opengl/glesgears.c - mendel-testing-tools - Git at Google

 /*
  * Copyright (C) 1999-2001  Brian Paul   All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included
  * in all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 /* Conversion to use vertex buffer objects by Michael J. Clark */

 /*
  * Port to Mendel Linux Wayland by Peter Nordström 1 June 2020
  *
  * Window handling and egl initialization done externally in
  * simple-egl.c
  */

 #include <assert.h>
 #include <GLES/gl.h>
 #include <math.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>

 extern void HandleFrame(void);

 #ifndef M_PI
 #define M_PI 3.14159265
 #endif

 static GLfloat viewDist = 40.0;

 typedef struct {
   GLfloat pos[3];
   GLfloat norm[3];
 } vertex_t;

 typedef struct {
   vertex_t *vertices;
   GLushort *indices;
   GLfloat color[4];
   int nvertices, nindices;
   GLuint ibo;
 } gear_t;

 static gear_t *red_gear;
 static gear_t *green_gear;
 static gear_t *blue_gear;

 /**

   Draw a gear wheel.  You'll probably want to call this function when
   building a display list since we do a lot of trig here.

   Input:  inner_radius - radius of hole at center
           outer_radius - radius at center of teeth
           width - width of gear
           teeth - number of teeth
           tooth_depth - depth of tooth

  **/

 static gear_t*
 gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
      GLint teeth, GLfloat tooth_depth, GLfloat color[])
 {
   GLint i, j;
   GLfloat r0, r1, r2;
   GLfloat ta, da;
   GLfloat u1, v1, u2, v2, len;
   GLfloat cos_ta, cos_ta_1da, cos_ta_2da, cos_ta_3da, cos_ta_4da;
   GLfloat sin_ta, sin_ta_1da, sin_ta_2da, sin_ta_3da, sin_ta_4da;
   GLushort ix0, ix1, ix2, ix3, ix4, ix5;
   vertex_t *vt, *nm;
   GLushort *ix;

   gear_t *gear = calloc(1, sizeof(gear_t));
   gear->nvertices = teeth * 40;
   gear->nindices = teeth * 66 * 3;
   gear->vertices = calloc(gear->nvertices, sizeof(vertex_t));
   gear->indices = calloc(gear->nindices, sizeof(GLushort));
   memcpy(&gear->color[0], &color[0], sizeof(GLfloat) * 4);


   r0 = inner_radius;
   r1 = outer_radius - tooth_depth / 2.0;
   r2 = outer_radius + tooth_depth / 2.0;
   da = 2.0 * M_PI / teeth / 4.0;

   vt = gear->vertices;
   nm = gear->vertices;
   ix = gear->indices;

 #define VERTEX(x,y,z) ((vt->pos[0] = x),(vt->pos[1] = y),(vt->pos[2] = z), \
                        (vt++ - gear->vertices))
 #define NORMAL(x,y,z) ((nm->norm[0] = x),(nm->norm[1] = y),(nm->norm[2] = z), \
                        (nm++ - gear->vertices))
 #define INDEX(a,b,c) ((*ix++ = a),(*ix++ = b),(*ix++ = c))

   for (i = 0; i < teeth; i++) {
     ta = i * 2.0 * M_PI / (teeth);

     cos_ta = cos(ta);
     cos_ta_1da = cos(ta + da);
     cos_ta_2da = cos(ta + 2 * da);
     cos_ta_3da = cos(ta + 3 * da);
     cos_ta_4da = cos(ta + 4 * da);
     sin_ta = sin(ta);
     sin_ta_1da = sin(ta + da);
     sin_ta_2da = sin(ta + 2 * da);
     sin_ta_3da = sin(ta + 3 * da);
     sin_ta_4da = sin(ta + 4 * da);

     u1 = r2 * cos_ta_1da - r1 * cos_ta;
     v1 = r2 * sin_ta_1da - r1 * sin_ta;
     len = sqrt(u1 * u1 + v1 * v1);
     u1 /= len;
     v1 /= len;
     u2 = r1 * cos_ta_3da - r2 * cos_ta_2da;
     v2 = r1 * sin_ta_3da - r2 * sin_ta_2da;

