Importing .mtl files for .obj files

[huynmela]

Hello!

I am attempting to load in a .obj file with its associated textures (.jpeg and .mtl). I am also trying to view this .obj file in 3D using WGLMakie. I have two questions:

1. An issue I am running into when using WGLMakie to view my .obj file with a matcap texture is that the texture does not appear-- instead, the .obj appears completely black (no lighting?). Is it possible to apply matcaps while using WGLMakie?
2. Without WGLMakie, the matcap applys, but in the incorrect areas. I haven't found a way in the docs or online to load in the associated .mtl file with the .obj and .jpeg. Can Makie load in .mtl files?

Below is my sample code. Thanks!

using FileIO, GLMakie, ImageMagick, JSServe, WGLMakie

texture_pic = load(assetpath(joinpath(pwd(), "data", "xx.jpg")))
obj_mesh = load(assetpath(joinpath(pwd(), "data", "xx.obj")))

mesh(
    obj_mesh, matcap=texture_pic,
    figure = (resolution = (700, 1000),)
)

[ffreyer]

1. WGLMakie doesn't have matcaps so it just uses whatever color is set.
2. Maybe you're trying to render a normal texture as a matcap? Try color = texture_pic instead. (Matcaps are textures that use normals to map color onto a mesh. Afaik that usually only includes front facing normals so there isn't much transforming you can do.) The loading is done by FileIO/MeshIO. I'm not aware of any mtl loading capabilities. Makie also doesn't have a clean concept of materials yet (well maybe RPRMakie does)

[SimonDanisch]

We implemented a mtl parser ages ago, but it has been bit-rotting away: https://github.com/JuliaIO/WavefrontObj.jl/blob/master/src/mtl.jl..
Someone would need to revive that code...

Do you really want matcap (pretty much an environment map, used for more interesting reflections), or do you just want a textured mesh?

[huynmela]

@ffreyer @SimonDanisch
I see! My issue was thinking matcaps acted the same as a textured mesh. Changing it to color=texture_pic worked perfectly. Much appreciation to you both, thank you!