How to make the transparent black in the surface become "transparent"?
When I use
HRESULT D3DXLoadSurfaceFromSurface(
LPDIRECT3DSURFACE9pDestSurface,
CONST PALETTEENTRY *pDestPalette,
CONST RECT *pDestRect,
LPDIRECT3DSURFACE9pSrcSurface,
CONST PALETTEENTRY *pSrcPalette,
CONST RECT *pSrcRect,
DWORDFilter,
D3DCOLORColorKey
);
according to the documantation of directx sdk, the color specified in ColorKey will be replaced by transparent black.
But if I load this surface to another surface, by D3DXLoadSurfaceFromSurface or StretchRect, the transparent black is visible and covering the background image in other surface.
So my question is, how to make the transparent black become "transparent" so that the image in other surface is not covered by that transparent black?
Thank you.
p.s. if I don't want to use sprite class, is there any solution?
[1079 byte] By [
waison] at [2007-12-23]
I had the same problem you have before and I did the following stuff to fix it, I wish they can help
you as well
d3dDevice->SetRenderState(D3DRS_ALPHABLENDENABLE,true);
d3dDevice->SetRenderState(D3DRS_SRCBLEND,D3DBLEND_SRCALPHA);
d3dDevice->SetRenderState(D3DRS_DESTBLEND,D3DBLEND_INVSRCALPHA);
this is where I found the solution:
http://www.mvps.org/directx/articles/colorkeydx8.htm
However I do have a question is that since the above article I found is about DirectX8, then why I have to
do this in Directx9 as well to make the transparency effect work?
I hope somebody passed by here could give me some clue......
When you load a texture without alpha channel the Alpha is FF by default, not 00
Because it's assumed that the color is not transparent alpha 00 but opaque so a Alpha of FF
So if your colorkey test value is 0,0,0,0 it's not going to compare to any black in your loaded Texture
Because all your black color in your texture are assume to be 0,0,0,FF
You need to specify a colorkey value this way : 0x000000FF
When the loader see the color 0,0,0 in the texture without alpha channel
it will assume it's the color 0x000000FF opaque black (0,0,0,FF)
Now when it will compare to the ColorKey value 0x000000FF it will convert to transparent black 0x00000000
With alpha correctly to 00 so transparent...
It's logical but it's completely twisted...
You load a texture without alpha channel so all color have a alpha FF (including the black)
And are all opaque
After the load which replace the color 0,0,0,FF (0x000000FF) with 0,0,0,0 (0x00000000) transparent black
all color will have a alpha of FF but all your 0,0,0,FF black will be replace with 0,0,0,0...
Now you can use this loaded texture with all the black having a alpha at 00 and all other alpha at FF for all other color
Make sure you have a surface with alpha channel and that you copy the alpha channel too
You must have Texture with alpha channel format too
