Is there anyway to filtere a texture in glsl that turns stair like texels into smooth lines

Question

I'm trying to filter a static, low resolution shadowmap. Unfortunatly, it doesn't look smooth, because of the way the default trilinear filtering works.

It does have a smooth transition from light to shadow, but you can still see pixelation in the texture. Now I am wondering if there are some techinques to hide these blocky texels with some custom filtering tricks, and make it look a bit more natural.

Imagine a low resolution texture with a 2 pixel wide, perfectly diagonal line. Now I'd like this texture to be rendered in a way that makes the line look like it was actual a high resolution line, by basicly filling all the hard edges between the background and the line with triangles facing towards the line, in order to make it look smoother.

Is there some custom filtering trick that allows me to make my shadowmaps look just a bit more anti-aliased?

Answer 1

There is, it's called PCF (Percentage Closer Filtering). There are good tutorials on it, too.

Another way are variance shadow maps, however they are more complicated to understand. There are good video tutorials for both by "thebennybox" on YT, I found those really helpful.