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Thread: The ARB announced OpenGL 3.0 and GLSL 1.30 today

  1. #611
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    Re: The ARB announced OpenGL 3.0 and GLSL 1.30 tod

    Quote Originally Posted by Eric Lengyel
    1) Quads. I use these a lot for particle systems, fire, and other special effects where you end up rendering a bunch of disjoint quads that have their vertex positions recalculated every frame. It just makes sense to dump the four corners of each quad into a buffer and let the hardware render them as quads. Quads are supported in hardware by all Nvidia chips and all recent ATI chips. If quads go away, then I have to either (a) dump six vertices into the vertex buffer for each quad instead of four, or (b) construct an index buffer in addition to the vertex buffer that wasn't necessary before. In both cases, we lose speed and increase memory requirements.
    Absolutely agree!
    Quads are very useful feature for things like particles or many billboarded distant objects (trees) etc.
    Also useful for drawing of text (quad per letter) tho for that one can also use point sprites if the text is in screen space(which is most often the case)
    You can't often replace quads with point sprites because the latter can only be screen-space axis-aligned squares (if you use bigger sprite and cut the unneeded parts with texkill, you waste gpu time and/or fill rate)

    They are far more useful than triangle fans for example yet the last aren't deprecated but the quads are.
    This was one of the nice OpenGL features that contributed to it's charm in contrast to direct 3d

    About the quad_strip and polygon, they are unneeded indeed: the first is a triangle strip with different vertex order and the second is triangle fan
    But i'm so unhappy about the quads

  2. #612
    Senior Member OpenGL Guru
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    Re: The ARB announced OpenGL 3.0 and GLSL 1.30 tod

    The ARB_fbo extension does have some very useful enhancements. Nice to see that the limitation, that all render-targets need to have the same sizes (width, height) and format, will be lifted.

    Jan.
    GLIM - Immediate Mode Emulation for GL3

  3. #613
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    Re: The ARB announced OpenGL 3.0 and GLSL 1.30 tod

    IIRC the same-width/height/stride limitations were based on hardware, so that extension won't be exported on all OpenGL hardware, just the ones that do not have that limitation. Roughly speaking, parts which can run DirectX 9.0 are in that category.

  4. #614
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    Re: The ARB announced OpenGL 3.0 and GLSL 1.30 tod

    Probably the biggest difference the lack of quads will make is that when I am rendering terrain, the indice data will be 50% larger. Not a huge deal, but it's something to think about.

    As pointed out, particles become a little awkward. Not a huge deal, just a little annoying.

  5. #615
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    Re: The ARB announced OpenGL 3.0 and GLSL 1.30 tod

    ...That means you're literally using GL_QUADS. 6 indices instead of 4. But why not use a triangle strip?
    while(1){keyboardsolo(FORTE, BPM_190);}

  6. #616
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    Re: The ARB announced OpenGL 3.0 and GLSL 1.30 tod

    Depending on what LOD-schemes you use, you might very well not be able to render your terrain with triangle-strips, at least not without nVidias (proprietary) restart-extension.
    GLIM - Immediate Mode Emulation for GL3

  7. #617
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    Re: The ARB announced OpenGL 3.0 and GLSL 1.30 tod

    I'd actually like to see GL_POLYGONS implemented:

    Each polygon would start with the number of indices, followed by that many indices. So you could mix triangles, quads, pentagons, whatever. It would be useful for CSG geometry.

  8. #618
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    Re: The ARB announced OpenGL 3.0 and GLSL 1.30 tod

    Quote Originally Posted by Leadwerks
    I'd actually like to see GL_POLYGONS implemented
    While I can sympathize with this whish, I'd personally oppose it if the issue was raised. For one thing it would open a can of worms in areas such as "interpolate between n vertices", "what if the vertices describe a concave surface" and "what if these point's are not on a plane?" - not to mention different implementations might have different optimizations or calculations, making one impl. see an n-polygon as planar, while another not.

    I think you see the problem.

    As for CSG, that's outside the scope of OpenGL (as I'm sure you know ).

  9. #619
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    Re: The ARB announced OpenGL 3.0 and GLSL 1.30 tod

    It would expect a concave coplanar surface, just like GL_POLYGON or GL_QUADS does. Really it is just a compact way of drawing triangles. But I agree, it's not important, and if I can just have triangles work on all targetted hardware without any bugs, I would be happy.

  10. #620
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    Re: The ARB announced OpenGL 3.0 and GLSL 1.30 today

    OpenGL 3.0 sucks
    It just wasted our time

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