HLSL tex2d border problem
Author
hi,all,
just a strange problem in HLSL,
float4 alpha = tex2D(WipeAlphaCueSampler,float2(0,0));
//it should return the first column data of texture, but it return a grey value.
float4 alpha = tex2D(WipeAlphaCueSampler,float2(0.000001,0));
//here it can return the first column data
so any answer with that?
I use GF 9600GT。
and I try ps_3_0 , ps_2_0 , both same problem.
//below is the code ======================================================
texture WipeAlphaCue;
sampler WipeAlphaCueSampler =
sampler_state
{
Texture = <WipeAlphaCue>;
MipFilter = LINEAR;
MinFilter = LINEAR;
MagFilter = LINEAR;
};
float4 wipePS(WipeVertexOutput IN) : COLOR
{
float4 alpha = tex2D(WipeAlphaCueSampler,float2(0.0000001,0));
return alpha;
}
technique RenderScene
{
pass p0
{
PixelShader = compile ps_2_0 wipePS();
}
}
I suspect you're getting caught in the pixel addressing issue.
Under D3D9 the centre of the pixel is at 0.5,0.5 - thus a UV of 0,0 is actually above-left from the top-left pixel. If you have wrapping enabled then it'll actually sample from all 4 corners of the texture!
Have a look at the "Directly Mapping Texels to Pixels" article in the SDK, it should provide valuable insight. In short, offsetting by 1/2 a pixel in the U and V directions should get you what you want. Otherwise you need to go for point sampling (might actually be better if you're using lookup textures) or different clamping/wrapping modes.
hth
Jack
Under D3D9 the centre of the pixel is at 0.5,0.5 - thus a UV of 0,0 is actually above-left from the top-left pixel. If you have wrapping enabled then it'll actually sample from all 4 corners of the texture!
Have a look at the "Directly Mapping Texels to Pixels" article in the SDK, it should provide valuable insight. In short, offsetting by 1/2 a pixel in the U and V directions should get you what you want. Otherwise you need to go for point sampling (might actually be better if you're using lookup textures) or different clamping/wrapping modes.
hth
Jack
Author
Thanks jollyjeffers,
I try with
AddressU = Clamp;
AddressV = Clamp;
problem is resolved, thanks very much. :)
I try with
AddressU = Clamp;
AddressV = Clamp;
problem is resolved, thanks very much. :)
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