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Type: Posts; User: Mike F

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  1. Replies
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    Re: Programmable GPU

    There's a method of giving everything a black outline (seen in Jet Set Radio) that would be a great application of vertex-shaders. It requires that each mesh be rendered twice - the second time, you...
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    Re: catch up with DirectX please!!!

    1) SGI has in fact released the entire source to their OpenGL sample implementation (plus GLU and GLUT
    2) Even if they hadn't, there's a 3rd-party open-source implementation of OpenGL available...
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    Re: Multitexturing without "Multitexturing"???

    2 passes needn't be twice as slow. If you let OpenGL know that your vertices haven't changed between the first and second passes, the cost of the second pass should be reduced somewhat.

    One way to...
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    Re: radix sort and blending

    Shellsort is also a good choice. It works well when the sort-order doesn't change much from frame-to-frame, which is the case in most 3D scenes since the camera typically moves only a short distance...
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    Re: make shadows part of of the API

    There's nothing stopping PowerVR from creating an OpenGL extension; that's the standard way of exposing any hardware-specific features.
    After seeing the modifier-volume shadows in Jet Set Radio, I'd...
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    Re: Depth-based blending

    I did a (very basic) GLUT demo of this a short while ago. I don't have a website to upload it to but I don't mind mailing it to anyone who's interested (mail me at mike.ferenduros@spiralhouse.co.uk)....
  7. Re: How to use GL functions outside of WM_PAINT message

    The GDI style of redrawing invalidated sub-areas of a window isn't really appropriate here. A more suitable way of doing things is:

    1) Do GetDC() and wglCreateContext() at startup and hang on to...
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    Re: cube vs dual paraboloid environment mapping

    I've not tried it myself.
    However, I have seen an extremely impressive D3D+GeForce demo of a Newton's cradle with all the balls correctly reflected in each other. In case you don't know it, a...
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    Re: cube vs dual paraboloid environment mapping

    You're right, cube-mapping is only practical with hardware-support. If you're trying to pick the most suitable technique, consider: Although dual-paraboloid envmaps aren't very intuitive, it's fairly...
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    Re: cube vs dual paraboloid environment mapping

    Cube envmaps actually make more efficient use of texture-memory than the other two techniques (which waste around 20% of a textures). A 128*128*6 cube-map compared with a 256*256 sphere-map will...
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    Re: trees and polygons and tnl

    There's an nVidia-specific extension that lets you put your verts into video-memory or AGP memory, I believe that will get you a speedup. The tradeoff is that you have to exercise a little care when...
  12. Thread: GL_S3_s3tc

    by Mike F
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    Re: GL_S3_s3tc

    No. In s3tc, the two colours in each block are always either 565 or 5551.

    Mike F
  13. Thread: GL_S3_s3tc

    by Mike F
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    Re: GL_S3_s3tc

    I'm using a GeForce, Win2k, latest drivers.
    I took a look at the s3tc spec and it doesn't say with how much precision the interpolated colours are calculated - if they're limited to 16bit colours...
  14. Thread: GL_S3_s3tc

    by Mike F
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    Re: GL_S3_s3tc

    I just tried switching S3TC on and although some textures look fine, some look absolutely terrible. The problem is not detail, it's that it looks like everything's been crunched down to 8bit colour....
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    Re: catch up with DirectX please!!!

    Take a look at the extensions registry at http://oss.sgi.com/projects/ogl-sample/registry/

    The extensions that provide major new functionality have recently come mainly from companies like...
  16. Re: Acessing to the textures data of the OpenGL driver

    glGet doesn't *have* to be slow on infreqently modified data (eg. textures) A driver could very easily detect that there are no pending modifications for a piece of data and not bother with the...
  17. Re: Acessing to the textures data of the OpenGL driver

    Although you can't *directly* access the textures, you can get a copy of a driver's texture with glGetTexImage.

    Since the drivers copy of a texture is in system-memory, querying it should be...
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    Re: Getting a device context for the back buffer

    That's a GeForce card, right? Try getting the latest nVidia reference drivers; I remember getting new (beta) GeForce drivers a while ago and getting a massive improvement with glReadPixels, so they...
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    Re: Getting a device context for the back buffer

    Yup, this sounds familiar. What video-cards are you using? Both glReadPixels and glDrawPixels are notoriously unoptimised on many consumer cards - it's a catch-22 situation where nobody uses them...
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    Re: Alternative to gluLookAt()

    If your cameras orientation is determined by pitch and yaw angles (quake-style) then you will be better off setting it up with 2 glRotate calls - one around the x axis, one around the up axis.
    ...
  21. Thread: Gamma corection

    by Mike F
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    Re: Gamma corection

    They're not part of OpenGL, but the Win32 functions in question are GetDeviceGammaRamp and SetDeviceGammaRamp.

    Mike F
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    Re: Getting a device context for the back buffer

    Mixing OpenGL and GDI calls is not generally a good idea.

    glDrawPixels blits an image into the buffer you specify with glDrawBuffer, and will cooperate with other OpenGL calls much better.

    Mike
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    Re: support for procedural textures !

    Definitely.
    Are there any fundamental reasons that glCopyTexSubImage2D can't be nearly as fast as true render-to-texture for smallish areas (say 128*128)? Would any driver guys care to enlighten us...
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    Re: Dynamic Lightmaps

    I believe Quake 3 uses a different approach for dynamic lights; it does an extra pass over the affected geometry, with a circular texture projected along the up axis, and the contribution of the spot...
  25. Re: GL_TEXTURE_ENV for special combining issues..

    The blend modes you mentioned aren't in the base OpenGL spec; try looking into the extension 'EXT_texture_env_combine', it does the stuff you mentioned and is supported on TNT.
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