alpha blending in pixel shader
Author
Hi,
I'm using a pixel shader for simple fixed function pipeline tasks to render to a texture and want alpha blending to work.
yet when I return:
return float4(0,0,0,0);
It puts a black blotch on my RenderTarget as opposed to blending with what's already on the surface.
I've set AlphaBlendEnable = true inside the effect file AND as a SetRenderState call before starting the pEffect->Begin().
Appreciate the help,
Thanks.
Author
yeah, inside the effect file and outside via renderstates.
I'm basically trying to shadow map sprites that are on quads by turning off Z testing and checking if the alpha > 0 to render a depth to my artificial depth buffer.
Here is my effect file, pretty straightforward:
I basically want to alpha blend with src 0 and dest 1.
I'm basically trying to shadow map sprites that are on quads by turning off Z testing and checking if the alpha > 0 to render a depth to my artificial depth buffer.
Here is my effect file, pretty straightforward:
float fFarPlane = 9999.f;float4x4 mWorld : WORLD;float4x4 mViewProj : VIEWPROJECTION;//// normal texture lookup//texture Texture;sampler2D TextureSampler = sampler_state { Texture = <Texture>; MinFilter = Linear; MagFilter = Linear; MipFilter = None; AddressU = Clamp; AddressV = Clamp;};///////////////////////////////////////////////////////struct VS_INPUT{ float4 Pos : POSITION; float3 Tex : TEXCOORD0;};struct VS_OUTPUT{ float4 Pos : POSITION; float2 Tex : TEXCOORD0; float4 PosCopy : TEXCOORD1;};VS_OUTPUT VS(VS_INPUT i){ VS_OUTPUT OUT; OUT.Pos = mul(float4(i.Pos.xyz, 1.f), mWorld); // object space to world space // copy the input texture coordinate through OUT.Tex = i.Tex.xy; // transform position from world space into clip space. OUT.Pos = mul(float4(OUT.Pos.xyz, 1.0f), mViewProj); OUT.PosCopy = OUT.Pos; // copy redundantly for shadow test. return OUT;}// -------------------------------------------------------------// Pixel Shader (input channels):output channel// -------------------------------------------------------------float4 PS_Shadow(VS_OUTPUT IN) : COLOR{ float4 color = tex2D(TextureSampler, IN.Tex); if(color.w > 0.f) { float d = IN.PosCopy.z / fFarPlane; // normalized so between 0 and 1 return float4(d, d, d, 1.f); } else { color.rgb = 1.f; color.a = 0.f; return color; }}//////////////////////////////////////// Techniques specs follow//////////////////////////////////////technique Shadow{ pass p0 { VertexShader = compile vs_2_0 VS(); PixelShader = compile ps_2_0 PS_Shadow(); AlphaTestEnable = true; AlphaBlendEnable = true; SrcBlend = SrcAlpha; DestBlend = InvSrcAlpha; ZEnable = false; ZWriteEnable = false; }}I basically want to alpha blend with src 0 and dest 1.
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