Implementation - transparency in OpenGL

General Process:

- 1. Draw all non-transparent objects
- 2.a Activate color blending, desactivate depth buffer write
- 2.b Sort transparent objects by depth to the camera

- \(p_{proj} = Proj \times ModelView \times p\)
- \(z_{depth} = p_{proj}.z/p_{proj}.w\)

- 3. Draw transparent objects from furthest to closest

 ... Draw all non-transparent objects ...
glEnable(GL_BLEND); // Color Blending
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glDepthMask(false); // do not write on depth buffer
 ... Sort transparent objects by depth ...
 ... Draw all transparent objects from furthest to closest ...
glDisable(GL_BLEND); 
// do not forget to re-activate depth buffer write
glDepthMask(true);