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fix scaling glitch that could cause images to be slightly transparent

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when blitting bit depth up
This commit is contained in:
Glenn Maynard
2004-09-26 08:22:46 +00:00
parent f30127bcab
commit cc55c46033
1 changed files with 22 additions and 3 deletions
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stepmania/src/RageSurfaceUtils.cpp
+22 -3
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@@ -553,10 +553,29 @@ static bool blit_rgba_to_rgba( const RageSurface *src_surf, const RageSurface *d
* lrintf( ((float) i / max_src_val) * max_dst_val ) * lrintf( ((float) i / max_src_val) * max_dst_val )
* { 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3 } * { 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3 }
* *
* We use the first, since it gives the most even distribution. * We use the first for increasing resolution, since it gives the most even
* distribution.
*
* 2->4 bit:
* SCALE( i, 0, max_src_val+1, 0, max_dst_val+1 );
* { 0, 4, 8, 12 }
* SCALE( i, 0, max_src_val, 0, max_dst_val );
* { 0, 5, 10, 15 }
* lrintf( ((float) i / max_src_val) * max_dst_val )
* { 0, 5, 10, 15 }
*
* The latter two are equivalent and give an even distribution; we use the
* second, since the first doesn't scale max_src_val to max_dst_val.
*
* Having separate formulas for increasing and decreasing resolution seems
* strange; what's wrong here?
*/ */
for( uint32_t i = 0; i <= max_src_val; ++i ) if( max_src_val > max_dst_val )
lookup[c][i] = (uint8_t) SCALE( i, 0, max_src_val+1, 0, max_dst_val+1 ); for( uint32_t i = 0; i <= max_src_val; ++i )
lookup[c][i] = (uint8_t) SCALE( i, 0, max_src_val+1, 0, max_dst_val+1 );
else
for( uint32_t i = 0; i <= max_src_val; ++i )
lookup[c][i] = (uint8_t) SCALE( i, 0, max_src_val, 0, max_dst_val );
} }
} }