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Type: Posts; User: malexander

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    Perhaps try breaking up the VBOs into smaller...

    Perhaps try breaking up the VBOs into smaller buffers and issue several draw calls. I ran into a similar performance issue with a very large mesh (20M points, 80M verts). Breaking the mesh into...
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    I would render to 20 different textures using...

    I would render to 20 different textures using FBOs, then draw each view as a textured quad, in one OS window. Then you only have to worry about 1 swapbuffers call, once all of the FBOs have finished...
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    You can increase the resolution of your shadow...

    You can increase the resolution of your shadow map texture to reduce the blockiness.
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    1) There is no version of the core profile where...

    1) There is no version of the core profile where you can avoid VAOs. You can bind a VAO at startup and leave it bound in the context for the entire program duration, though. Then you can set vertex...
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    With the vertex buffers: are you just uploading...

    With the vertex buffers: are you just uploading buffer contents when drawing these small batches? Or are you also setting up the vertex state as well (glVertexAttribPointer)? I'd expect a buffer...
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    Do you have a usage scenario for this extension,...

    Do you have a usage scenario for this extension, such as an algorithm that would be accelerated by it? The reason I ask is because over the years I have run into very few cases where points, lines,...
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    "Theoreticians" - this is a pretty bold...

    "Theoreticians" - this is a pretty bold assumption. The members of the OpenGL architecture review board consists of people who design graphics hardware, write graphics drivers, author graphics...
  8. Double-precision computation on many GPUs,...

    Double-precision computation on many GPUs, especially consumer versions, is often much slower than single-precision, by anywhere from 2x - 24x slower. I believe the GT640 FP64 performance is 1/24th...
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    As long as you're only targeting AMD and Nvidia...

    As long as you're only targeting AMD and Nvidia cards on Windows or Linux, you can use a GL4.4 compatibility context. However, if you intend to every support GL3/4 features with Windows/Intel...
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    I've found exactly the same thing, whether it be...

    I've found exactly the same thing, whether it be mapping a buffer for read or write. I've been replacing all glMapBuffers()'s I can find with glSubBufferData() and getting a nice little performance...
  11. I don't see the code that's actually doing the...

    I don't see the code that's actually doing the draw call. Are you using an instanced draw method (glDrawArraysInstanced, glDrawElementsInstanced)? Otherwise the instance will always be 0 unless you...
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    There are dvec's that can use up to 8N, and...

    There are dvec's that can use up to 8N, and perhaps they were future-proofing the feature for other types that may exceed the size of a vec4.
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    While rule 2 of the std140 spec say the base...

    While rule 2 of the std140 spec say the base alignment of a ivec2 is 2N, rule 4 specifies the stride for arrays:


    That is where the alignment of 4N is coming from.
  14. You can use the glXSwapInterval(0) function...

    You can use the glXSwapInterval(0) function defined by the GLX_SGI_swap_control extension to disable vsync for your application.
  15. You can use glScissor with an area of 1 pixel at...

    You can use glScissor with an area of 1 pixel at the specified mouse coords. That will crop the render to a single pixel. While this will save on fragment writes, you'll still pay for all vertex...
  16. I ran into an AMD driver bug where -1 for the...

    I ran into an AMD driver bug where -1 for the string length was being rejected as an invalid value, instead of indicating a NULL-terminated string. Passing strlen(msg) worked around the issue. Not...
  17. If you print the result of...

    If you print the result of glGetString(GL_RENDERER) in your app, do you get the nvidia or MESA driver?
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    There's no standard gl call to query memory or...

    There's no standard gl call to query memory or memory use, but you can try the AMD and Nvidia specific extensions:

    http://www.opengl.org/registry/specs/ATI/meminfo.txt...
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    Try reading this tutorial on drawing with VBOs: ...

    Try reading this tutorial on drawing with VBOs:

    http://www.arcsynthesis.org/gltut/Basics/Tutorial%2001.html

    It draws a single triangle, and is quite good at introducing the concept of drawing...
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    It looks from your code like you're rebuilding...

    It looks from your code like you're rebuilding the model every time you move it. You don't need to do this unless the model itself is deforming, and this is the source of your performance loss....
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    The only way I know of doing this in unextended...

    The only way I know of doing this in unextended GL is to use a geometry shader in conjuntion with a texture buffer object containing the UV coords. It requires that your model be all triangles, or...
  22. That's probably the bug then, in the first...

    That's probably the bug then, in the first example v3.w would be 2 and not 1, messing up any perspective divide.
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    This is especially true for AMD cards. While they...

    This is especially true for AMD cards. While they report a GL_MAX_VERTICES of 2^32-1, and GL_MAX_ELEMENTS_VERTICES of 2^24-1 (16M), if you use multiple vertex buffers with sizes greater than roughly...
  24. That's a good point, you do have to check the...

    That's a good point, you do have to check the GL_LINE_WIDTH_RANGE (or GL_SMOOTH_LINE_WIDTH_RANGE, if you are using smooth lines). Both AMD and Nvidia drivers on Linux and Windows support the same...
  25. Again, wide lines are deprecated but not removed...

    Again, wide lines are deprecated but not removed in the Core GL contexts. The GL ARB specifically mentions this in the GL 3.1 spec (Appendix G). Since the ARB went to the trouble of specifically...
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