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| author | Marcus Comstedt | 2014-01-10 15:45:37 +0100 |
|---|---|---|
| committer | Marcus Comstedt | 2014-01-10 15:56:53 +0100 |
| commit | 51d7405a7b741b8028b83e1548b3b8260230c5a1 (patch) | |
| tree | a2509ec12e29a54b9e47ceb91d12206583e96894 | |
| parent | 66ad9e76eeda77f2ca4d10db82cfd31dba38d127 (diff) | |
| download | scummvm-rg350-51d7405a7b741b8028b83e1548b3b8260230c5a1.tar.gz scummvm-rg350-51d7405a7b741b8028b83e1548b3b8260230c5a1.tar.bz2 scummvm-rg350-51d7405a7b741b8028b83e1548b3b8260230c5a1.zip | |
GRAPHICS: Fix computation of addA in darkenFill()
The old computation had rounding issues, causing alpha to leak into
the red (usually) component. There's a much easier way to compute it
that does not lead to such problems: What should really happen is that
the two top bits of the A component should be set to 1 (thus adding
75% alpha). So compute it that way for speed and precision.
| -rw-r--r-- | graphics/VectorRendererSpec.cpp | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/graphics/VectorRendererSpec.cpp b/graphics/VectorRendererSpec.cpp index ce04db8a67..de249e8711 100644 --- a/graphics/VectorRendererSpec.cpp +++ b/graphics/VectorRendererSpec.cpp @@ -691,8 +691,7 @@ darkenFill(PixelType *ptr, PixelType *end) { // assuming at least 3 alpha bits mask |= 3 << _format.aShift; - PixelType addA = (PixelType)(255 >> _format.aLoss) << _format.aShift; - addA -= (addA >> 2); + PixelType addA = (PixelType)(3 << (_format.aShift + 6 - _format.aLoss)); while (ptr != end) { // Darken the colour, and increase the alpha |