Weizhen Huang
9fe87646d5
The spotlight is now treated as a sphere instead of a view-aligned disk. The implementation remains almost identical to that of a point light, except for the spotlight attenuation and spot blend. There is no attenuation inside the sphere. Ref #108505 Other changes include: ## Sampling Instead of sampling the disk area, the new implementation samples either the cone of the visible portion on the sphere or the spread cone, based on which cone has a smaller solid angle. This reduces noise when the spotlight has a large radius and a small spread angle. | Before | After | | -- | -- | || ## Texture Spot light can now project texture using UV coordinates. <video src="/attachments/6db989d2-7a3c-4b41-9340-f5690d48c4fb" title="spot_light_texture.mp4" controls></video> ## Normalization Previously, the normalization factor for the spotlight was \(\pi r^2\), the area of a disk. This factor has been adjusted to \(4\pi r^2\) to account for the surface area of a sphere. This change also affects point light since they share the same kernel type. ## Versioning Some pipeline uses the `Normal` socket of the Texture Coordinate node for projection, because `ls->Ng` was set to the incoming direction at the current shading point. Now that `ls->Ng` corresponds to the normal direction of a point on the sphere (except when the radius is zero), we replace these nodes with a combination of the Geometry shader node and the Vector Transform node, which gives the same result as before.  Example file see https://archive.blender.org/developer/T93676 Pull Request: https://projects.blender.org/blender/blender/pulls/109329
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