Blending

Enable blending		`glEnable(GL_BLEND)`

Set the blending function		`glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)`

Assign alpha < 1		`glColor4f(1, 0, 0, 0.5)` or `glMaterialfv(GL_FRONT, GL_DIFFUSE, [1, 0, 0, 0.5])`