     /* front face */
     ix0 = VERTEX(r0 * cos_ta,          r0 * sin_ta,          width * 0.5);
     ix1 = VERTEX(r1 * cos_ta,          r1 * sin_ta,          width * 0.5);
     ix2 = VERTEX(r0 * cos_ta_2da,      r0 * sin_ta_2da,      width * 0.5);
     ix3 = VERTEX(r1 * cos_ta_2da,      r1 * sin_ta_2da,      width * 0.5);
     ix4 = VERTEX(r0 * cos_ta_4da,      r0 * sin_ta_4da,      width * 0.5);
     ix5 = VERTEX(r1 * cos_ta_4da,      r1 * sin_ta_4da,      width * 0.5);
     for (j = 0; j < 6; j++) {
       NORMAL(0.0,                  0.0,                  1.0);
     }
     INDEX(ix0, ix1, ix2);
     INDEX(ix1, ix3, ix2);
     INDEX(ix2, ix3, ix4);
     INDEX(ix3, ix5, ix4);

     /* front sides of teeth */
     ix0 = VERTEX(r1 * cos_ta,          r1 * sin_ta,          width * 0.5);
     ix1 = VERTEX(r2 * cos_ta_1da,      r2 * sin_ta_1da,      width * 0.5);
     ix2 = VERTEX(r1 * cos_ta_3da,      r1 * sin_ta_3da,      width * 0.5);
     ix3 = VERTEX(r2 * cos_ta_2da,      r2 * sin_ta_2da,      width * 0.5);
     for (j = 0; j < 4; j++) {
       NORMAL(0.0,                  0.0,                  1.0);
     }
     INDEX(ix0, ix1, ix2);
     INDEX(ix1, ix3, ix2);

     /* back face */
     ix0 = VERTEX(r0 * cos_ta,          r0 * sin_ta,          -width * 0.5);
     ix1 = VERTEX(r1 * cos_ta,          r1 * sin_ta,          -width * 0.5);
     ix2 = VERTEX(r0 * cos_ta_2da,      r0 * sin_ta_2da,      -width * 0.5);
     ix3 = VERTEX(r1 * cos_ta_2da,      r1 * sin_ta_2da,      -width * 0.5);
     ix4 = VERTEX(r0 * cos_ta_4da,      r0 * sin_ta_4da,      -width * 0.5);
     ix5 = VERTEX(r1 * cos_ta_4da,      r1 * sin_ta_4da,      -width * 0.5);
     for (j = 0; j < 6; j++) {
       NORMAL(0.0,                  0.0,                  -1.0);
     }
     INDEX(ix0, ix1, ix2);
     INDEX(ix1, ix3, ix2);
     INDEX(ix2, ix3, ix4);
     INDEX(ix3, ix5, ix4);

     /* back sides of teeth */
     ix0 = VERTEX(r1 * cos_ta_3da,      r1 * sin_ta_3da,      -width * 0.5);
     ix1 = VERTEX(r2 * cos_ta_2da,      r2 * sin_ta_2da,      -width * 0.5);
     ix2 = VERTEX(r1 * cos_ta,          r1 * sin_ta,          -width * 0.5);
     ix3 = VERTEX(r2 * cos_ta_1da,      r2 * sin_ta_1da,      -width * 0.5);
     for (j = 0; j < 4; j++) {
       NORMAL(0.0,                  0.0,                  -1.0);
     }
     INDEX(ix0, ix1, ix2);
     INDEX(ix1, ix3, ix2);

