Fix RGB channel swap in STBICodec RGB-to-RGBA conversion (v2-3)#567
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taylorhoward92 wants to merge 1 commit intoOGRECave:v2-3from
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Fix RGB channel swap in STBICodec RGB-to-RGBA conversion (v2-3)#567taylorhoward92 wants to merge 1 commit intoOGRECave:v2-3from
taylorhoward92 wants to merge 1 commit intoOGRECave:v2-3from
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stb_image always returns pixel data in RGB byte order, but the variable names in the 3-component conversion loop (b, g, r) assume BGR order. The code then writes r, g, b — which actually outputs B, G, R — into a buffer declared as PFG_RGBA8_UNORM (R first), swapping the red and blue channels. Fix by writing b, g, r (preserving stb's native RGB order), which matches the correct behaviour already present on master (v3-0). The visual effect of this bug is that all 3-channel RGB textures rendered through the STB codec have red and blue swapped (e.g. brown skin appears blue, lime-green appears teal). See the screenshots in osrf/homebrew-simulation#3394 (comment 4101535199) for an example. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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@taylorhoward92 I quickly tested your patch and it fixes the color swap problem in |
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Apr 9, 2026
Adds patch from OGRECave/ogre-next#567 to fix RGB→RGBA channel swap in STBICodec. Updates hash for PR 566 patch. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Adds patch from OGRECave/ogre-next#567 to fix RGB→RGBA channel swap in STBICodec. Updates hash for PR 566 patch. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Tested via Gazebo. Without the fix: With the fix: |
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it looks like the fix in 3.0.0 was made in #317 as part of a larger change |
scpeters
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Apr 9, 2026
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Summary
b, g, rassume BGR input, butstb_imagealways returns RGBr, g, b(actually B, G, R) intoPFG_RGBA8_UNORM(R-first) swaps red and blueb, g, rwrite order — this backports the fix to v2-3Visual evidence
See the screenshots in osrf/homebrew-simulation#3394 (comment) — the "Rescue Randy" model has blue skin and teal jacket instead of brown skin and lime jacket when ogre 2.3 is built without FreeImage (STB codec active).
Test plan
OGRE_CONFIG_ENABLE_FREEIMAGE=OFF,OGRE_CONFIG_ENABLE_STBI=ON)fuel_textured_mesh.sdfin gz-sim)