// When a pixel is at far plane, the world space coordinate reconstruction is not reliable.
// So in order to have a valid position (for example for height fog) we just consider that the sky is a sphere centered on camera with a radius of 5km (arbitrarily chosen value!)
// And recompute the position on the sphere with the current camera direction.
// When a pixel is at far plane, the world space coordinate reconstruction is not reliable.
// So in order to have a valid position (for example for height fog) we just consider that the sky is a sphere centered on camera with a radius of 5km (arbitrarily chosen value!)
// And recompute the position on the sphere with the current camera direction.