DirectX HLSL shader implicit truncation of vector type error

Question

Hi I'm getting an error in one my pixel shaders, implicit truncation of vector type.

Here is the code causing the error:

float3 colour = 0;
float3 ppColour = SceneTexture.Sample(PointSample, ppIn.UV);
float4 col = SceneTexture.Sample(PointSample, ppIn.UV);
float intensity = 0.0f;
float r = SceneTexture.Sample(PointSample, ppIn.UV).r;
float g = SceneTexture.Sample(PointSample, ppIn.UV).g;
float b = SceneTexture.Sample(PointSample, ppIn.UV).b;
float a = SceneTexture.Sample(PointSample, ppIn.UV).a;
intensity = r + g + b + a;

if (intensity > 5.0f)
{
    for (int count = 0; count < 13; count++)
    {
        colour += SceneTexture.Sample(TrilinearSampler, ppIn.UV + PixelKernel[count] * BlurStrength) * BlurWeights[count];
    }
    return float4(colour, 1.0f);
}

return float4(ppColour, 1.0f);

If I comment out intensity = r + g + b + a; then the project compiles. Can anyone see what I'm doing wrong, thanks.

Solution

The reason you get this error is, that you are mulitplying/adding up float3's and float4's. You should 'cast' float3 to float4 with float4(float3, 1.0f) or float4.xyz (which makes it float3)