[SOLVED] About downsampling in shaders

Graphics
1

Hi !
I’m working on an effect that uses a really low resolution to speed up things.

But when I draw the final image, which is drawn from, say… at the lowest size, an RT of 320x200, onto a 1280x720 RT, some pixels are intermitent due to the size reduced and not always being interpolated correctly.

How to deal with that ? If I use a 4x smaller size, do I need to do many textures fetches around the current pixel to keep the max of them ? 16 texture sampling to sample the square around the current pixel +1 for the pixel ?
Is it better to sample in square ? Diamond ?

2

So no one has any tip/ advice ?

3

The filtering of textures is determined by the minfilter and magfilter settings of the sampler state. In your case it’s the magfilter because you are scaling up. Did you set this to linear?

What type of interpolation are you looking for? If you want something more advanced than linear interpolation, then yes, you would sample pixels around you and interpolate manually.