1 Reply Latest reply on Jan 19, 2011 11:34 PM by linqunzju

    Geometry shader performance

    AveryYang

      Hi all,

      I have a question when writing a geometry shader code.

      If I use a vertex and generate above 10,000 polygons in geometry shader instead of draw above 10,000 polygons in vertex buffer, is the former's performance better than the latter?

      How can I measure and prove it?

      Thanks for reading patiently.

        • Geometry shader performance
          linqunzju

          - draw above 10,000 polygons in vertex buffer should be faster

          - in theory, vertex shader and geometry shader have the similar performance ( emit vertex per clock), so if you need handle same vertices, the performance should be similar, but actually additional pipeline will hurt the performance.

          - geometry shader output is write to video memory, so use geometry shader can save memory bandwidth.

          - you can use timer query to measure the performance. please reference http://www.opengl.org/registry/specs/ARB/timer_query.txt for detail.