     /* draw outward faces of teeth */
     ix0 = VERTEX(r1 * cos_ta,          r1 * sin_ta,          width * 0.5);
     ix1 = VERTEX(r1 * cos_ta,          r1 * sin_ta,          -width * 0.5);
     ix2 = VERTEX(r2 * cos_ta_1da,      r2 * sin_ta_1da,      width * 0.5);
     ix3 = VERTEX(r2 * cos_ta_1da,      r2 * sin_ta_1da,      -width * 0.5);
     for (j = 0; j < 4; j++) {
       NORMAL(v1,                   -u1,                  0.0);
     }
     INDEX(ix0, ix1, ix2);
     INDEX(ix1, ix3, ix2);
     ix0 = VERTEX(r2 * cos_ta_1da,      r2 * sin_ta_1da,      width * 0.5);
     ix1 = VERTEX(r2 * cos_ta_1da,      r2 * sin_ta_1da,      -width * 0.5);
     ix2 = VERTEX(r2 * cos_ta_2da,      r2 * sin_ta_2da,      width * 0.5);
     ix3 = VERTEX(r2 * cos_ta_2da,      r2 * sin_ta_2da,      -width * 0.5);
     for (j = 0; j < 4; j++) {
       NORMAL(cos_ta,               sin_ta,               0.0);
     }
     INDEX(ix0, ix1, ix2);
     INDEX(ix1, ix3, ix2);
     ix0 = VERTEX(r2 * cos_ta_2da,      r2 * sin_ta_2da,      width * 0.5);
     ix1 = VERTEX(r2 * cos_ta_2da,      r2 * sin_ta_2da,      -width * 0.5);
     ix2 = VERTEX(r1 * cos_ta_3da,      r1 * sin_ta_3da,      width * 0.5);
     ix3 = VERTEX(r1 * cos_ta_3da,      r1 * sin_ta_3da,      -width * 0.5);
     for (j = 0; j < 4; j++) {
       NORMAL(v2,                   -u2,                  0.0);
     }
     INDEX(ix0, ix1, ix2);
     INDEX(ix1, ix3, ix2);
     ix0 = VERTEX(r1 * cos_ta_3da,      r1 * sin_ta_3da,      width * 0.5);
     ix1 = VERTEX(r1 * cos_ta_3da,      r1 * sin_ta_3da,      -width * 0.5);
     ix2 = VERTEX(r1 * cos_ta_4da,      r1 * sin_ta_4da,      width * 0.5);
     ix3 = VERTEX(r1 * cos_ta_4da,      r1 * sin_ta_4da,      -width * 0.5);
     for (j = 0; j < 4; j++) {
       NORMAL(cos_ta,               sin_ta,               0.0);
     }
     INDEX(ix0, ix1, ix2);
     INDEX(ix1, ix3, ix2);

     /* draw inside radius cylinder */
     ix0 = VERTEX(r0 * cos_ta,          r0 * sin_ta,          -width * 0.5);
     ix1 = VERTEX(r0 * cos_ta,          r0 * sin_ta,          width * 0.5);
     ix2 = VERTEX(r0 * cos_ta_4da,      r0 * sin_ta_4da,      -width * 0.5);
     ix3 = VERTEX(r0 * cos_ta_4da,      r0 * sin_ta_4da,      width * 0.5);
     NORMAL(-cos_ta,              -sin_ta,              0.0);
     NORMAL(-cos_ta,              -sin_ta,              0.0);
     NORMAL(-cos_ta_4da,          -sin_ta_4da,          0.0);
     NORMAL(-cos_ta_4da,          -sin_ta_4da,          0.0);
     INDEX(ix0, ix1, ix2);
     INDEX(ix1, ix3, ix2);
   }

   return gear;
 }


 void draw_gear(gear_t* gear) {
   glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, gear->color);
   glVertexPointer(3, GL_FLOAT, sizeof(vertex_t), gear->vertices[0].pos);
   glNormalPointer(GL_FLOAT, sizeof(vertex_t), gear->vertices[0].norm);
   glDrawElements(GL_TRIANGLES, gear->nindices/3, GL_UNSIGNED_SHORT,
                  gear->indices);
 }

 static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
 static gear_t *gear1, *gear2, *gear3;
 static GLfloat angle = 0.0;

 static void
 draw(void)
 {
   glClearColor(0.0, 0.0, 0.0, 0.0);
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

   glPushMatrix();

   glTranslatef(0.0, 0.0, -viewDist);

   glRotatef(view_rotx, 1.0, 0.0, 0.0);
   glRotatef(view_roty, 0.0, 1.0, 0.0);
   glRotatef(view_rotz, 0.0, 0.0, 1.0);

   glPushMatrix();
   glTranslatef(-3.0, -2.0, 0.0);
   glRotatef(angle, 0.0, 0.0, 1.0);
   draw_gear(gear1);
   glPopMatrix();

