Something wrong with "fit" on decals?

[Tels]

Why is blending even necessary? Tiling textures should already be designed to blend seamlessly.

 

The texture-draw in the hardware will "blend" the pixels because the texture has only so many pixels and it selects a "blend" of certain pixels for each pixel on the screen. So if you use a 32x32 pixel texture, you still get a 1024x768 screen drawn.

 

The "blending" happens to certain rules explained here https://en.wikipedia.org/wiki/Texture_filtering

 

The problem with the decal is, that it is not designed to blend seemlessly in the vertical direction. Which means when drawing pixels near the edge, it is wrong for the shader to select pixels from the "other" side of the texture.

 

I'm not sure if there is a way to stop this (my mind is spotty these days), but I think the "clamp" keyword might be what you are looking for.

[Springheel]

Adding clamp doesn't change anything.

[Tels]

Looking at this:

 

http://www.iddevnet.com/doom3/materials.php

 

"clamp" should be the one that works - so I'm not sure if it is not working, or you maybe did not apply it at the right place or maybe forgot to reload materials? Did you try it in the engine or in DR? (I'm not sure if DR really supports clamp)

 

Btw, "forceOverlays" might be what you are looking for alpha textures for the AI - wasn't there a problem with decals on AI disappearing for certain stages?

[SteveL]

That's indeed what clamp is for. Quoting from Real-Time Rendering: "This function is useful for avoiding accidentally taking samples from the opposite edge of a texture when bilinear interpolations happens near a texture's edge". But even if we get it working I think it would suffer from the problem that grayman mentioned: you'd only get one repetition of a decal on a 1x4 wall, for example, and the other 3 squares' worth of wall would be filled by straight bands formed by repetition of the edge of the decal. Could you place your clamped decal on square patches and duplicate them to fill the space?