0, -1, 0 }, lb = { 0, -1, 0 }; + XYZ c = {0, 0, 0}; /* center */ + double r = 1.0; /* radius */ + int stacks2 = stacks * 2; + int end = (half_p ? stacks/2 : stacks); + + int mode = (wire_p ? GL_LINE_STRIP : GL_TRIANGLE_STRIP); + + int arraysize, out; + struct { XYZ p; XYZ n; GLfloat s, t; } *array; + + if (r < 0) + r = -r; + if (slices < 0) + slices = -slices; + + arraysize = (stacks+1) * (slices+1) * (wire_p ? 4 : 2); + array = (void *) calloc (arraysize, sizeof(*array)); + if (! array) abort(); + out = 0; + + if (slices < 4 || stacks < 2 || r <= 0) + { + mode = GL_POINTS; + array[out++].p = c; + goto END; + } + + for (j = 0; j < end; j++) + { + theta1 = j * (M_PI+M_PI) / stacks2 - M_PI_2; + theta2 = (j + 1) * (M_PI+M_PI) / stacks2 - M_PI_2; + + for (i = slices; i >= 0; i--) + { + theta3 = i * (M_PI+M_PI) / slices; + + if (wire_p) + { + array[out++].p = lb; /* vertex */ + array[out++].p = la; /* vertex */ + } + + n.x = cos (theta2) * cos(theta3); + n.y = sin (theta2); + n.z = cos (theta2) * sin(theta3); + p.x = c.x + r * n.x; + p.y = c.y + r * n.y; + p.z = c.z + r * n.z; + + array[out].p = p; /* vertex */ + array[out].n = n; /* normal */ + array[out].s = i / (GLfloat) slices; /* texture */ + array[out].t = 2*(j+1) / (GLfloat) stacks2; + out++; + + if (wire_p) la = p; + + n.x = cos(theta1) * cos(theta3); + n.y = sin(theta1); + n.z = cos(theta1) * sin(theta3); + p.x = c.x + r * n.x; + p.y = c.y + r * n.y; + p.z = c.z + r * n.z; + + array[out].p = p; /* vertex */ + array[out].n = n; /* normal */ + array[out].s = i / (GLfloat) slices; /* texture */ + array[out].t = 2*j / (GLfloat) stacks2; + out++; + + if (out >= arraysize) abort(); + + if (wire_p) lb = p; + polys++; + } + } + + END: + + glEnableClientState (GL_VERTEX_ARRAY); + glEnableClientState (GL_NORMAL_ARRAY); + glEnableClientState (GL_TEXTURE_COORD_ARRAY); + + glVertexPointer (3, GL_FLOAT, sizeof(*array), &array[0].p); + glNormalPointer ( GL_FLOAT, sizeof(*array), &array[0].n); + glTexCoordPointer (2, GL_FLOAT, sizeof(*array), &array[0].s); + + glDrawArrays (mode, 0, out); + + free (array); + + return polys; +} + + +int +unit_sphere (int stacks, int slices, int wire_p) +{ + return unit_sphere_1 (stacks, slices, wire_p, 0); +} + +int +unit_dome (int stacks, int slices, int wire_p) +{ + return unit_sphere_1 (stacks, slices, wire_p, 1); +} |