// draw inside radius cylinder
lastDrawIndex += gear.addDrawCommand(GL_TRIANGLE_STRIP, lastDrawIndex, (teeth + 1) * 2);
for ( i = 0; i <= teeth; i++ ) {
angle = i * 2.0f * (float)Math.PI / teeth;
imb.glNormal3f(-cos(angle), -sin(angle), 0.0f);
imb.glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5f);
imb.glNormal3f(-cos(angle), -sin(angle), 0.0f);
imb.glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5f);
}