pandory500/SDL-mirror
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Updated blend semantics so blending uses the following formula:

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dstRGB = (srcRGB * srcA) + (dstRGB * (1-srcA))
    dstA = srcA + (dstA * (1-srcA))
This allows proper compositing semantics without requiring premultiplied alpha.

Needs full unit test coverage and bug fixes!
This commit is contained in:
Sam Lantinga 2013-07-23 08:06:49 -07:00
parent a99edf3519
commit 32188834b5
17 changed files with 362 additions and 1001 deletions
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15
include/SDL_blendmode.h
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@ -39,10 +39,17 @@ extern "C" {
*/
typedef enum
{
SDL_BLENDMODE_NONE = 0x00000000, /**< No blending */
SDL_BLENDMODE_BLEND = 0x00000001, /**< dst = (src * A) + (dst * (1-A)) */
SDL_BLENDMODE_ADD = 0x00000002, /**< dst = (src * A) + dst */
SDL_BLENDMODE_MOD = 0x00000004 /**< dst = src * dst */
SDL_BLENDMODE_NONE = 0x00000000, /**< no blending
dstRGBA = srcRGBA */
SDL_BLENDMODE_BLEND = 0x00000001, /**< alpha blending
dstRGB = (srcRGB * srcA) + (dstRGB * (1-srcA))
dstA = srcA + (dstA * (1-srcA)) */
SDL_BLENDMODE_ADD = 0x00000002, /**< additive blending
dstRGB = (srcRGB * srcA) + dstRGB
dstA = dstA */
SDL_BLENDMODE_MOD = 0x00000004 /**< color modulate
dstRGB = srcRGB * dstRGB
dstA = dstA */
} SDL_BlendMode;
/* Ends C function definitions when using C++ */