adding in submeshes and multiple materials into Canvas Mesh Element

Describe the problem

In the canvas mesh element script I can only have one mesh with one materials
the 3D element is one mesh but it needs support for multiple materials

A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
I cannot add multiple materials into the script. This was discovered while scrolling and the cursor wasn't masking properly

Describe the solution you'd like

added material support
A clear and concise description of what you want to happen.

Describe alternatives you've considered

A clear and concise description of any alternative solutions or features you've considered.

Additional context

Add any other context or screenshots about the feature request here.

Beginne damit, die Implementierung von Canvas Mesh Element zu lokalisieren und zu prüfen, wie sie derzeit mit einem Mesh und seinem Material umgeht. Ermittle das Verhalten von Unity-Meshes und Submeshes, das dabei eine Rolle spielt, und definiere den Abschluss so, dass ein 3D-Element mehrere Submeshes und Materialien unterstützt, statt jeweils nur eines.