Hi there, I am rendering my game to render textures but I am having difficulty figuring out how to scale it to fill the window.  The window looks like this:

and the render texture looks like this (it's the window resolution downscaled by 4):

(I implemented a screenshot function of the render texture which has proved to be very useful getting this working so far).

My vertex shader is the classic "draw fullscreen triangle without binding a vertex or index buffer" as seen many times on this site:

PS_IN_PosTex main(uint id : SV_VertexID)
{
    PS_IN_PosTex output;
    output.tex = float2((id << 1) & 2, id & 2);
    output.pos = float4(output.tex * float2(2, -2) + float2(-1, 1), 0, 1);
    return output;
}

and the pixel shader is simply:

Texture2D txDiffuse : register(t0);
SamplerState samp : register(s0);

float4 main(PS_IN_PosTex input) : SV_TARGET
{
    return txDiffuse.Sample(samp, input.tex);
}

Can someone please give me a clue as to how to scale this correctly?

Many thanks,

Andy

OK, fixed it.  Beginners mistake.  I had forgotten to set the viewport of the window before rendering from render texture to window