GL_NV_occlusion_query http://www.opengl.org/registry/specs/NV/occlusion_query.txt GL_NV_occlusion_query GL_PIXEL_COUNTER_BITS_NV 0x8864 GL_CURRENT_OCCLUSION_QUERY_ID_NV 0x8865 GL_PIXEL_COUNT_NV 0x8866 GL_PIXEL_COUNT_AVAILABLE_NV 0x8867 void glBeginOcclusionQueryNV (GLuint id) void glDeleteOcclusionQueriesNV (GLsizei n, const GLuint* ids) void glEndOcclusionQueryNV (void) void glGenOcclusionQueriesNV (GLsizei n, GLuint* ids) void glGetOcclusionQueryivNV (GLuint id, GLenum pname, GLint* params) void glGetOcclusionQueryuivNV (GLuint id, GLenum pname, GLuint* params) GLboolean glIsOcclusionQueryNV (GLuint id)