Add the gears from glxgears.
diff --git a/gears.c b/gears.c
new file mode 100644
index 0000000..db79d4d
--- /dev/null
+++ b/gears.c
@@ -0,0 +1,207 @@
+#include <stdlib.h>
+#include <math.h>
+#include <GL/gl.h>
+#include "gears.h"
+
+struct gears {
+ GLint gear1, gear2, gear3;
+};
+
+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();
+}
+
+struct gears *
+gears_create(void)
+{
+ 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};
+ static GLfloat pos[4] = {5.0, 5.0, 10.0, 0.0};
+ struct gears *gears;
+
+ gears = malloc(sizeof *gears);
+ /* make the gears */
+ gears->gear1 = glGenLists(1);
+ glNewList(gears->gear1, GL_COMPILE);
+ glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
+ gear(1.0, 4.0, 1.0, 20, 0.7);
+ glEndList();
+
+ gears->gear2 = glGenLists(1);
+ glNewList(gears->gear2, GL_COMPILE);
+ glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
+ gear(0.5, 2.0, 2.0, 10, 0.7);
+ glEndList();
+
+ gears->gear3 = glGenLists(1);
+ glNewList(gears->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);
+
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 200.0);
+ glMatrixMode(GL_MODELVIEW);
+
+ glLightfv(GL_LIGHT0, GL_POSITION, pos);
+ glEnable(GL_CULL_FACE);
+ glEnable(GL_LIGHTING);
+ glEnable(GL_LIGHT0);
+ glEnable(GL_DEPTH_TEST);
+
+ return gears;
+}
+
+void
+gears_draw(struct gears *gears, GLfloat angle)
+{
+ GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
+
+ glPushMatrix();
+
+ glTranslatef(0.0, 0.0, -50);
+
+ 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(gears->gear1);
+ glPopMatrix();
+
+ glPushMatrix();
+ glTranslatef(3.1, -2.0, 0.0);
+ glRotatef(-2.0 * angle - 9.0, 0.0, 0.0, 1.0);
+ glCallList(gears->gear2);
+ glPopMatrix();
+
+
+ glPushMatrix();
+ glTranslatef(-3.1, 4.2, 0.0);
+ glRotatef(-2.0 * angle - 25.0, 0.0, 0.0, 1.0);
+ glCallList(gears->gear3);
+ glPopMatrix();
+
+ glPopMatrix();
+
+ glFlush();
+}