Ok, first thanks for pointing me into the right direction. However I'm still a bit confused. I guess the "Dest" color is the color which is already in the framebuffer, the "Src" color is the value that gets computed by the pixel shader.
I want to do a transparent water surface with a terrain underneath. But when I use
Code:
 
		AlphaBlendEnable=True;
		SrcBlend=SRCALPHA;
		DestBlend=INVSRCALPHA;

with out.a set to 0.5, I don't see any of the terrain under the water surface. The surface appears to be like without the code.

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