What is causing this error?
[Cesium WebGL] Shader program link log: ERROR: Implementation limit of 16 MAX_VERTEX_ATTRIBS (e.g., number of generic plus conventional active vec4 attributes) exceeded, shader uses up to vec4 attribute 499.
[Cesium WebGL] Translated vertex shader source:
[Cesium WebGL] Translated fragment shader source:
An error occurred while rendering. Rendering has stopped.
RuntimeError: Program failed to link. Link log: ERROR: Implementation limit of 16 MAX_VERTEX_ATTRIBS (e.g., number of generic plus conventional active vec4 attributes) exceeded, shader uses up to vec4 attribute 499.