DirectX HLSL - Constant Buffer empty in Pixel Shader but not Vertex Shader

Question

I am in the process of implementing lighting in my DirectX 11 project. The problem I have is that when I try to access a cbuffer value from the Pixel Shader function it's just returning float3(0, 0, 0) meanwhile when I access the same value in the Vertex Shader function it returns the correct value. Here is the shader:

/*********************************************\
                 VERTEX SHADER
\*********************************************/

//Constant buffers
cbuffer Object : register(cb0) {
    float4x4 WorldMatrix;
};
cbuffer Camera : register(cb1) {
    float4x4 ViewMatrix;
    float4x4 ProjectionMatrix;
};
cbuffer LightBuffer : register(cb2) {
    float3 AmbientColor;
}


//IO Structs
struct VS_INPUT {
    float3 Position : POSITION;
    float2 UV : TEXCOORD;
    float3 Normal : NORMAL;
};
struct VS_OUTPUT {
    float4 Position : SV_POSITION;
    float2 UV : TEXCOORD;
    float3 Normal : NORMAL;
};

VS_OUTPUT VS(VS_INPUT input){
    VS_OUTPUT output;

    float4 Position;

    //Multiply position with AmbientColor (should be 1, 1, 1), position unchanged
    Position = mul(ViewMatrix, float4(input.Position * AmbientColor, 1));
    Position = mul(ProjectionMatrix, Position);
    Position = mul(WorldMatrix, Position);

    output.Position = Position;
    output.UV = input.UV;
    output.Normal = mul(WorldMatrix, input.Normal);
    return output;
}

/*********************************************\
                PIXEL SHADER
\*********************************************/

SamplerState TextureState;
Texture2D<float4> Texture;
float4 PS(VS_OUTPUT input) : SV_TARGET {
    float4 MaterialColor = Texture.Sample(TextureState, input.UV);

    //Multiply color with AmbientColor (should be 1, 1, 1), returns black
    float3 FinalColor = MaterialColor.xyz * AmbientColor;

    return float4(FinalColor, MaterialColor.a);
}

Here's is the value I'm sending (c++):

_LightsUniform.AmbientColor = XMFLOAT3(1, 1, 1); 
DeviceContext->UpdateSubresource(_LightBuffer, 0, NULL, &_LightsUniform, 0, 0);
DeviceContext->VSSetConstantBuffers(2, 1, &_LightBuffer);
DeviceContext->PSSetConstantBuffers(2, 1, &_LightBuffer);

Here is the result: http://i.gyazo.com/357f1ed3ea33e6569ad2346b368cd975.png

And result without multiplying color: http://gyazo.com/b60b385daa94d3373e9552a523928e3f

I can't see what is wrong. Anybody else had the same issue?

Jorah Mormont · Accepted Answer · 2015-02-17 16:16:24Z

4

I found the problem. Turns out that the registers for my cbuffer(s) were wrong, I used cb# where b# should be used. (I misunderstood what was written here: https://msdn.microsoft.com/en-us/library/windows/desktop/hh447212(v=vs.85).aspx)

Wrong code:

cbuffer LightBuffer : register(cb2) {

Changed to:

cbuffer LightBuffer : register(b2) {

answered Feb 17, 2015 at 16:16

Jorah Mormont

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1 Comment

Ray Garner Over a year ago

There is nothing written about this in the docs not understanding why to use the b# syntax.

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