0 Replies Latest reply on Aug 9, 2017 8:08 AM by matust

    OpenGL non-conforming behaviour: Not adding first to gl_VertexID in glMultiDrawArraysIndirect

    matust

      Hello,

       

      I am posting this since I could only find very old and unanswered questions on this forum and elsewhere about this issue. It is about

      non-conforming behavior in AMD drivers. According to OpenGL spec:

      ... gl_VertexID. The vertex ID of the ith element transferred is first + i.

      However, when I use MultiDrawArraysIndirect and fill first attribute (other than 0), it is effectively ignored.

       

      This hinders usage of full vertex pulling, where indices and vertices are stored in buffers for all objects and

      accessed based on gl_VertexID, where first is index into beginning of objects indices.

       

      Can anyone else confirm this issue? And if yes, how can this reach AMD driver team? (supposing that this is

      indeed a bug and not a deliberate choice made due to some backwards compatibility)

       

      System:
      OS: Windows 10 (Creators update) 64-bitRadeon Software Version: 17.7.2

      GPU: Sapphire R7 260X OC 2 GB

      OpenGL context: 4.5 Core

       

      For comparison, my code worked (gl_VertexID filled correctly) on nvidia 765m in my laptop.

       

       

      previous:

      glDrawArraysIndirect not setting gl_VertexID correctly?  ( 2013 )

      OpenGL Discussion and Help Forums (2010