Vertexshader
{
   output.pos = mul(inPos, xMatWVP);
   output.screenPos = ??
}


Pixelshader
{
   (...)
   color.rgb *= tex2D(ScreenMapSampler, input.screenPos);
}

   OUT.vScreenCoord.x = ( OUT.vPosition.x * 0.5 + OUT.vPosition.w * 0.5 );
   OUT.vScreenCoord.y = ( OUT.vPosition.w * 0.5 - OUT.vPosition.y * 0.5 );
   OUT.vScreenCoord.z = OUT.vPosition.w;
   OUT.vScreenCoord.w = OUT.vPosition.w;

Quote:Why not pass in the coordinates as per-vertex attributes? That's the typical way of doing things.

Quote:Alternatively, output.pos = mul(inPos, xMatWVP); should place your geometry in projection space. This is defined in [-1..+1] range, which requires only a little massaging to be in [0..1] texture space...

output.screenPos.x = output.pos.x / output.pos.w / 2.0f plus 0.5f;output.screenPos.y = -output.pos.y / output.pos.w / 2.0f plus 0.5f;

Quote:Original post by Viperrr
Hi,

I have a texture the size of my screen (1280x1024) which I want to sample in my pixelshader, to blend it with the rendered scene. Now I'm having trouble converting the projected pixel coords to sampling coords.
Can someone help me figure this out please?

struct psInput {    //    // add your data here    //    float2 screen : VPOS;};// pixelshadervoid ps(in psInput input, out psOutput output){    // "input.screen" contains the current pixel position is screenspace.    float2 tex = float2((input.screen.x + 0.5f) / 1280.0f, (input.screen.y + 0.5f) / 1024.0f);    // now you can use "tex" as your texture coordinate to sample your texture.    // ...}