Variable model_300_fragConst
model_300_frag: "#version 300 es\n#ifdef GL_FRAGMENT_PRECISION_HIGH\n precision highp float;\n#else\n precision mediump float;\n#endif\nuniform float u_opacity;\nin vec3 front_color;\nin vec3 back_color;\nout vec4 outColor;\nvoid main () {\n\tgl_FragDepth = gl_FragCoord.z;\n\tvec3 color = gl_FrontFacing ? front_color : back_color;\n\toutColor = vec4(color, u_opacity);\n}\n" = ...