Emissive maps support

[JungHsuan]

Requirements:

Please go through this checklist before opening a new issue

• [x] Review the documentation
• [x] Search for existing issues in: viromedia/viro & ViroCommunity/viro
• [x] Use the latest ViroReact release

Environment

Please provide the following information about your environment:

1. Development OS: Mac
2. Device OS & Version: Android 11, pixel 4 and iOS 14.5, iPhone 11
3. Version: ViroReact version: 2.20.2, react native version: 0.63.4

Description

Emissive texture is not showing.

Reproducible Demo

try this model on my Pixel 4:

Screenshot from glTF Viewer

Debuging with emissive channel by glTF-Sample-Viewer

[robertjcolley]

Can you also share a minimal reproduction with this model? I've been reproducing issues in https://github.com/NS-BOBBY-C/starter-kit which will help us fix the issue;.