glDepthRangeIndexed

GlDepthRangeIndexed is a function in the OpenGL API that allows for the specification of different depth ranges for each index of a texture array. It is used to set the near and far clipping planes for the depth buffer, which controls how objects are rendered in the scene.

The function takes two parameters: the index of the texture array and a normalised vector that defines the near and far clipping planes. The near plane is the first value in the vector, and the far plane is the second value. The function sets the depth range for the specified index to the range defined by this vector.

When calling glDepthRangeIndexed, the values in the vector must be in Normalized Device Coordinate (NDC) space, which ranges from -1.0 to 1.0. Attempting to set the depth range outside of this range will result in a No error but the actual value might not cause any issues or be broken at least not that you would notice.

This function is typically used in fragment shaders to create custom depth ranges for a texture array. For example, it might be used to create a parallax-like effect, where the near plane is set close to the viewer, while the far plane is set far away, resulting in a depth range that is only visible up close.

In the fixed-function pipeline, it is not possible to use glDepthRangeIndexed directly, as the fixed pipeline uses its own hardcoded depth range that cannot be altered directly by the application. However, this can still be achieved indirectly by using shaders in the programmable pipeline, allowing for more advanced rendering techniques.