2 Replies Latest reply: Jan 18, 2011 7:08 AM by RSS

    GMA 4500MHD - OpenGL - GL_EXT_packed_depth_stencil - Problems


      Since the new driver release my gma4500mhd now lists support for the ogl extension GL_EXT_packed_depth_stencil. After running a short test OpenGL reports unknown enum if i try to create a renderbuffer using the format GL_DEPTH24_STENCIL8_EXT. It would be nice if someone could explain this to me.


      I'm trying to use a depth and a stencil buffer for a fbo since i bought this laptop without success.

      If someone knows a way to setup a complete fbo with depth and stencil buffer please let me know.


      If needed I'm going to write an example program for GL_EXT_packed_depth_stencil.


      I'm running Windows7 Prof. with the current drivers

        • 1. Re: GMA 4500MHD - OpenGL - GL_EXT_packed_depth_stencil - Problems

          Hello, nnexai.


          I was having probably the same problem with an application at my office today.

          I'm trying to run the app on a laptop with an intel Core i5 and GMA HD graphics, running Windows XP.

          Not sure about the graphics driver version because I'm currently writing this at home.


          Here's a snippet similar to the code I'm having trouble with:


              glGenTextures( 1, &tex );
              glBindTexture( GL_TEXTURE_2D, tex );
              glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, tex_w, tex_h, 0, GL_RGBA, GL_UNSIGNED_BYTE, 0 );
              glGenRenderbuffersEXT( 1, &rb );
              glBindRenderbufferEXT( GL_RENDERBUFFER_EXT, rb );
              glRenderbufferStorageEXT( GL_RENDERBUFFER_EXT, GL_DEPTH24_STENCIL8_EXT, rb_w, rb_h );
              glGenFramebuffersEXT( 1, &fb );
              glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, fb );
              glFramebufferTexture2DEXT( GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, tex, 0 );


          This code works perfectly on other graphics boards I tested: a GeForce 7950 GT, a Quadro FX 4500, and a Radeon HD 4650.


          After wrestling with the code for half a day, I decided that I can find an alternative to the stencil attachment for the application.

          The GMA HD just didn't seem to want to work with the depth-and-stencil extension.


          I think there is a possibility that there's either a bug in the general GMA OpenGL driver's framebuffer module or,

          maybe intel's hardware just plain doesn't support it.

          • 2. Re: GMA 4500MHD - OpenGL - GL_EXT_packed_depth_stencil - Problems

            For us passing in GL_DEPTH_STENCIL_EXT instead of GL_DEPTH24_STENCIL8_EXT in to glRenderbufferStorageEXT worked but it crashed freeing the buffer.