GMA 4500MHD - OpenGL - GL_EXT_packed_depth_stencil - Problems

nnexai Mar 24, 2010 6:14 AM

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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 8.15.10.2086 drivers

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

hid Dec 2, 2010 11:03 AM (in response to nnexai)

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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 );
    glFramebufferRenderbufferEXT( GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, rb );
    glFramebufferRenderbufferEXT( GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, rb );

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

Guest Jan 18, 2011 7:08 AM (in response to hid )

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