Question Strange noise when sample texture3D

Hi,

I'm trying to sample a 3d texture on a simple cube. However, I get really strange noise artefacts when the filter mode is set to Point. When I set this to bilinear or trilinear, this is not the case. However I want to see the sharp pixel not a blurred result.

 

The interpolated values the fragment shaders receive are going to have a small amount of noise for any value not 0.0 on all vertices. This is just the nature of interpolating floating point values. This means if a value is 1.0 on all vertices, the value the fragment gets will be slightly less than 1.0, slightly more than 1.0, and sometimes 1.0. And for your case if the y is slightly above 1.0 it’ll go to the texel above the one you want.

 

Thanks. So there is no way to get the 3d texture sampled correctly on all sides in the fragment? Or how can I get rid off the noise?

 

The "best" option is probably to inset the sample position slightly. Like subtract the surface normal * 0.001 from the position.