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jeremie009

arbitrary texture coordinates

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I'm trying inside a loop accessing a texture color using arbitrary coodinates. 

 

My texture can map properly to a mesh but I can't seem to sample them without using the mesh uv coodinate. 

while (count <= size)
{
	int x = (int)(count % w);
	int y = (int)(count / w);
	float2 uv = float2(x, y);
			
	float3 = col.Sample(texturesampler, uv).rgb;
count++;
}

the color output is always wrong. like its only sampling one color

 

this is my sampler description 

SamplerStateDescription
            {
                AddressU = TextureAddressMode.Clamp,
                AddressV = TextureAddressMode.Clamp,
                AddressW = TextureAddressMode.Clamp,
                BorderColor = new Color4(0, 0, 0, 0),
                ComparisonFunction = Comparison.Never,
                Filter = Filter.MinLinearMagMipPoint,
                MaximumLod = float.MaxValue,
                MinimumLod = 0,
                MipLodBias = 0.0f
            }

so I'm wondering if there it can be done or if I have to use something like sampleGrad. 

 

 

 

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What exactly are you trying to do ?

There are several pitfalls in your shader code.
1. float3 = col.Sample(texturesampler, uv).rgb;
This will not compile, will it (ok, I'm not familiar with hlsl) ? Do you want to sum it up, average it or get the last color ?

2. float2 uv = float2(x, y);
This will always contains integers, that is 0,1,2,3...
So, using clamp this will always sample the border of the texture ! You should apply an offset/scale accordingly, depending on what your goal is.

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ok It actually compile. but I realize I totally forgot how uv coordinates were mapped. So there I just need to subdivide by height and width. 

 

Thanks. 

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