model_300_vert: "#version 300 es\nuniform mat4 u_modelView;\nuniform mat4 u_matrix;\nuniform vec3 u_frontColor;\nuniform vec3 u_backColor;\nin vec3 v_position;\nin vec3 v_normal;\nout vec3 front_color;\nout vec3 back_color;\nvoid main () {\n\tgl_Position = u_matrix * vec4(v_position, 1);\n\tvec3 light = abs(normalize((vec4(v_normal, 1) * u_modelView).xyz));\n\tfloat brightness = 0.5 + light.x * 0.15 + light.z * 0.35;\n\tfront_color = u_frontColor * brightness;\n\tback_color = u_backColor * brightness;\n}\n" = ...