/**
* 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.
*
* @param inner_radius radius of hole at center
* @param outer_radius radius at center of teeth
* @param width width of gear
* @param teeth number of teeth
* @param tooth_depth depth of tooth
*/
private static void gear(
float inner_radius, float outer_radius, float width, int teeth, float tooth_depth) {
int i;
float r0, r1, r2;
float angle, da;
float u, v, len;
r0 = inner_radius;
r1 = outer_radius - tooth_depth / 2.0f;
r2 = outer_radius + tooth_depth / 2.0f;
da = 2.0f * (float) Math.PI / teeth / 4.0f;
glShadeModel(GL_FLAT);
glNormal3f(0.0f, 0.0f, 1.0f);
/* draw front face */
glBegin(GL_QUAD_STRIP);
for (i = 0; i <= teeth; i++) {
angle = i * 2.0f * (float) Math.PI / teeth;
glVertex3f(r0 * (float) Math.cos(angle), r0 * (float) Math.sin(angle), width * 0.5f);
glVertex3f(r1 * (float) Math.cos(angle), r1 * (float) Math.sin(angle), width * 0.5f);
if (i < teeth) {
glVertex3f(r0 * (float) Math.cos(angle), r0 * (float) Math.sin(angle), width * 0.5f);
glVertex3f(
r1 * (float) Math.cos(angle + 3.0f * da),
r1 * (float) Math.sin(angle + 3.0f * da),
width * 0.5f);
}
}
glEnd();
/* draw front sides of teeth */
glBegin(GL_QUADS);
for (i = 0; i < teeth; i++) {
angle = i * 2.0f * (float) Math.PI / teeth;
glVertex3f(r1 * (float) Math.cos(angle), r1 * (float) Math.sin(angle), width * 0.5f);
glVertex3f(
r2 * (float) Math.cos(angle + da), r2 * (float) Math.sin(angle + da), width * 0.5f);
glVertex3f(
r2 * (float) Math.cos(angle + 2.0f * da),
r2 * (float) Math.sin(angle + 2.0f * da),
width * 0.5f);
glVertex3f(
r1 * (float) Math.cos(angle + 3.0f * da),
r1 * (float) Math.sin(angle + 3.0f * da),
width * 0.5f);
}
glEnd();
/* draw back face */
glBegin(GL_QUAD_STRIP);
for (i = 0; i <= teeth; i++) {
angle = i * 2.0f * (float) Math.PI / teeth;
glVertex3f(r1 * (float) Math.cos(angle), r1 * (float) Math.sin(angle), -width * 0.5f);
glVertex3f(r0 * (float) Math.cos(angle), r0 * (float) Math.sin(angle), -width * 0.5f);
glVertex3f(
r1 * (float) Math.cos(angle + 3 * da),
r1 * (float) Math.sin(angle + 3 * da),
-width * 0.5f);
glVertex3f(r0 * (float) Math.cos(angle), r0 * (float) Math.sin(angle), -width * 0.5f);
}
glEnd();
/* draw back sides of teeth */
glBegin(GL_QUADS);
for (i = 0; i < teeth; i++) {
angle = i * 2.0f * (float) Math.PI / teeth;
glVertex3f(
r1 * (float) Math.cos(angle + 3 * da),
r1 * (float) Math.sin(angle + 3 * da),
-width * 0.5f);
glVertex3f(
r2 * (float) Math.cos(angle + 2 * da),
r2 * (float) Math.sin(angle + 2 * da),
-width * 0.5f);
glVertex3f(
r2 * (float) Math.cos(angle + da), r2 * (float) Math.sin(angle + da), -width * 0.5f);
glVertex3f(r1 * (float) Math.cos(angle), r1 * (float) Math.sin(angle), -width * 0.5f);
}
glEnd();
/* draw outward faces of teeth */
glBegin(GL_QUAD_STRIP);
for (i = 0; i < teeth; i++) {
angle = i * 2.0f * (float) Math.PI / teeth;
glVertex3f(r1 * (float) Math.cos(angle), r1 * (float) Math.sin(angle), width * 0.5f);
glVertex3f(r1 * (float) Math.cos(angle), r1 * (float) Math.sin(angle), -width * 0.5f);
u = r2 * (float) Math.cos(angle + da) - r1 * (float) Math.cos(angle);
v = r2 * (float) Math.sin(angle + da) - r1 * (float) Math.sin(angle);
len = (float) Math.sqrt(u * u + v * v);
u /= len;
v /= len;
glNormal3f(v, -u, 0.0f);
glVertex3f(
r2 * (float) Math.cos(angle + da), r2 * (float) Math.sin(angle + da), width * 0.5f);
glVertex3f(
r2 * (float) Math.cos(angle + da), r2 * (float) Math.sin(angle + da), -width * 0.5f);
glNormal3f((float) Math.cos(angle), (float) Math.sin(angle), 0.0f);
glVertex3f(
r2 * (float) Math.cos(angle + 2 * da),
r2 * (float) Math.sin(angle + 2 * da),
width * 0.5f);
glVertex3f(
r2 * (float) Math.cos(angle + 2 * da),
r2 * (float) Math.sin(angle + 2 * da),
-width * 0.5f);
u = r1 * (float) Math.cos(angle + 3 * da) - r2 * (float) Math.cos(angle + 2 * da);
v = r1 * (float) Math.sin(angle + 3 * da) - r2 * (float) Math.sin(angle + 2 * da);
glNormal3f(v, -u, 0.0f);
glVertex3f(
r1 * (float) Math.cos(angle + 3 * da),
r1 * (float) Math.sin(angle + 3 * da),
width * 0.5f);
glVertex3f(
r1 * (float) Math.cos(angle + 3 * da),
r1 * (float) Math.sin(angle + 3 * da),
-width * 0.5f);
glNormal3f((float) Math.cos(angle), (float) Math.sin(angle), 0.0f);
}
glVertex3f(r1 * (float) Math.cos(0), r1 * (float) Math.sin(0), width * 0.5f);
glVertex3f(r1 * (float) Math.cos(0), r1 * (float) Math.sin(0), -width * 0.5f);
glEnd();
glShadeModel(GL_SMOOTH);
/* draw inside radius cylinder */
glBegin(GL_QUAD_STRIP);
for (i = 0; i <= teeth; i++) {
angle = i * 2.0f * (float) Math.PI / teeth;
glNormal3f(-(float) Math.cos(angle), -(float) Math.sin(angle), 0.0f);
glVertex3f(r0 * (float) Math.cos(angle), r0 * (float) Math.sin(angle), -width * 0.5f);
glVertex3f(r0 * (float) Math.cos(angle), r0 * (float) Math.sin(angle), width * 0.5f);
}
glEnd();
}
