mixing forward and deferred rendering

Question

Simplified version of my deferred rendering looks like this:

• bind fbo1
• clear color and depth buffers
• gbuffer stage (gbuffer contains only these pixels which pass a depth test)

• unbind fbo1

• bind fbo2

• clear color buffer
• draw a full screen quad, shading stage (render to the texture for some post processing effects)

• unbind fbo2

• clear color and depth buffers

• draw a full screen quad and render to the default framebuffer

How to combine that with the forward rendering ?

Answer 1

Copy the depth information to the la-buffer and then render normally to the la-buffer using forward shading. All you need to do to copy over the depth information is add this to the light accumulation fragment shader:

gl_FragDepth = texture(depthBuffer, texCoord).r;