Note that moving to the templated versions of array allocation functions
in [0] caused integer overflow regressions because multiplying by the
`sizeof(type)` caused the following values to be cast to a size_t.
[0]: e85ebb24fe
All 2D vectors related to image transform code were changed to float2.
Previously, it was decided, that 4x4 matrix should be used for 2D
affine transform, but this is changed to 3x3 now.
Texture painting code did rely on `IMB_transform` with 4x4 matrix.
To avoid large changes, I have added function
`BLI_rctf_transform_calc_m3_pivot_min`.
Main motivation is cleaner code - ease of use of c++ API, and avoiding
returning values by arguments.
Pull Request: https://projects.blender.org/blender/blender/pulls/133692
API: merged IMB_scalefastImBuf, IMB_scaleImBuf, IMB_scaleImBuf_threaded
into one function IMB_scale with enum IMBScaleFilter {Nearest, Bilinear, Box}
and bool "threaded" param.
Performance:
- Box filtering (nee IMB_scaleImBuf) can be multi-threaded now.
- Nearest filtering (nee IMB_scalefastImBuf) can be multi-threaded now.
Also fix performance regression on float images caused by fix in #126234
- Bilinear filtering (nee IMB_scaleImBuf_threaded) is several times faster now.
Correctness:
- Nearest and Box filtering: no longer loses half of edge pixels when scaling
up.
- Box: fixed garbage results (and possible out of bounds reads) for non-4
channel float images.
- Bilinear: no longer shifts image when scaling up.
- Bilinear: properly filters when scaling down by 2x2.
Test coverage:
- Add gtest coverage for various IMB_scale modes.
- Add a IMB_performance_test performance test, ran manually.
More details, images and performance numbers in PR.
Pull Request: https://projects.blender.org/blender/blender/pulls/126390
