Reusing MRTs for mobile GPUs

Recent mobile GPUs support OpenGL ES 3.x for high quality graphics contents. Multiple render targets (MRTs) are one of the new important features of the OpenGL ES 3.x specification. MRTs facilitate rendering multiple render-target textures (called G-buffer) at once, so this feature enables deferred shading; after various geometry data, such as color, normal, reflection, and refraction, are rendered into the G-buffer in the first pass, we can perform screen-space lighting using the G-buffer data in the second pass. Complex lighting with deferred shading is now very common on desktop and console devices.