Native bindings to the ARB_sample_shading extension.

In standard multisample rendering, an implementation is allowed to assign the same color and texture coordinate values to each sample, which then allows the optimization where the shader is only evaluated once and then distributed to the samples that have been determined to be covered by the primitive currently being rasterized. This can cause aliasing where the input color and texture coordinates are used to generate a result that doesn't antialias itself, for example with alpha-tested transparency.

This extension adds the ability to explicitly request that an implementation use a minimum number of unique set of fragment computation inputs when multisampling a pixel. Specifying such a requirement can reduce aliasing that results from evaluating the fragment computations too few times per pixel.

This extension adds new global state that controls the minimum number of samples for which attribute data is independently interpolated. When enabled, all operations that were traditionally executed per-fragment operate independently on each sample.

This also extends the shading language to allow control over the sample being processed. This includes built-in fragment input variables identifying the sample number and position being processed when executing fragment shaders per sample.

Requires OpenGL 2.0 and GLSL 1.30. Promoted to core in OpenGL 3.0.