   glPushMatrix();
   glTranslatef(3.1, -2.0, 0.0);
   glRotatef(-2.0 * angle - 9.0, 0.0, 0.0, 1.0);
   draw_gear(gear2);
   glPopMatrix();

   glPushMatrix();
   glTranslatef(-3.1, 4.2, 0.0);
   glRotatef(-2.0 * angle - 25.0, 0.0, 0.0, 1.0);
   draw_gear(gear3);
   glPopMatrix();

   glPopMatrix();
 }

 /* new window size or exposure */
 static void
 reshape(int width, int height)
 {
   GLfloat h = (GLfloat) height / (GLfloat) width;

   glViewport(0, 0, (GLint) width, (GLint) height);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glFrustumf(-1.0, 1.0, -h, h, 5.0, 200.0);
   glMatrixMode(GL_MODELVIEW);
 }

 void initialize() {
   glShadeModel(GL_SMOOTH);
   glEnableClientState(GL_NORMAL_ARRAY);
   glEnableClientState(GL_VERTEX_ARRAY);

   static GLfloat pos[4] = {5.0, 5.0, 10.0, 0.0};
   static GLfloat red[4] = {0.8, 0.1, 0.0, 1.0};
   static GLfloat green[4] = {0.0, 0.8, 0.2, 1.0};
   static GLfloat blue[4] = {0.2, 0.2, 1.0, 1.0};

   glLightfv(GL_LIGHT0, GL_POSITION, pos);
   glEnable(GL_CULL_FACE);
   glEnable(GL_LIGHTING);
   glEnable(GL_LIGHT0);
   glEnable(GL_DEPTH_TEST);

   /* make the gears */
   gear1 = gear(1.0, 4.0, 1.0, 20, 0.7, red);
   gear2 = gear(0.5, 2.0, 2.0, 10, 0.7, green);
   gear3 = gear(1.3, 2.0, 0.5, 10, 0.7, blue);
 }

 void RunGears() {
   double dt = 0.01666;

   initialize();
   reshape(600, 600);

   while (1) {
     dt = 0.01666;

     /* advance rotation for next frame */
     angle += 70.0 * dt;  /* 70 degrees per second */
     if (angle > 3600.0)
       angle -= 3600.0;

     draw();
     HandleFrame();
   }
 }
	/*
	* Copyright (C) 1999-2001 Brian Paul All Rights Reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included
	* in all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
	* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
	* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
	* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*/
	/* Conversion to use vertex buffer objects by Michael J. Clark */

	/*
	* Port to Mendel Linux Wayland by Peter Nordström 1 June 2020
	*
	* Window handling and egl initialization done externally in
	* simple-egl.c
	*/

	#include <assert.h>
	#include <GLES/gl.h>
	#include <math.h>
	#include <stdlib.h>
	#include <string.h>
	#include <unistd.h>

	extern void HandleFrame(void);

	#ifndef M_PI
	#define M_PI 3.14159265
	#endif

	static GLfloat viewDist = 40.0;

	typedef struct {
	GLfloat pos[3];
	GLfloat norm[3];
	} vertex_t;

	typedef struct {
	vertex_t *vertices;
	GLushort *indices;
	GLfloat color[4];
	int nvertices, nindices;
	GLuint ibo;
	} gear_t;

	static gear_t *red_gear;
	static gear_t *green_gear;
	static gear_t *blue_gear;

	/**

	Draw a gear wheel. You'll probably want to call this function when
	building a display list since we do a lot of trig here.

	Input: inner_radius - radius of hole at center
	outer_radius - radius at center of teeth
	width - width of gear
	teeth - number of teeth
	tooth_depth - depth of tooth

	**/

	static gear_t*
	gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
	GLint teeth, GLfloat tooth_depth, GLfloat color[])
	{
	GLint i, j;
	GLfloat r0, r1, r2;
	GLfloat ta, da;
	GLfloat u1, v1, u2, v2, len;
	GLfloat cos_ta, cos_ta_1da, cos_ta_2da, cos_ta_3da, cos_ta_4da;
	GLfloat sin_ta, sin_ta_1da, sin_ta_2da, sin_ta_3da, sin_ta_4da;
	GLushort ix0, ix1, ix2, ix3, ix4, ix5;
	vertex_t vt, nm;
	GLushort *ix;

