EXT_primitive_bounding_box : how does Primitive Generator process gl_BoundingBoxEXT
In the definition of Tessellation Primitive Generator, it processes gl_TessLevelOuter and gl_TessLevelInner and generates u,v,w of the relative value within [0..1]. It is not a real vertex location. How does PG process gl_BoundingBoxEXT? What is the function or formula related to gl_BoundingBoxEXT?
Note gl_BoundingBoxEXT is the output of tesselation evaluation stage (not control stage), after the tesselator. So gl_Postion-s are already known when gl_BoundingBoxEXT is considered.
Regarding your question gl_BoundingBoxEXT takes clip coordinates - homogeneus x,y,z,w.
Last edited by scygan; 09-30-2014 at 05:38 AM.