/*
* taper.c
*
* FUNCTION:
* Draws a tapered screw shape.
*
* HISTORY:
* -- created by Linas Vepstas October 1991
* -- heavily modified to draw more texas shapes, Feb 1993, Linas
* -- converted to use GLUT -- December 1995, Linas
*
*/
#include "extrusion.h"
#include <math.h>
#include <stdlib.h>
#ifndef NULL
#define NULL ((void *) 0x0)
#endif /* NULL */
/* Some <math.h> files do not define M_PI... */
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
/* =========================================================== */
#define SCALE 3.33333
#define CONTOUR(x,y) { \
double ax, ay, alen; \
contour[i][0] = SCALE * (x); \
contour[i][1] = SCALE * (y); \
if (i!=0) { \
ax = contour[i][0] - contour[i-1][0]; \
ay = contour[i][1] - contour[i-1][1]; \
alen = 1.0 / sqrt (ax*ax + ay*ay); \
ax *= alen; ay *= alen; \
norms [i-1][0] = ay; \
norms [i-1][1] = -ax; \
} \
i++; \
}
#define NUM_PTS (25)
static double contour [NUM_PTS][2];
static double norms [NUM_PTS][2];
static void init_contour (void)
{
int i;
/* outline of extrusion */
i=0;
CONTOUR (1.0, 1.0);
CONTOUR (1.0, 2.9);
CONTOUR (0.9, 3.0);
CONTOUR (-0.9, 3.0);
CONTOUR (-1.0, 2.9);
CONTOUR (-1.0, 1.0);
CONTOUR (-2.9, 1.0);
CONTOUR (-3.0, 0.9);
CONTOUR (-3.0, -0.9);
CONTOUR (-2.9, -1.0);
CONTOUR (-1.0, -1.0);
CONTOUR (-1.0, -2.9);
CONTOUR (-0.9, -3.0);
CONTOUR (0.9, -3.0);
CONTOUR (1.0, -2.9);
CONTOUR (1.0, -1.0);
CONTOUR (2.9, -1.0);
CONTOUR (3.0, -0.9);
CONTOUR (3.0, 0.9);
CONTOUR (2.9, 1.0);
CONTOUR (1.0, 1.0); /* repeat so that last normal is computed */
}
/* =========================================================== */
#define PSIZE 40
static double path[PSIZE][3];
static double twist[PSIZE];
static double taper[PSIZE];
static void init_taper (void) {
int j;
double z, deltaz;
double ang, dang;
z = -10.0;
deltaz = 0.5;
ang = 0.0;
dang = 20.0;
for (j=0; j<40; j++) {
path[j][0] = 0x0;
path[j][1] = 0x0;
path[j][2] = z;
twist[j] = ang;
ang += dang;
taper[j] = 0.1 * sqrt (9.51*9.51 - z*z);
z += deltaz;
}
taper[0] = taper[1];
taper[39] = taper[38];
}
/* =========================================================== */
/* controls shape of object */
extern float lastx;
extern float lasty;
void InitStuff_taper (void)
{
int style;
/* configure the pipeline */
style = TUBE_JN_CAP;
style |= TUBE_CONTOUR_CLOSED;
style |= TUBE_NORM_FACET;
style |= TUBE_JN_ANGLE;
gleSetJoinStyle (style);
init_contour();
init_taper();
}
/* =========================================================== */
static void gleTaper (int ncp,
gleDouble contour[][2],
gleDouble cont_normal[][2],
gleDouble up[3],
int npoints,
gleDouble point_array[][3],
float color_array[][3],
gleDouble taper[],
gleDouble twist[])
{
int j;
gleAffine *xforms;
double co, si, angle;
/* malloc the extrusion array and the twist array */
xforms = (gleAffine *) malloc (npoints * sizeof(gleAffine));
for (j=0; j<npoints; j++) {
angle = (M_PI/180.0) * twist[j];
si = sin (angle);
co = cos (angle);
xforms[j][0][0] = taper[j] * co;
xforms[j][0][1] = - taper[j] * si;
xforms[j][0][2] = 0.0;
xforms[j][1][0] = taper[j] * si;
xforms[j][1][1] = taper[j] * co;
xforms[j][1][2] = 0.0;
}
gleSuperExtrusion (ncp, /* number of contour points */
contour, /* 2D contour */
cont_normal, /* 2D contour normals */
up, /* up vector for contour */
npoints, /* numpoints in poly-line */
point_array, /* polyline */
color_array, /* color of polyline */
xforms);
free (xforms);
}
/* =========================================================== */
void DrawStuff_taper (void) {
int j;
double ang, dang;
double z, deltaz;
double ponent;
z=-1.0;
deltaz = 1.999/38;
ang = 0.0;
dang = lasty/40.0;
ponent = fabs (lastx/540.0);
for (j=1; j<39; j++) {
twist[j] = ang;
ang += dang;
taper[j] = pow ((1.0 - pow (fabs(z), 1.0/ponent)), ponent);
z += deltaz;
}
glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3f (0.5, 0.6, 0.6);
/* set up some matrices so that the object spins with the mouse */
glPushMatrix ();
/* glTranslatef (0.0, 0.0, -80.0); */
/* glRotatef (130.0, 0.0, 1.0, 0.0); */
/* glRotatef (65.0, 1.0, 0.0, 0.0); */
/* draw the brand and the handle */
gleTaper (20, contour, norms, NULL, 40, path, NULL, taper, twist);
glPopMatrix ();
}
/* ===================== END OF FILE ================== */
