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  1. Thread: basic fbo issue

    by Osbios
    Replies
    1
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    106

    I saw two things, did not test the code. This:...

    I saw two things, did not test the code.

    This:

    glTexImage2D(GL_TEXTURE_2D, //target
    1, //level
    GL_RGBA8, //internalformat
    winWidth, //width...
  2. Replies
    3
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    295

    Looks like a simple parameter mix-up to me:...

    Looks like a simple parameter mix-up to me:
    glGetInternalformativ(GLenum target​, GLenum internalformat​, GLenum pname​, GLsizei bufSize​, GLint *params​);
    ->
    glGetInternalformativ(GL_TEXTURE_3D,...
  3. Thread: glDrawElements

    by Osbios
    Replies
    5
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    420

    With that definition glBegin also has a different...

    With that definition glBegin also has a different default behaviour in core profile. ;)
  4. Replies
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    551

    With only one component in your texture you could...

    With only one component in your texture you could use textureGather (ARB_texture_gather) to sample 4 values with one sample.
  5. Thread: glDrawElements

    by Osbios
    Replies
    5
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    420

    glDrawElements and other commands can work on...

    glDrawElements and other commands can work on Vertex Buffers (Always system memory) and Vertex Buffer Objects (Can be in vram).
    Vertex Buffers are the default mode of operation, where the pointer...
  6. glWriteBuffer/glWriteBuffers/glReadBuffer are...

    glWriteBuffer/glWriteBuffers/glReadBuffer are global states and are not bound to framebuffer objects.
  7. A framebuffer can only have one depth and/or one...

    A framebuffer can only have one depth and/or one stencil target. This can be as two separate buffers or as one combination buffer.
    You tell glBlitFramebuffer what combination of depth/stencil/color...
  8. Replies
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    594

    Not to sound like a nitpicker but to clarify...

    Not to sound like a nitpicker but to clarify this, would it not be more accurate to call this creating of the texture framework? Because glTexImage*D/glTexStorage*D are actually "creating" the...
  9. Replies
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    683

    You don't have to sync anything. Blitting will be...

    You don't have to sync anything. Blitting will be put on the command queue.

    Before you can use glCheckFramebufferStatus you actually have to bind the FBO. And the DSA function...
  10. Would this be correct for a 2d texture storage...

    Would this be correct for a 2d texture storage with mipmaps then?:


    int levels = int(ceil(log(max(sizeX, sizeY) + 1)));
  11. Replies
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    2,069

    Drawcalls are the main limit in OpenGL and...

    Drawcalls are the main limit in OpenGL and Direct3D, because of how much the drivers have to do in the background and then hit a CPU limit. Also this has the disadvantage that your application gets...
  12. Replies
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    690

    vertex arrays are basically like vertex buffer...

    vertex arrays are basically like vertex buffer objects used with GL_STREAM_DRAW_ARB as usage hint.

    not vertex array objects but vertex buffer objects, hope I didn't confuse anyone
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    835

    Happily it's close to impossible to damage...

    Happily it's close to impossible to damage hardware this days with normal applications.
    One main design of hardware and software this days is that non expected errors cause a shutdown. Because an...
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    4
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    565

    If you use a black surface as base...

    If you use a black surface as base (glClearColor(0,0,0,0)), you can simply use additive blending. Meaning if you draw the value 20,20,20 two times on a pixel then the pixel will be 40,40,40. Three...
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    498

    I don't see loading or binding of any shaders.

    I don't see loading or binding of any shaders.
  16. Replies
    13
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    1,468

    You can not really map glGetUniformLocation to a...

    You can not really map glGetUniformLocation to a string map because the function does a bit more. For example it will resolve array locations like ARRAYNAME[5]. It also resolves variables from...
  17. Replies
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    683

    In that case you draw the non alpha blending...

    In that case you draw the non alpha blending geometry. Then only disable depth writing with glDepthMask and draw the alpha blending geometry.
  18. Replies
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    683

    To me it looks like you still have depth test on.

    To me it looks like you still have depth test on.
  19. Replies
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    Actually that is exactly what the driver/gpu...

    Actually that is exactly what the driver/gpu does! You autogenerate or upload your own mipmaps with whatever data you like.

    More about performance:

    If you use an 256x256 texture and stretch it...
  20. Replies
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    479

    My guess would be that, except on very old...

    My guess would be that, except on very old hardware, using client-side vertex arrays is no difference then using glBufferData with GL_STREAM_DRAW as usage hint.
    With client side arrays the driver...
  21. Replies
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    855

    Theoretically changing the FBO attachments would...

    Theoretically changing the FBO attachments would cost more then switching between FBOs. (Validation of changed FBO)
    That said, switching between FBOs definitely comes with a cost! Its slower then...
  22. Replies
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    519

    What you are looking for is simple steaming data...

    What you are looking for is simple steaming data from the system memory to the GPU memory. For that you use Pixel Buffer Objects http://www.songho.ca/opengl/gl_pbo.html
    Use 2 or more textures as...
  23. Anisotropy filtering is also limited to the...

    Anisotropy filtering is also limited to the texture and can not be set with samplers. Well, it also still is an EXT function.
  24. Yes, pretty much any! Framebuffer Objects are a...

    Yes, pretty much any! Framebuffer Objects are a core feature since OpenGL 3.0. You only need a valid OpenGL context to use them.
    The only exception are some older crappy Notebook chips that promote...
  25. Replies
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    If you use shared context make sure that the...

    If you use shared context make sure that the opengl objects are ready to be used before the other thread touches them! e.g. after loading an image with glTexImage2D call glFinish or use a fence...
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