Add support for an Atlas allocator for shadow maps #8345
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- when inserting an entry at a root other than zero, we need to update the children count of the root's parent. - the QuadTree array nodes need to be able to encode enough indices for the largest "layer" in the tree. With 7 layers the largest one has 4096 entries, so we need 12 bits, not 8.
We add an offset to the shadowmap viewport, but in this change it is always set to (0,0)
This feature is controled by a feature flag and is turned off at this point. This CL shouldn't change the existing behavior of shadowmap allocation as long as the atlas feature is not enanled. When enabled, shadowmap allocations are not limited to layers of the shadowmap texture, instead, an atlas is used meaning a layer can be shared by multiple shadowmaps. At the very least this can save a lot of memory as smaller shadowmaps can be packed together. Currently this feature breaks some VSM features: - mipmapping - blurring
poweifeng
approved these changes
Jan 13, 2025
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This feature is controled by a feature flag and is turned off at this point.
This CL shouldn't change the existing behavior of shadowmap allocation as
long as the atlas feature is not enanled.
When enabled, shadowmap allocations are not limited to layers of the
shadowmap texture, instead, an atlas is used meaning a layer can
be shared by multiple shadowmaps. At the very least this can save
a lot of memory as smaller shadowmaps can be packed together.
Currently this feature breaks some VSM features: