What is buffer shader?
A Shader Storage Buffer Object is a Buffer Object that is used to store and retrieve data from within the OpenGL Shading Language. SSBOs are a lot like Uniform Buffer Objects. Shader storage blocks are defined by Interface Block (GLSL)s in almost the same way as uniform blocks.
How a buffer is better than Z buffer?
Z buffer and A buffer are two of the most popular visible surface detection techniques. In fact, A buffer is an extension to Z buffer, which adds anti-aliasing. Typically, A buffer has a better image resolution than Z buffer, because it uses an easily computable Fourier window.
How to access the depth buffer from a fragment shader?
In the fragment shader, this quad samples the depth buffer at that location and changes its color/alpha in order to make that pixel as foggy as needs be. Now I know I can render the scene with the depth buffer linked to a texture, render the scene normally and then render the fog, passing it that texture, but this is one rendering too many.
Can you read and write to the depth buffer?
Unless you render in multiple passes, you cannot read and write to the depth buffer in a fragment shader. That is to say, you cannot use a depth texture to read the depth and then turn around and write a new depth.
How to access depth buffer values in OpenGL?
Technically there are some hardware optimizations that will write/test the depth early, but for all intents and purposes gl_FragCoord.z is not the value stored in the depth buffer. Unless you render in multiple passes, you cannot read and write to the depth buffer in a fragment shader.
What is the z component of a fragment shader?
The z component is the depth value that would be used for the fragment’s depth if no shader contained any writes to gl_FragDepth. This is useful for invariance if a shader conditionally computes gl_FragDepth but otherwise wants the fixed functionality fragment depth.