Thread by @delaneykingrox

Okay #gamedev #gameArt DM question- how important is padding on textures? What should they be set to?

So padding in game textures is exactly like 'bleed' in printing.

With printing, you can't be certain exactly where the cuts to the paper will fall precisely, so you need to have a little extra color extending past the borders. This is called 'bleed'.

With game textures, you need the colors to extend past the boundaries of your textured pieces because the pixels in the textures become averaged with filtering.

A texture usually contains the full resolution texture, then several MIP map levels- which are halved each time.

So a 1024x1024 texture contains MIPs for 512x512, 256x256, 64x64, 32x32, 16x16 and so forth.

Each time you scale down the image, the pixels are averaged together with their neighbours using your selected algorithm.

This is why you need to extend color past your border.

So the technique we use to protect the edges is called 'dilation'- basically stretching out the border pixels out. "Infinite dilation" stretches the pixels out until they meet another pixel.

So how many pixels do you need?

Well this depends on the size of the texture. You want at least one row of pixel dilation for every MIP you are expecting. So a 2048 square map needs around eight pixels of dilation padding between UV texture islands.

When you deal with transparent objects, dilation becomes a little more complicated, as you need to factor in the MIP maps for alpha, and the edge erosion.

New artists often see dark coloured rims around their leaves because they have pasted the leaves onto a black background.

If you check your texture settings in engine, you will find controls for how to handle your alpha in MIP maps.

If you are using substance painter, the default dilation is "infinite", which is fine for most texturing tasks.

Sometimes you need to turn off dilation when rendering texture masks for baking out opacity, but that is the exception.

Also note that textures WRAP by default, so pixels on the left of your texture average with pixels on the right, and the top pixels with the bottom pixels.
To avoid this, keep your texture islands away from the edges by around four pixels and you should be gold.

I hope that helps.

If you love my tutorials, consider joining my patreon where I will be posting early access to my book.

Patreon.com/darkling

Or tip me a few dollar dollar bills yo at Ko-fi.com/dellak
I will only waste it on frivolities like rent and food