	gear_t *gear = calloc(1, sizeof(gear_t));
	gear->nvertices = teeth * 40;
	gear->nindices = teeth * 66 * 3;
	gear->vertices = calloc(gear->nvertices, sizeof(vertex_t));
	gear->indices = calloc(gear->nindices, sizeof(GLushort));
	memcpy(&gear->color[0], &color[0], sizeof(GLfloat) * 4);


	r0 = inner_radius;
	r1 = outer_radius - tooth_depth / 2.0;
	r2 = outer_radius + tooth_depth / 2.0;
	da = 2.0 * M_PI / teeth / 4.0;

	vt = gear->vertices;
	nm = gear->vertices;
	ix = gear->indices;

	#define VERTEX(x,y,z) ((vt->pos[0] = x),(vt->pos[1] = y),(vt->pos[2] = z), \
	(vt++ - gear->vertices))
	#define NORMAL(x,y,z) ((nm->norm[0] = x),(nm->norm[1] = y),(nm->norm[2] = z), \
	(nm++ - gear->vertices))
	#define INDEX(a,b,c) ((ix++ = a),(ix++ = b),(*ix++ = c))

	for (i = 0; i < teeth; i++) {
	ta = i * 2.0 * M_PI / (teeth);

	cos_ta = cos(ta);
	cos_ta_1da = cos(ta + da);
	cos_ta_2da = cos(ta + 2 * da);
	cos_ta_3da = cos(ta + 3 * da);
	cos_ta_4da = cos(ta + 4 * da);
	sin_ta = sin(ta);
	sin_ta_1da = sin(ta + da);
	sin_ta_2da = sin(ta + 2 * da);
	sin_ta_3da = sin(ta + 3 * da);
	sin_ta_4da = sin(ta + 4 * da);

	u1 = r2 * cos_ta_1da - r1 * cos_ta;
	v1 = r2 * sin_ta_1da - r1 * sin_ta;
	len = sqrt(u1 * u1 + v1 * v1);
	u1 /= len;
	v1 /= len;
	u2 = r1 * cos_ta_3da - r2 * cos_ta_2da;
	v2 = r1 * sin_ta_3da - r2 * sin_ta_2da;

	/* front face */
	ix0 = VERTEX(r0 * cos_ta, r0 * sin_ta, width * 0.5);
	ix1 = VERTEX(r1 * cos_ta, r1 * sin_ta, width * 0.5);
	ix2 = VERTEX(r0 * cos_ta_2da, r0 * sin_ta_2da, width * 0.5);
	ix3 = VERTEX(r1 * cos_ta_2da, r1 * sin_ta_2da, width * 0.5);
	ix4 = VERTEX(r0 * cos_ta_4da, r0 * sin_ta_4da, width * 0.5);
	ix5 = VERTEX(r1 * cos_ta_4da, r1 * sin_ta_4da, width * 0.5);
	for (j = 0; j < 6; j++) {
	NORMAL(0.0, 0.0, 1.0);
	}
	INDEX(ix0, ix1, ix2);
	INDEX(ix1, ix3, ix2);
	INDEX(ix2, ix3, ix4);
	INDEX(ix3, ix5, ix4);

	/* front sides of teeth */
	ix0 = VERTEX(r1 * cos_ta, r1 * sin_ta, width * 0.5);
	ix1 = VERTEX(r2 * cos_ta_1da, r2 * sin_ta_1da, width * 0.5);
	ix2 = VERTEX(r1 * cos_ta_3da, r1 * sin_ta_3da, width * 0.5);
	ix3 = VERTEX(r2 * cos_ta_2da, r2 * sin_ta_2da, width * 0.5);
	for (j = 0; j < 4; j++) {
	NORMAL(0.0, 0.0, 1.0);
	}
	INDEX(ix0, ix1, ix2);
	INDEX(ix1, ix3, ix2);

