Part of the Khronos Group
OpenGL.org

The Industry's Foundation for High Performance Graphics

from games to virtual reality, mobile phones to supercomputers

Page 2 of 5 FirstFirst 1234 ... LastLast
Results 11 to 20 of 45

Thread: OpenGL should provide direct font support

  1. #11
    Senior Member OpenGL Pro
    Join Date
    Apr 2010
    Location
    Germany
    Posts
    1,128
    Have you ever done graphics programming? Do you know the mathematical implications of the clipping planes? Any idea?

  2. #12
    Advanced Member Frequent Contributor
    Join Date
    Apr 2009
    Posts
    600
    Quote Originally Posted by LuisAK
    here two other intellectual limits are reached by OpenGL:
    http://www.naturewizard.com/Tutorial...s/image005.jpg
    The near clipping plane, and the far clipping plane.
    How can I tell those guys that these limits are not necessary ?

    Therefore here are my suggestions for the next release of OpenGL :
    - native font support
    - no near clipping plane
    - no far clipping plane
    - better polygonal functions

    This has got to be a joke, right? The near and far clipping plane are only _concepts_ and not even a part of the OpenGL core profile specifications. I strongly urge you to read the specification and learn what are normalized device coordinates. Once you kind of understand what those are, then read what a projection matrix is, and then about various standard projection matrices.

    Going further, the "native font support", did you even read what people wrote? OpenGL is a specification meant to exist on many platforms: MS-Windows, Mac OS-X, Unix .. and even to a lesser extent mobile platforms in some cases [at the very least OpenGL ES, but some mobile do OpenGL as well]. A specification needs to specify what to do with the files, what is rendered, etc in a way possible on all these platforms. On the subject of font rendering, hardware font rendering is a highly non-trivial action. Indeed, once hinting gets into play, then without truly extraordinary and heroic efforts one must use the CPU to render a glyph... in truth, I think even with such efforts, once hinting is required, then one must still use a CPU.

    As for "better polygonal functions", do you mean triangulation or arbitrary polygons? If you want that, then use GLU to freaking do it for you.. or rip it out of Regal and call it a day.

  3. #13
    Member Regular Contributor Nowhere-01's Avatar
    Join Date
    Feb 2011
    Location
    Novosibirsk
    Posts
    251
    or you could just ignore him and ask moderator to lock the topic leaving only explanation why initial idea is stupid. that guy obviously have little or nothing to do with graphics programming and keep's posting that crap out of boredom, cause he gets a lot of attention for his extreme ignorance. he obviously didn't read your messages.

    i suggest to make a sticky thread for this forum, containing Frequent Suggestions in FAQ format, containing some popular suggestions with short explanations why they are not or shouldn't be implemented.

  4. #14
    Intern Newbie
    Join Date
    Dec 2012
    Posts
    43
    http://www.opengl.org/sdk/docs/man2/...erspective.xml

    gluPerspective — set up a perspective projection matrix C Specification
    void gluPerspective( GLdouble fovy,
    GLdouble aspect,
    GLdouble zNear,
    GLdouble zFar);

    Parameters
    fovy Specifies the field of view angle, in degrees, in the y direction.

    aspect Specifies the aspect ratio that determines the field of view in the x direction. The aspect ratio is the ratio of x (width) to y (height).

    zNear Specifies the distance from the viewer to the near clipping plane (always positive).

    zFar Specifies the distance from the viewer to the far clipping plane (always positive).
    ---------------------------------------------------------------------------------------------------

    if you have a look at the Parameters zNear and zFar, these are unnecessary restrictions !

    ---------------------------------------------------------------------------------------------------
    I know, what I´m talking about I´ve been building such a system
    Click image for larger version. 

Name:	UPF1S2-2-ArticulatedRobot.jpg 
Views:	138 
Size:	32.7 KB 
ID:	987
    and a global player is holding two patents on my name.
    ---------------------------------------------------------------------------------------------------
    the topic is: suggestions for the next release of OpenGL
    an this is my opinion

    best regards
    Luis

  5. #15
    Intern Newbie
    Join Date
    Dec 2012
    Posts
    43
    http://www.opengl.org/archives/resou...pping.htm#0050
    > When I move the viewpoint close to an object, it starts to disappear. How can I disable OpenGL's zNear clipping plane?
    > You can't. If you think about it, it makes sense: What if the viewpoint is in the middle of a scene? Certainly some geometry is behind the viewer and needs to
    > be clipped. Rendering it will produce undesirable results.

    > For correct perspective and depth buffer calculations to occur, setting the zNear clipping plane to 0.0 is also not an option.
    > The zNear clipping plane must be set at a positive (nonzero) distance in front of the eye.

    > To avoid the clipping artifacts that can otherwise occur, an application must track the viewpoint location within the scene,
    > and ensure it doesn't get too close to any geometry. You can usually do this with a simple form of collision detection.
    > This FAQ contains more information on collision detection with OpenGL. .........

    what a nonsensical restriction

    best regards
    Luis

  6. #16
    Intern Newbie
    Join Date
    Dec 2012
    Posts
    43
    http://www.opengl.org/archives/resou...pping.htm#0050

    "setting the zNear clipping plane to 0.0 is also not an option. The zNear clipping plane must be set at a positive (nonzero) distance in front of the eye."
    --------------------------------------------
    what a nonsensical restriction.
    --------------------------------------------

  7. #17
    Member Regular Contributor malexander's Avatar
    Join Date
    Aug 2009
    Location
    Ontario
    Posts
    324
    It's not at all nonsensical. In a perspective projection, the X and Y coordinates are divided by the distance from the camera, Z. If Z is zero, you'll get divisions by zero. Or, in practical terms, an object zero units from the camera will appear infinitely large. To avoid this, the near clipping plane is nudged slightly out from zero.

    It would be nice, in some cases, to have more precision available so that the far:near ratio can be made more than 1,000,000:1 without significant z-fighting. This is a hardware restriction, however, and not something imposed by OpenGL (or DirectX, for that matter). When a 64b z-buffer makes its debut, I suppose you could set the far plane to some huge value and have a nearly-infinite frustum. Until then, you pretty much have to work with the hardware available, and the best it can currently do is a 32b FP z-buffer in the range [0..1].

  8. #18
    Junior Member Regular Contributor
    Join Date
    Dec 2009
    Posts
    212
    Actually OpenGL can deal with a literally infinite distant far plane already, it's just not possible to set up this projection via GLU (but then GLU isn't part of OpenGL), it doesn't even have a big impact on Z-buffer precision. Most of the Z-buffer range is used for the distances close to the near plane.

    Moving the near clipping plane onto the camera (which happens when zNear = 0.0) will cause the near plane to be shifted to infinity in clip space along with the camera, which will cause a lot of precision issues (24, 32 or even 64 bit integers are a bit too small to store infinity), but for all practical purposes you can get the same effects as zNear = 0.0 by just disabling depth clamp.

  9. #19
    Senior Member OpenGL Guru
    Join Date
    May 2009
    Posts
    4,948
    by just disabling depth clamp.
    You mean enabling depth clamp. Enabling depth clamp disables near clipping.

  10. #20
    Junior Member Regular Contributor
    Join Date
    Dec 2009
    Posts
    212
    Alfonse is of course right, I meant enabling depth clamp.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •