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### #ActualAussieSpoon

Posted 29 November 2013 - 09:11 PM

Hello,

I am trying to set up alpha to coverage in DirectX 11. I am currently rendering a particle system using instancing and a geometry shader, so that I pass in a point (1 vert) to render all the particles of that particle system. This is what it looks like:

I'm trying to set up alpha to coverage but I can't seem to do so. I am getting a problem where it renders a black quad at the particle systems position

Here is the Alpha to coverage blend state:

D3D11_BLEND_DESC alphaToCoverageDesc = {0};
alphaToCoverageDesc.AlphaToCoverageEnable = true;
alphaToCoverageDesc.IndependentBlendEnable = false;
alphaToCoverageDesc.RenderTarget[0].BlendEnable = false;

result = device->CreateBlendState(&alphaToCoverageDesc, &AlphaToCoverageBS);


And this is what it looks like:

Even when I try to imitate it within the pixel shader with dithering it produces a similar error:

So I was wondering if it has anything to do with instancing or the geometry shader? I can't imagine it is but I have no idea. Any one think of any reason for this.

If this is too vague just say

Thanks

### #1AussieSpoon

Posted 29 November 2013 - 09:11 PM

Hello,

I am trying to set up alpha to coverage in DirectX 11. I am currently rendering a particle system using instancing and a geometry shader, so that I pass in a point (1 vert) to render all the particles of that particle system. This is what it looks like:

I'm trying to set up alpha to coverage but I can't seem to do so. I am getting a problem where it renders a black quad at the particle systems position

Here is the Alpha to coverage blend state:

D3D11_BLEND_DESC alphaToCoverageDesc = {0};
alphaToCoverageDesc.AlphaToCoverageEnable = true;
alphaToCoverageDesc.IndependentBlendEnable = false;
alphaToCoverageDesc.RenderTarget[0].BlendEnable = false;

result = device->CreateBlendState(&alphaToCoverageDesc, &AlphaToCoverageBS);


And this is what it looks like:

Even when I try to imitate it within the pixel shader with dithering it produces a similar error:

So I was wondering if it has anything to do with instancing or the geometry shader? I can imagine it is but I have no idea. Any one think of any reason for this.

If this is too vague just say

Thanks

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