This page provides information on the GLSL Material.
The VRayGLSLMtl can be used to load OpenGL Shading Language GLSL shaders and render them directly with V-Ray.
This material is the first stage of the V-Ray implementation of GLSL support. In this version, the shaders are compiled to byte code for a software virtual machine, which is then interpreted. Due to this run-time interpretation, GLSL shaders can be somewhat slower to render than V-Ray shaders written in C++. In future builds of V-Ray, shaders will be directly compiled to machine code for faster rendering.
UI Path: ||Material Editor window|| > Material/Map Browser > Materials > V-Ray > VRayGLSLMtl