Load a PBR Model

# Itroduction

This example demonstrates loading glTF model with PBR materials. PBR materials are usually used with image based lighting. ClayGL provide method app.createAmbientCubemapLight to load a HDR texture, do prefiltering, and the create an AmbientCubeMap with the prefilerted cubemap for specular lighting. In addition, it will also create an AmbientSH for diffuse lighting using technique called spherical harmonics

See Basic Theory of Physically Based Rendering to know more about PBR.

Damaged helmet model is from glTF-Sample-Models

# Main Code