	/* back face */
	ix0 = VERTEX(r0 * cos_ta, r0 * sin_ta, -width * 0.5);
	ix1 = VERTEX(r1 * cos_ta, r1 * sin_ta, -width * 0.5);
	ix2 = VERTEX(r0 * cos_ta_2da, r0 * sin_ta_2da, -width * 0.5);
	ix3 = VERTEX(r1 * cos_ta_2da, r1 * sin_ta_2da, -width * 0.5);
	ix4 = VERTEX(r0 * cos_ta_4da, r0 * sin_ta_4da, -width * 0.5);
	ix5 = VERTEX(r1 * cos_ta_4da, r1 * sin_ta_4da, -width * 0.5);
	for (j = 0; j < 6; j++) {
	NORMAL(0.0, 0.0, -1.0);
	}
	INDEX(ix0, ix1, ix2);
	INDEX(ix1, ix3, ix2);
	INDEX(ix2, ix3, ix4);
	INDEX(ix3, ix5, ix4);

	/* back sides of teeth */
	ix0 = VERTEX(r1 * cos_ta_3da, r1 * sin_ta_3da, -width * 0.5);
	ix1 = VERTEX(r2 * cos_ta_2da, r2 * sin_ta_2da, -width * 0.5);
	ix2 = VERTEX(r1 * cos_ta, r1 * sin_ta, -width * 0.5);
	ix3 = VERTEX(r2 * cos_ta_1da, r2 * sin_ta_1da, -width * 0.5);
	for (j = 0; j < 4; j++) {
	NORMAL(0.0, 0.0, -1.0);
	}
	INDEX(ix0, ix1, ix2);
	INDEX(ix1, ix3, ix2);

	/* draw outward faces of teeth */
	ix0 = VERTEX(r1 * cos_ta, r1 * sin_ta, width * 0.5);
	ix1 = VERTEX(r1 * cos_ta, r1 * sin_ta, -width * 0.5);
	ix2 = VERTEX(r2 * cos_ta_1da, r2 * sin_ta_1da, width * 0.5);
	ix3 = VERTEX(r2 * cos_ta_1da, r2 * sin_ta_1da, -width * 0.5);
	for (j = 0; j < 4; j++) {
	NORMAL(v1, -u1, 0.0);
	}
	INDEX(ix0, ix1, ix2);
	INDEX(ix1, ix3, ix2);
	ix0 = VERTEX(r2 * cos_ta_1da, r2 * sin_ta_1da, width * 0.5);
	ix1 = VERTEX(r2 * cos_ta_1da, r2 * sin_ta_1da, -width * 0.5);
	ix2 = VERTEX(r2 * cos_ta_2da, r2 * sin_ta_2da, width * 0.5);
	ix3 = VERTEX(r2 * cos_ta_2da, r2 * sin_ta_2da, -width * 0.5);
	for (j = 0; j < 4; j++) {
	NORMAL(cos_ta, sin_ta, 0.0);
	}
	INDEX(ix0, ix1, ix2);
	INDEX(ix1, ix3, ix2);
	ix0 = VERTEX(r2 * cos_ta_2da, r2 * sin_ta_2da, width * 0.5);
	ix1 = VERTEX(r2 * cos_ta_2da, r2 * sin_ta_2da, -width * 0.5);
	ix2 = VERTEX(r1 * cos_ta_3da, r1 * sin_ta_3da, width * 0.5);
	ix3 = VERTEX(r1 * cos_ta_3da, r1 * sin_ta_3da, -width * 0.5);
	for (j = 0; j < 4; j++) {
	NORMAL(v2, -u2, 0.0);
	}
	INDEX(ix0, ix1, ix2);
	INDEX(ix1, ix3, ix2);
	ix0 = VERTEX(r1 * cos_ta_3da, r1 * sin_ta_3da, width * 0.5);
	ix1 = VERTEX(r1 * cos_ta_3da, r1 * sin_ta_3da, -width * 0.5);
	ix2 = VERTEX(r1 * cos_ta_4da, r1 * sin_ta_4da, width * 0.5);
	ix3 = VERTEX(r1 * cos_ta_4da, r1 * sin_ta_4da, -width * 0.5);
	for (j = 0; j < 4; j++) {
	NORMAL(cos_ta, sin_ta, 0.0);
	}
	INDEX(ix0, ix1, ix2);
	INDEX(ix1, ix3, ix2);

