Original Post
I was just daydreaming about shadowmap artefacts and was wondering if anyone has tried rotating shadowmap texels to match the normal of the geometry being checked (in the draw phase). I guess the reason for the artefacts are that each shadow map 'texel' (not pixel), when slightly scaled up sits on same plane as the near (and far) plane of the light frustum.
If you're checking a particular pixel is in shadow on a model's polygon which is almost perpendicular to the normal of the shadowmap, the shadow map texel will effectively 'stick out' of the polygon creating the artifact. Can we somehow rotate the whole shadowmap texel to match the polygon's normal and sample from that rotated texel instead? By sample, I mean take the centre point of the shadowmap texel and calculate what the depth would effectively be in any area of the texel when rotated...
If you're checking a particular pixel is in shadow on a model's polygon which is almost perpendicular to the normal of the shadowmap, the shadow map texel will effectively 'stick out' of the polygon creating the artifact. Can we somehow rotate the whole shadowmap texel to match the polygon's normal and sample from that rotated texel instead? By sample, I mean take the centre point of the shadowmap texel and calculate what the depth would effectively be in any area of the texel when rotated...