Add XMMatrixInverseTranspose for optimal normal vector transformation - #336
Open
RohithPariki wants to merge 1 commit into
Open
Add XMMatrixInverseTranspose for optimal normal vector transformation#336RohithPariki wants to merge 1 commit into
RohithPariki wants to merge 1 commit into
Conversation
|
Azure Pipelines: There may be pipelines that require an authorized user to comment /azp run to run. |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Fixes #9
Description
This PR introduces
XMMatrixInverseTranspose, computing(M^-1)^Tin a single pass. This is a common operation used for transforming surface normals, where developers previously had to chainXMMatrixTranspose(XMMatrixInverse(nullptr, M)).Optimization Insight:
The standard
XMMatrixInverseinternally transposes the matrix first (MT = M^T) and then computes the cofactors ofMTto produceadj(M^T) = adj(M)^T. Since the caller ultimately requests the transpose of the inverse, that final transpose cancels out the internal one.XMMatrixInverseTransposesimply runs the cofactor algorithm directly onM(skipping the initial transpose block entirely) to produceadj(M) / det(M).Savings:
_mm_shuffle_psinstructions on the_XM_SSE_INTRINSICS_path.Verification
All paths (Scalar, NEON, and SSE) were successfully implemented and verified against chained calls (
Transpose(Inverse(M))) for:(invT(R) == R)i can share the test code , if needed.