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diff --git a/progs/demos/gears.c b/progs/demos/gears.c
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+/* $Id: gears.c,v 1.1 1999/08/19 00:55:40 jtg Exp $ */
+
+/*
+ * 3-D gear wheels. This program is in the public domain.
+ *
+ * Brian Paul
+ */
+
+/* Conversion to GLUT by Mark J. Kilgard */
+
+/*
+ * $Log: gears.c,v $
+ * Revision 1.1 1999/08/19 00:55:40 jtg
+ * Initial revision
+ *
+ * Revision 3.2 1999/06/03 17:07:36 brianp
+ * an extra quad was being drawn in front and back faces
+ *
+ * Revision 3.1 1998/11/03 02:49:10 brianp
+ * added fps output
+ *
+ * Revision 3.0 1998/02/14 18:42:29 brianp
+ * initial rev
+ *
+ */
+
+
+#include <math.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <GL/glut.h>
+
+#ifndef M_PI
+#define M_PI 3.14159265
+#endif
+
+static GLint T0 = 0;
+static GLint Frames = 0;
+
+
+/**
+
+ 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 void
+gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
+ GLint teeth, GLfloat tooth_depth)
+{
+ GLint i;
+ GLfloat r0, r1, r2;
+ GLfloat angle, da;
+ GLfloat u, v, len;
+
+ 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;
+
+ glShadeModel(GL_FLAT);
+
+ glNormal3f(0.0, 0.0, 1.0);
+
+ /* draw front face */
+ glBegin(GL_QUAD_STRIP);
+ for (i = 0; i <= teeth; i++) {
+ angle = i * 2.0 * M_PI / teeth;
+ glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
+ glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
+ if (i < teeth) {
+ glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
+ glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
+ }
+ }
+ glEnd();
+
+ /* draw front sides of teeth */
+ glBegin(GL_QUADS);
+ da = 2.0 * M_PI / teeth / 4.0;
+ for (i = 0; i < teeth; i++) {
+ angle = i * 2.0 * M_PI / teeth;
+
+ glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
+ glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
+ glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
+ glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
+ }
+ glEnd();
+
+ glNormal3f(0.0, 0.0, -1.0);
+
+ /* draw back face */
+ glBegin(GL_QUAD_STRIP);
+ for (i = 0; i <= teeth; i++) {
+ angle = i * 2.0 * M_PI / teeth;
+ glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
+ glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
+ if (i < teeth) {
+ glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
+ glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
+ }
+ }
+ glEnd();
+
+ /* draw back sides of teeth */
+ glBegin(GL_QUADS);
+ da = 2.0 * M_PI / teeth / 4.0;
+ for (i = 0; i < teeth; i++) {
+ angle = i * 2.0 * M_PI / teeth;
+
+ glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
+ glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
+ glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
+ glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
+ }
+ glEnd();
+
+ /* draw outward faces of teeth */
+ glBegin(GL_QUAD_STRIP);
+ for (i = 0; i < teeth; i++) {
+ angle = i * 2.0 * M_PI / teeth;
+
+ glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
+ glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
+ u = r2 * cos(angle + da) - r1 * cos(angle);
+ v = r2 * sin(angle + da) - r1 * sin(angle);
+ len = sqrt(u * u + v * v);
+ u /= len;
+ v /= len;
+ glNormal3f(v, -u, 0.0);
+ glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
+ glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
+ glNormal3f(cos(angle), sin(angle), 0.0);
+ glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
+ glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
+ u = r1 * cos(angle + 3 * da) - r2 * cos(angle + 2 * da);
+ v = r1 * sin(angle + 3 * da) - r2 * sin(angle + 2 * da);
+ glNormal3f(v, -u, 0.0);
+ glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
+ glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
+ glNormal3f(cos(angle), sin(angle), 0.0);
+ }
+
+ glVertex3f(r1 * cos(0), r1 * sin(0), width * 0.5);
+ glVertex3f(r1 * cos(0), r1 * sin(0), -width * 0.5);
+
+ glEnd();
+
+ glShadeModel(GL_SMOOTH);
+
+ /* draw inside radius cylinder */
+ glBegin(GL_QUAD_STRIP);
+ for (i = 0; i <= teeth; i++) {
+ angle = i * 2.0 * M_PI / teeth;
+ glNormal3f(-cos(angle), -sin(angle), 0.0);
+ glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
+ glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
+ }
+ glEnd();
+
+}
+
+static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
+static GLint gear1, gear2, gear3;
+static GLfloat angle = 0.0;
+
+static void
+draw(void)
+{
+ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+ glPushMatrix();
+ 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);
+ glCallList(gear1);
+ glPopMatrix();
+
+ glPushMatrix();
+ glTranslatef(3.1, -2.0, 0.0);
+ glRotatef(-2.0 * angle - 9.0, 0.0, 0.0, 1.0);
+ glCallList(gear2);
+ glPopMatrix();
+
+ glPushMatrix();
+ glTranslatef(-3.1, 4.2, 0.0);
+ glRotatef(-2.0 * angle - 25.0, 0.0, 0.0, 1.0);
+ glCallList(gear3);
+ glPopMatrix();
+
+ glPopMatrix();
+
+ glutSwapBuffers();
+
+ Frames++;
+ {
+ GLint t = glutGet(GLUT_ELAPSED_TIME);
+ if (t - T0 >= 5000) {
+ GLfloat seconds = (t - T0) / 1000.0;
+ GLfloat fps = Frames / seconds;
+ printf("%d frames in %g seconds = %g FPS\n", Frames, seconds, fps);
+ T0 = t;
+ Frames = 0;
+ }
+ }
+}
+
+
+static void
+idle(void)
+{
+ angle += 2.0;
+ glutPostRedisplay();
+}
+
+/* change view angle, exit upon ESC */
+/* ARGSUSED1 */
+static void
+key(unsigned char k, int x, int y)
+{
+ switch (k) {
+ case 'z':
+ view_rotz += 5.0;
+ break;
+ case 'Z':
+ view_rotz -= 5.0;
+ break;
+ case 27: /* Escape */
+ exit(0);
+ break;
+ default:
+ return;
+ }
+ glutPostRedisplay();
+}
+
+/* change view angle */
+/* ARGSUSED1 */
+static void
+special(int k, int x, int y)
+{
+ switch (k) {
+ case GLUT_KEY_UP:
+ view_rotx += 5.0;
+ break;
+ case GLUT_KEY_DOWN:
+ view_rotx -= 5.0;
+ break;
+ case GLUT_KEY_LEFT:
+ view_roty += 5.0;
+ break;
+ case GLUT_KEY_RIGHT:
+ view_roty -= 5.0;
+ break;
+ default:
+ return;
+ }
+ glutPostRedisplay();
+}
+
+/* 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();
+ glFrustum(-1.0, 1.0, -h, h, 5.0, 60.0);
+ glMatrixMode(GL_MODELVIEW);
+ glLoadIdentity();
+ glTranslatef(0.0, 0.0, -40.0);
+}
+
+static void
+init(void)
+{
+ 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 = glGenLists(1);
+ glNewList(gear1, GL_COMPILE);
+ glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
+ gear(1.0, 4.0, 1.0, 20, 0.7);
+ glEndList();
+
+ gear2 = glGenLists(1);
+ glNewList(gear2, GL_COMPILE);
+ glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
+ gear(0.5, 2.0, 2.0, 10, 0.7);
+ glEndList();
+
+ gear3 = glGenLists(1);
+ glNewList(gear3, GL_COMPILE);
+ glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
+ gear(1.3, 2.0, 0.5, 10, 0.7);
+ glEndList();
+
+ glEnable(GL_NORMALIZE);
+}
+
+void
+visible(int vis)
+{
+ if (vis == GLUT_VISIBLE)
+ glutIdleFunc(idle);
+ else
+ glutIdleFunc(NULL);
+}
+
+int main(int argc, char *argv[])
+{
+ glutInit(&argc, argv);
+ glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
+
+ glutInitWindowPosition(0, 0);
+ glutInitWindowSize(300, 300);
+ glutCreateWindow("Gears");
+ init();
+
+ glutDisplayFunc(draw);
+ glutReshapeFunc(reshape);
+ glutKeyboardFunc(key);
+ glutSpecialFunc(special);
+ glutVisibilityFunc(visible);
+
+ glutMainLoop();
+ return 0; /* ANSI C requires main to return int. */
+}
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