There is a texture getting mistakenly drawn in my 5 way blending materials blending space and I can´t figure out why.


I have an urgent problem with a 5 way blend material. I strictly followed the documentation on this as it is written here: Create a Material for 5-Way Texture Blends | Unreal Engine Documentation

Somehow, the fith texture (path) gets drawn within the blending area between the other textures and I can´t really figure out the reason of this. I double checked everything and everything seems correct to me. The only modification that I did was to multiply a global AO/Normal on top of the textures. Does anyone have a clue of what is going on? :slight_smile:
Thanks in advance!

The problem is shown on the little picture above. The numbers stand for the used texture within the material.

Texture 1 and texture 5 are both driven by the alpha channel.
Texture 5 is 1-alpha and texture 1 is alpha. They blend near 0.5. If you’ve painted with zero alpha for texture 2, then that alpha channel will wind up being interpolated across the border between texture 2 and texture 1. Which means the value will go across the 0.5 range where both 1 and 5 are half blended in (1-0.5 is 0.5) .

3 options. Add more geometry, reorder your materials, or do some more math to split the alpha channel into two gradients. Material 5 can use one minus alpha x 2 for its lerp, material one could use (alpha - 0.5) x 2 clamped to 0-1
That would make a hard switch between Material 5 and Material 1. So long as you don’t want those 2 to blend, you can remove or minimize the unwanted blending issue with other textures.