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
Download patch file Download diff file Expand all files Collapse all files

27
src/render/direct3d/SDL_render_d3d.c
View file

@ -227,6 +227,7 @@ typedef struct
D3DPRESENT_PARAMETERS pparams;
SDL_bool updateSize;
SDL_bool beginScene;
SDL_bool enableSeparateAlphaBlend;
D3DTEXTUREFILTERTYPE scaleMode;
IDirect3DSurface9 *defaultRenderTarget;
IDirect3DSurface9 *currentRenderTarget;
@ -615,6 +616,10 @@ D3D_CreateRenderer(SDL_Window * window, Uint32 flags)
renderer->info.flags |= SDL_RENDERER_TARGETTEXTURE;
}
if (caps.PrimitiveMiscCaps & D3DPMISCCAPS_SEPARATEALPHABLEND) {
data->enableSeparateAlphaBlend = SDL_TRUE;
}
/* Set up parameters for rendering */
IDirect3DDevice9_SetVertexShader(data->device, NULL);
IDirect3DDevice9_SetFVF(data->device,
@ -637,6 +642,10 @@ D3D_CreateRenderer(SDL_Window * window, Uint32 flags)
D3DTA_TEXTURE);
IDirect3DDevice9_SetTextureStageState(data->device, 0, D3DTSS_ALPHAARG2,
D3DTA_DIFFUSE);
/* Enable separate alpha blend function, if possible */
if (data->enableSeparateAlphaBlend) {
IDirect3DDevice9_SetRenderState(data->device, D3DRS_SEPARATEALPHABLENDENABLE, TRUE);
}
/* Disable second texture stage, since we're done */
IDirect3DDevice9_SetTextureStageState(data->device, 1, D3DTSS_COLOROP,
D3DTOP_DISABLE);
@ -979,6 +988,12 @@ D3D_SetBlendMode(D3D_RenderData * data, int blendMode)
D3DBLEND_SRCALPHA);
IDirect3DDevice9_SetRenderState(data->device, D3DRS_DESTBLEND,
D3DBLEND_INVSRCALPHA);
if (data->enableSeparateAlphaBlend) {
IDirect3DDevice9_SetRenderState(data->device, D3DRS_SRCBLENDALPHA,
D3DBLEND_ONE);
IDirect3DDevice9_SetRenderState(data->device, D3DRS_DESTBLENDALPHA,
D3DBLEND_INVSRCALPHA);
}
break;
case SDL_BLENDMODE_ADD:
IDirect3DDevice9_SetRenderState(data->device, D3DRS_ALPHABLENDENABLE,
@ -987,6 +1002,12 @@ D3D_SetBlendMode(D3D_RenderData * data, int blendMode)
D3DBLEND_SRCALPHA);
IDirect3DDevice9_SetRenderState(data->device, D3DRS_DESTBLEND,
D3DBLEND_ONE);
if (data->enableSeparateAlphaBlend) {
IDirect3DDevice9_SetRenderState(data->device, D3DRS_SRCBLENDALPHA,
D3DBLEND_ZERO);
IDirect3DDevice9_SetRenderState(data->device, D3DRS_DESTBLENDALPHA,
D3DBLEND_ONE);
}
break;
case SDL_BLENDMODE_MOD:
IDirect3DDevice9_SetRenderState(data->device, D3DRS_ALPHABLENDENABLE,
@ -995,6 +1016,12 @@ D3D_SetBlendMode(D3D_RenderData * data, int blendMode)
D3DBLEND_ZERO);
IDirect3DDevice9_SetRenderState(data->device, D3DRS_DESTBLEND,
D3DBLEND_SRCCOLOR);
if (data->enableSeparateAlphaBlend) {
IDirect3DDevice9_SetRenderState(data->device, D3DRS_SRCBLENDALPHA,
D3DBLEND_ZERO);
IDirect3DDevice9_SetRenderState(data->device, D3DRS_DESTBLENDALPHA,
D3DBLEND_ONE);
}
break;
}
}