Add a Dynamic BVH implementation. #44531
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reduz
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| DynamicBVH::Node *DynamicBVH::_node_sort(Node *n, Node *&r) { | ||
| Node *p = n->parent; | ||
| ERR_FAIL_COND_V(!n->is_internal(), nullptr); | ||
| if (p > n) { |
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Is this meant to compare the pointers or are we missing a comparison operator?
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Good catch, it appears to be like this on Bullet too, it does not make much sense to me, I wonder why is this done this way..
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bullet also allocates on heap, so I should assume it has some sort of meaning, but i really really cant figure it out.
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yup, I would expect the comparison to have some sort of geometric meaning...
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My wild guess is that it may be to avoid a redundant rotation or something like this, but the code is too cryptic. Maybe @lawnjelly knows?
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Maybe it's a variation of !=. It doesn't make much sense.
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Could it be related to cache efficiency? With this sorting the nodes closer to the root of the tree will end up closer in memory, and depending on the allocator they could even be in contiguous memory.
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It looks like this is just sorting nodes by memory address for cache optimization. It swaps parent and child completely, including their volumes so I don't think it has a geometric reason.
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Ah, I had missed the latest comment. I agree with this interpretation :)
-Based on Bullet Dbvh, has style and functional changes. -Provides efficient pairing -Needed to optimize rendering -Needed to optimize physics This PR is up for others to review the implementation.
reduz
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I think that this PR should also contains tests, because seems that results will be mostly reproducible and this will prevent from regressions like in LocalVector - #40913 |
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@qarmin I agree, though its difficult to think how tests for this could be created |
-Based on Bullet Dbvh, has style and functional changes.
-Helps achieve efficient pairing
-Needed to optimize rendering
-Needed to optimize physics