Reading & Writing to textures in HLSL 5.0 (deferred shading)

Question

I am trying to achieve deferred shading in DirectX 11 , c++. I have managed to create the G-Buffer and render my scene to it(Checked with "GPU PerfStudio"). I am having difficulty with final lighting stage. I am not able to read from textures(Diffuse,Normal,Specular) using SV_Position returned coordinates.

This is the pixel shader used to render light as shapes.

Texture2D<float4> Diffuse   : register( t0 );
Texture2D<float4> Normal    : register( t1 );
Texture2D<float4> Position  : register( t2 );

cbuffer MaterialBuffer : register( b1 )
{
    float4 ambient;
    float4 diffuse;
    float4 specular;
}
//--------------------------------------------------------------------------------------
struct VS_OUTPUT
{
    float4 Pos : SV_POSITION;
    float4 PosVS:   POSITION;
    float4 Color : COLOR0;
    float4 normal : NORMAL;
};

float4 main(VS_OUTPUT input) : SV_TARGET
{

    //return Diffuse[screenPosition.xy]+Normal[screenPosition.xy]+Position[screenPosition.xy];
    //return float4(1.0f, 1.0f, 1.0f, 1.0f);
//--------------------------------------------------------------------------------------
    //Problematic line
    float4 b=Diffuse.Load(int3(input.Pos.xy,0));
//--------------------------------------------------------------------------------------
    return b;
}

I have checked with "GPU PerfStudio" the input textures are properly bound.

The above code is returning the color I used to clear the texture.(From my debugging I have found that its returning value at pixel location 0,0)

If I replace the problematic line with:-

float4 b=Diffuse.Load(int3(350,300,0));

Then its rendering the value at 350,300 pixel location with the proper shape of light.

Thanks

Answer 1

Do you tried with the debug flag D3D11_CREATE_DEVICE_DEBUG at device creation and looked at the output log. You may experience signature mismatch between the Vertex and the Pixel stages. It would explain why the sv_position semantic do not behave correctly.

Answer 2

I solved the problem.I was using the same z-buffer for rendering light geometries that I had used previously for G-buffer.

Thank you for your response.