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  1. Thanks, I read and think I understand the...

    Thanks, I read and think I understand the formulas that opengl uses, that was very helpful. I have also ensured that the render order of the layers is correct, but my question is now more general:
    ...
  2. I see.. yes this is exactly what I need, thanks!...

    I see.. yes this is exactly what I need, thanks!
    I suppose GL_FUNC_ADD would be appropriate for the first argument? If I use SRC_ALPHA and ONE_MINUS_SRC_ALPHA in the blending function?

    or...
  3. that is it, thanks! Actually: In my situation...

    that is it, thanks!

    Actually: In my situation ideal would be: overwrite alpha (with source alpha) if it's larger than the destination alpha, but I don't think that is an option in OpenGL, is it???...
  4. Blending on render to texture alpha problem

    Hi there,

    For a GUI system I render parts to a buffer/texture first (I call them a canvas), and then rendered the texture to the screen.

    For example

    -create buffer/texture
    -draw rectangle...
  5. Nice ideas :) I'll think I go for the first one.

    Nice ideas :) I'll think I go for the first one.
  6. Thanks, that was very clear. Is there a good way...

    Thanks, that was very clear.
    Is there a good way then to find out the distance perpendicular to the line segment of the fragment in the fragment shader? That seems neccesary for anti-aliassing or...
  7. rasterization and fragment coordinates for lines

    Hi there,

    I've been reading a bit about using lines in openGL, but it's not quite clear to me yet how they work in the fragment shader. Specifically I don't understand how the 3d fragment...
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    Yeah I get the idea :) I just looked in the...

    Yeah I get the idea :) I just looked in the manual / specifications, there are 107 instances of the word 'undefined' in there :)
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    I am testing with AMD radeon 6800 here. I guess...

    I am testing with AMD radeon 6800 here. I guess the tricky thing is that 'undefined' behavior does not produce any errors. So I was very surprised to see the terrain rendering in buffer 3, while I...
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    Thank you, it was indeed the alpha test!

    Thank you, it was indeed the alpha test!
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    to be more precise: this void main() {...

    to be more precise:

    this

    void main()
    {
    gl_FragData[0] = vec4(0,0,0,0.1);
    gl_FragData[1] = vec4(0,0,0,0);
    gl_FragData[2] = vec4(0,0,0,0);
    gl_FragData[3] = vec4(0,1,0,1);
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    if that is so, which I think would be very...

    if that is so, which I think would be very logical, then I don't understand this:

    In a shader to draw water:



    in the shade that renders the screen:
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    Hi arekkusu, thanks for your reply, most of it...

    Hi arekkusu,

    thanks for your reply, most of it makes sense now. Only thing is that don't understand why the alpha I write to buffer 0 effects the other buffers as well. How exactly does that...
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    selectively writing to buffers

    Hi,

    I ran into something weird, or something that I don't know how it works exactly.

    What I want to do when rendering to multiple targets is that I selectively write to certain color buffers...
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    thanks this is really helpful, will probably save...

    thanks this is really helpful, will probably save me some 'bug' tracking in the future too :)
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    hm hm trying to understand it here, most of it...

    hm hm trying to understand it here, most of it seems to make sense. But the part about adjecent pixels: the texture coordinates you talk about, are those the UV parameters on the primitive, or are...
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    I finally found it. In the 3D texture that I use...

    I finally found it. In the 3D texture that I use for fog, I set the min-filter to LINEAR (or NEAREST is also fine). It was default set to GL_LINEAR_MIPMAP_LINEAR by OpenSceneGraph.
    Can someone...
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    Exactly my thought, it almost HAS to do with...

    Exactly my thought, it almost HAS to do with something like that, because it happens at the edges of objects. Any other ideas or good ways to look into it are appriciated!
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    well it *should* be no aliassing. I use OSG for...

    well it *should* be no aliassing. I use OSG for rendering, and I read this in a OSG mailing list .
    And indeed when I add the texture as a render target there are arguments how many samples it should...
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    I use this: if (length(normal)==0) //sky {...

    I use this:


    if (length(normal)==0) //sky
    {
    gl_FragColor = vec4(0.90, 0.82, 0.47, 1);
    return;
    }

    But I noticed the strange effects are also on hilltops that are not on the edge with the...
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    The format I use is GL_RGB32F_ARB. I use OSG, so...

    The format I use is GL_RGB32F_ARB. I use OSG, so this is what I use:


    osg::TextureRectangle* positionsRect;
    positionsRect = new osg::TextureRectangle;
    positionsRect->setTextureSize(screenWidth,...
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    Yeah I'm doing that, but it's really puzzeling. I...

    Yeah I'm doing that, but it's really puzzeling. I tried finding the edge problem in one of the source buffers, but if I render those buffers as color values (making sure they are in range) then the...
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    Thanks for the info. I did make sure the textures...

    Thanks for the info. I did make sure the textures have the same size as the viewport/window so it should be a one on one pixel readout. But as the filtering of the buffers as textures for the quad is...
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    Yes I am, is that good or bad?

    Yes I am, is that good or bad?
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    Problem with 'edge' of hill and fog

    Hi I have a visual artefact in my scene that I don't quite understand. Some background information:

    In the pre-render I write to 3 buffers:
    -color
    -normal
    -position

    then in the render I...
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