I just wanted to paint a "Bump Texture" in "Material Preview Mode" (EEVEE) but instead of using the "Image Texture" Blender just paints the falloff of my brush. Am I doing something wrong or can't Blender do this in this mode?
If I change the "Stroke Method" from "Space" to "Dots", then the texture seems to have an effect but Blender still mixes it with the "Falloff" of the brush:
I've found this here on CGCookie concerning "Bump Texture" painting in Blender 2.8 but it doesn't show my problem with the "Falloff" mixed into the brush.
Finally, I could solve the problem:
I had the "Blend Mode" of my brush set to "Multiply" which for some strange reason mixes in the "Falloff" of the brush. Since the "First Brush Color" was set to "Black", the "Brush Image Texture" didn't have any effect:
With "Blend Mode" set to "Mix" and the "First Brush Color" set to 100% "White", the brush texture becomes visible:
You can invert the effect by checking the "Invert" box in the "Bump Node" of your material:
One thing to note about Eevee and bump maps is that 8-bit bump textures are notoriously pixelated with Eevee. I've started using 16-bit textures when painting in Blender / Eevee to remedy this issue.
By default, images created in Blender (Image > New Image) should be 16 bit but will change if A) checking the 32-bit float option in the new image options or B) saving the texture file as an 8-bit jpg / png which is what I did in this course.
For diffuse color textures it shouldn't be a big deal but at least your bump textures should be 16 bit.
Thanks, @theluthier, for this hint.!Another option that I will try when painting this "Bump Map" in Blender is the "Stencil Texture Mapping Mode" so that I can rotate my texture or squeeze it horizontally or vertically if this makes a nice effect.