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[SlimDX] Blending woes.

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Hi everyone,


I'm having trouble getting an edge detection shader to blend with the previously rendered image.


Quick background:

I render a GBuffer (color, normal depth)

I then render an image with just direct and ambient light values (to the 

Finally I use the normal and depth map from the GBuffer to create my edges.


Everything works fine when I render just the GBuffer and lighting.  I get this:



When I render just the edge detection shader I get this:



When I add in edge detection after the lighting render I get this:



I am stumped.  I don't think its actually a blending issue.  I set the BlendState on the shader with this:


BlendState SrcAlphaBlend
   BlendEnable[0]           = TRUE;
   SrcBlend                 = SRC_ALPHA;
   DestBlend                = INV_SRC_ALPHA;
   BlendOp                  = ADD;
   SrcBlendAlpha            = ONE;
   DestBlendAlpha           = ONE;
   BlendOpAlpha             = ADD;
   RenderTargetWriteMask[0] = 0x0F;


I have a DepthStencilView set when I do the GBuffer render, but not when I do the lighting and edge detection.


Any ideas?

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Well, this one should have been a no-brainer.


The output from my gbuffer pass had all zeros in the alpha channels.  So when I set the blendstate to alpha on the edge detection shader my gbuffer started outputting completely transparent color.


Here's what it looks like all combined.



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