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  1. Replies
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    If you are drawing something other than GL_POINTS...

    If you are drawing something other than GL_POINTS then I don't think you will see anything. For example a triangle with the same coordinates will not be drawn at all. Try drawing points with the...
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    Actually none. Never owned a Mac to be able to...

    Actually none. Never owned a Mac to be able to judge for myself* but other people did a pretty nice job putting all implementations to the test. So these are my facts:...
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    Thanks for the replies. I thought the drivers...

    Thanks for the replies. I thought the drivers were from nVidia but it seems I was mistaken. Also, the fact that MacOS OpenGL implementation is so buggy probably proves that it's not nVidia.

    It's...
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    Compute shaders on MacOS X

    Hi all,

    I know that MacOS X Mavericks has only GL 4.1 support but is anyone aware if there is hidden support for compute shaders or even a hack-ish way to use them?

    What I am interested to...
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    Sticky: The ARB extensions (bindless texture & sparse...

    The ARB extensions (bindless texture & sparse texture) sound way more interesting/useful compared to the core ones. Also, having updated specs and new extensions backed by ARB every year is really...
  6. There is a video with the presentation. It didn't...

    There is a video with the presentation. It didn't help clear things

    http://www.youtube.com/watch?feature=player_embedded&v=btNVfUygvio
  7. VAOs slower than glVertexAttribPointer on all implementations

    I was reading Valve/nVidia presentation on the lessons learned when Valve ported Source game engine to OpenGL...
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    The driver can do some fancy optimizations inside...

    The driver can do some fancy optimizations inside glMultiDrawElements. For example it can create a new index buffer and issue a single draw call. The worst that can happen is do multiple calls of...
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    I think the rationale behind glMultiDraw is the...

    I think the rationale behind glMultiDraw is the following. If someone disagrees please correct me

    Imagine that you have a single VAO that contains:
    - a big VBO with the geometry of your 3 objects...
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    And what I am trying to say is that by using one...

    And what I am trying to say is that by using one buffer you are not using OpenGL with an optimal way. The sequence you describe has read/write dependency problems because every update to the buffer...
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    I may have an idea on what is wrong. The draw...

    I may have an idea on what is wrong.

    The draw calls are not executed the time you send them. In most implementations they are stacked in a command buffer and the driver decides when to send for...
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    One last question that actually matters. Do you...

    One last question that actually matters. Do you use a single UBO for all the meshes or one per mesh?

    One UBO for all meshes looks like this I guess:


    for mesh in meshes do
    update UBO 0
    ...
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    What do you mean by "Now I switched to a constant...

    What do you mean by "Now I switched to a constant buffer"? Do you have a single buffer with 625 matrices?

    I've done some benches myself on UBOs and I found them slower that glUniform* for these...
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    From what I remember you don't need to protect...

    From what I remember you don't need to protect the shared resources. The implementation should do that for you. Nevertheless there are other things you should worry about (at least on GLES 3.0) like:...
  15. It a bit difficult to root the performance...

    It a bit difficult to root the performance problem but from what you describe you may have this situation:

    1. Render to texture 0
    2. Switch to another FBO and readpixels from texture 0

    The (2)...
  16. One thing you can do is use instancing for...

    One thing you can do is use instancing for batched lights. This may improve things a bit. One bad thing with this implementation of deferred shading is that you speak allot with the API, also you...
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    A few ideas that are based 3 things (1) minimize...

    A few ideas that are based 3 things (1) minimize GL calls (2) minimize state switching (3) better caching:

    Using UBO will be better especially if you have many uniforms per program. You save the...
  18. Re: why does SwapBuffers take up so much cpu time?

    It's _probably_ because allot of synchronization stuff happen when you swap buffers. I'm not sure though, maybe someone has a more concrete answer than mine.
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    Re: Transform Feedback problem

    You need to inform the shader about the transform feedback varyings _prior_ linking it. In GL 3.x you glTransformFeedbackVaryings and then you link.
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    Re: Create second context

    I've made some tests with SDL but nothing's conclusive at the moment. When I have a solution I will post it here.
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    Create second context

    Im using SDL 1.3 to create a window and a rendering context for that window (see this tutorial)

    I want to create a second context for texture loading in a separate thread (according to OGL 3.3...
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    Re: FBO depth map almost completely washed out

    The depth buffer keeps values from 0.0 to 1.0 but not in linear manner but in exponential. This practically means that if you visualize it it will be black in pixels very very close to the camera.
    ...
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    Re: Manual mipmap loading

    According to http://www.opengl.org/wiki/Texture#Mipmap_range we round up.
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    Re: Manual mipmap loading

    You write "8x2, 4x1, 2,1" you mean "8x2, 4x1, 2x1"??

    What is the condition to stop generating mipmaps? Actually, what is the algorithm that calculates the width and height for every level?
    ...
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    Re: Manual mipmap loading

    First of all sorry for the late update, due to lack of time I've tested it yesterday.

    I've tried to specify the textures for every mipmap level using glTexImage2D. I didnt create any mipmaps with...
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