	/* draw inside radius cylinder */
	ix0 = VERTEX(r0 * cos_ta, r0 * sin_ta, -width * 0.5);
	ix1 = VERTEX(r0 * cos_ta, r0 * sin_ta, width * 0.5);
	ix2 = VERTEX(r0 * cos_ta_4da, r0 * sin_ta_4da, -width * 0.5);
	ix3 = VERTEX(r0 * cos_ta_4da, r0 * sin_ta_4da, width * 0.5);
	NORMAL(-cos_ta, -sin_ta, 0.0);
	NORMAL(-cos_ta, -sin_ta, 0.0);
	NORMAL(-cos_ta_4da, -sin_ta_4da, 0.0);
	NORMAL(-cos_ta_4da, -sin_ta_4da, 0.0);
	INDEX(ix0, ix1, ix2);
	INDEX(ix1, ix3, ix2);
	}

	return gear;
	}


	void draw_gear(gear_t* gear) {
	glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, gear->color);
	glVertexPointer(3, GL_FLOAT, sizeof(vertex_t), gear->vertices[0].pos);
	glNormalPointer(GL_FLOAT, sizeof(vertex_t), gear->vertices[0].norm);
	glDrawElements(GL_TRIANGLES, gear->nindices/3, GL_UNSIGNED_SHORT,
	gear->indices);
	}

	static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
	static gear_t gear1, gear2, *gear3;
	static GLfloat angle = 0.0;

	static void
	draw(void)
	{
	glClearColor(0.0, 0.0, 0.0, 0.0);
	glClear(GL_COLOR_BUFFER_BIT \| GL_DEPTH_BUFFER_BIT);

	glPushMatrix();

	glTranslatef(0.0, 0.0, -viewDist);

	glRotatef(view_rotx, 1.0, 0.0, 0.0);
	glRotatef(view_roty, 0.0, 1.0, 0.0);
	glRotatef(view_rotz, 0.0, 0.0, 1.0);

	glPushMatrix();
	glTranslatef(-3.0, -2.0, 0.0);
	glRotatef(angle, 0.0, 0.0, 1.0);
	draw_gear(gear1);
	glPopMatrix();

	glPushMatrix();
	glTranslatef(3.1, -2.0, 0.0);
	glRotatef(-2.0 * angle - 9.0, 0.0, 0.0, 1.0);
	draw_gear(gear2);
	glPopMatrix();

	glPushMatrix();
	glTranslatef(-3.1, 4.2, 0.0);
	glRotatef(-2.0 * angle - 25.0, 0.0, 0.0, 1.0);
	draw_gear(gear3);
	glPopMatrix();

	glPopMatrix();
	}

	/* new window size or exposure */
	static void
	reshape(int width, int height)
	{
	GLfloat h = (GLfloat) height / (GLfloat) width;

	glViewport(0, 0, (GLint) width, (GLint) height);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glFrustumf(-1.0, 1.0, -h, h, 5.0, 200.0);
	glMatrixMode(GL_MODELVIEW);
	}

	void initialize() {
	glShadeModel(GL_SMOOTH);
	glEnableClientState(GL_NORMAL_ARRAY);
	glEnableClientState(GL_VERTEX_ARRAY);

	static GLfloat pos[4] = {5.0, 5.0, 10.0, 0.0};
	static GLfloat red[4] = {0.8, 0.1, 0.0, 1.0};
	static GLfloat green[4] = {0.0, 0.8, 0.2, 1.0};
	static GLfloat blue[4] = {0.2, 0.2, 1.0, 1.0};

	glLightfv(GL_LIGHT0, GL_POSITION, pos);
	glEnable(GL_CULL_FACE);
	glEnable(GL_LIGHTING);
	glEnable(GL_LIGHT0);
	glEnable(GL_DEPTH_TEST);

	/* make the gears */
	gear1 = gear(1.0, 4.0, 1.0, 20, 0.7, red);
	gear2 = gear(0.5, 2.0, 2.0, 10, 0.7, green);
	gear3 = gear(1.3, 2.0, 0.5, 10, 0.7, blue);
	}

	void RunGears() {
	double dt = 0.01666;

	initialize();
	reshape(600, 600);

	while (1) {
	dt = 0.01666;

	/* advance rotation for next frame */
	angle += 70.0 * dt; /* 70 degrees per second */
	if (angle > 3600.0)
	angle -= 3600.0;

	draw();
	HandleFrame();
	}
	}