actions/itgmania212121
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

when dithering, round the alpha channel instead of truncating

Browse Source
This commit is contained in:
Glenn Maynard
2004-05-02 03:41:33 +00:00
parent 58d63cb476
commit ac81016af4
1 changed files with 14 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files
stepmania/src/SDL_dither.cpp
+14 -2
View File
@@ -125,7 +125,13 @@ void SM_SDL_OrderedDither(const SDL_Surface *src, SDL_Surface *dst)
int out_intensity = colors[3] * conv[3]; int out_intensity = colors[3] * conv[3];
/* Truncate, and add e to make sure a value of 14.999998 -> 15. */ /* Truncate, and add e to make sure a value of 14.999998 -> 15. */
colors[3] = Uint8((out_intensity + 1) >> 16); // colors[3] = Uint8((out_intensity + 1) >> 16);
/* I don't remember why this used to truncate. Doing that causes
* dithering to an image with 1-bit alpha to be transparent on all
* source alpha values except for full-opaque, which is wrong.
* Add .5, so we round. */
colors[3] = Uint8((out_intensity + 32767) >> 16);
} }
/* Raw value -> int -> pixel */ /* Raw value -> int -> pixel */
@@ -249,7 +255,13 @@ void SM_SDL_ErrorDiffusionDither(const SDL_Surface *src, SDL_Surface *dst)
int out_intensity = colors[3] * conv[3]; int out_intensity = colors[3] * conv[3];
/* Truncate, and add e to make sure a value of 14.999998 -> 15. */ /* Truncate, and add e to make sure a value of 14.999998 -> 15. */
colors[3] = Uint8((out_intensity + 1) >> 16); // colors[3] = Uint8((out_intensity + 1) >> 16);
/* I don't remember why this used to truncate. Doing that causes
* dithering to an image with 1-bit alpha to be transparent on all
* source alpha values except for full-opaque, which is wrong.
* Add .5, so we round. */
colors[3] = Uint8((out_intensity + 32767) >> 16);
} }
mySDL_SetRawRGBAV( dstp, dst, colors ); mySDL_SetRawRGBAV( dstp, dst, colors );