Matcaps for UE4

[Chronichol]

thanks Sean

@;91400

Chronichol, I’m not exactly sure, but shouldn’t you rotate/flip the vector in your sem shader? Right now if you make a simple matcap with some specific detail “on top of the sphere” and apply it to a spherical mesh in UE, you will see the detail from bellow (I think even left/right is flipped).

I think i know exactly what you are experiencing, the artifact is fixable. I’ll clarify how in a moment. On the other hand there is another apparent byproduct of the FOV on the display of the matcaps, which I’m not sure you are pertaining to as well, It’s entirely logical if you think about the method, and how the surface normals in view space are what the matcap texture is being applied to, so if you see things at sheer left,right, top or down you’ll see the correlating edge colors of the matcap. The bizarre thing is the magnitude of FOVs distortion, which makes some things an issue and feel a bit “weird” and unnatural. Is in essence a byproduct of the fact your screen is a 2D surface, and the fact you are projecting a curved world onto that with FOV, Because let’s think about it for a second, we don’t get barrel distortion in your own periphery do we? so you wouldn’t be able to see surfaces perpendicularity change as significantly as it would on a 2D display. I am curious to see how proportional FOV distortion is on the oculus though worth noting regarding both the artifact and distortion I’ve tested matcaps in 3D software and it’s prevalent there too, it’s down to the fact the model is almost always centered on the screen during your workflow combined with a lower FOV that you fail to notice it.

So yeah the only way to get 1:1 “perfect” display of matcaps would be with orthogonal projection or some level of corrective rotation could theoretically work I will see if it’s worth pursuing, but not sure if it’s justified. I’d speculate it would require taking the screenVectors and using those to determine the corrective rotation, I think it’s possible. but might need to be a different project, to create a FOV correction node

but I believe your issue is the wrap around artifact. which is an artifact caused by the textures tiling method, you need to swap it from wrap to mirror

if you wanted to work with wrapping, you’d need to have uniform borders/rim colour, which is obviously a conflict with the very nature of most matcaps.