Baking multiple materials into one texture If there are multiple objects with different materials that have been combined into one object, UV unwrapped together and texture baked, the result is glitchy at best. Here is my process:


I start out with everything as a single material with a single UV map and multiple materials. There are three separate pieces in the combined mesh:





I create a new material, a new 4096x4096 image, and a new UV map (through smart projection) that doesn't overlap. I select the image, the new material, the new UV map. Every piece of magic I can think of since I don't know exactly how the bake knows what to bake where:





I click bake, with the sample size set to 256. Nothing is baked to the image I created and selected:





Some stuff baked, but not all of it, and what little was baked was baked to two new images it created:




I don't know what's going on here.
To make this work properly, you need to have an active Image Texture with your new image file in each material you have in this model. Basically, what you have to do now, is to CTRL+C on Image Texture in Everything material, visit each other material and CTRL+V. Then baking will give you appropriate result.