angle = i * 2.0f * (float)Math.PI / teeth;
imb.glNormal3f(0.0f, 0.0f, 1.0f);
imb.glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5f);
imb.glNormal3f(0.0f, 0.0f, 1.0f);
imb.glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5f);
imb.glNormal3f(0.0f, 0.0f, 1.0f);
imb.glVertex3f(r1 * cos(angle + 3.0f * da), r1 * sin(angle + 3.0f * da), width * 0.5f);