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Type: Posts; User: GClements

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  1. Replies
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    All OpenGL image formats use a whole number of...

    All OpenGL image formats use a whole number of bytes for each pixel, so the smallest framebuffer size will be 64 kiB.

    After rendering you can either use the CPU or a compute shader or fragment...
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    You're still confused. Do you want it to treat...

    You're still confused. Do you want it to treat the input as a colour or as a triple of integers? A colour is actually a triple of "reals" in the range 0..1, although a common representation is as...
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    It doesn't change the orientation. It does change...

    It doesn't change the orientation. It does change the origin. The result is equivalent to glTranslatef(0,0,-2).

    Note that your projection matrix is set with gluOrtho2D and your vertices with...
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    There's no point if you're using shaders. I...

    There's no point if you're using shaders.

    I only mentioned it in case someone using legacy OpenGL has the same problem and stumbles across this thread.
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    The texture() function performs texture lookups...

    The texture() function performs texture lookups using normalised texture coordinates (in the range 0..1), not texel indices. Either divide the offsets by textureSize(video) or change them to ivec2...
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    This appears to be a re-run of this thread...

    This appears to be a re-run of this thread.
  7. It looks like differences in winding order...

    It looks like differences in winding order (clockwise versus counter-clockwise), back-face culling, or Z direction (positive Z into screen versus out of screen).
  8. If you want the cube to rotate about its centre,...

    If you want the cube to rotate about its centre, the cube's origin should probably be its centre rather than a corner.

    Having said that, you can rotate about an arbitrary point (cx,cy,cz) by...
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    The texture origin is at the corner of the first...

    The texture origin is at the corner of the first texel in the data passed to glTexImage. If the first texel is the top-left texel, then texture coordinates of (0,0) correspond to the top-left corner...
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    I'm not familiar with Delphi, but from a brief...

    I'm not familiar with Delphi, but from a brief look at the documentation, you can get the underlying bitmap handle (HBITMAP) via the Handle member, on which you can call the GetDIBits() GDI function....
  11. Given the small amounts of data involved, it...

    Given the small amounts of data involved, it wouldn't be a disaster if you duplicated the position data. I.e. store each object's position in the object itself, then before rendering iterate over the...
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    Yes. fovy is the angle between the top and bottom...

    Yes. fovy is the angle between the top and bottom edges of the view frustum (the angle between either edge and the centre is fovy/2).
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    The original was released at a time when few PCs...

    The original was released at a time when few PCs had 3D-accelerated video hardware, so I presume that you're referring to the "remastered" version which has just been released.

    A quick web search...
  14. Well, you'd probably perform the calculations...

    Well, you'd probably perform the calculations as-needed, rather than processing all vertices and faces for each smoothing group. A given face only has a single normal, a vertex has one normal for...
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    Most image formats can't handle GL_RGBA32F (BMP...

    Most image formats can't handle GL_RGBA32F (BMP certainly can't). TIFF probably can (it tries to support everything), but I doubt that much software which "supports TIFF" can handle it.

    Most...
  16. IMHO, it's better to start with legacy OpenGL...

    IMHO, it's better to start with legacy OpenGL until you have some familiarity with the basic concepts, then switch.

    If you try to use modern OpenGL from the outset, you have to learn several...
  17. Aside from the buffer-management issues, you can...

    Aside from the buffer-management issues, you can halve the memory usage by using 16-bit fixed-point values instead of 32-bit floats.

    Another possibility for drawing axis-aligned rectangles is to...
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    Pango includes functions to render the layouts it...

    Pango includes functions to render the layouts it creates, using Win32, FreeType, Xft, CoreText, or cairo.
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    In the general case, use Pango or native OS...

    In the general case, use Pango or native OS functions to render complete strings into a bitmap which is then uploaded to a texture.

    The glCallLists() approach can only work with "linear" scripts,...
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    IOW, you want a larger view angle. It takes...

    IOW, you want a larger view angle.


    It takes an aspect ratio and a view angle.


    glViewport() sets the portion of the window which is mapped to X and Y coordinates of the clip space. Enlarging...
  21. Thread: hole filling

    by GClements
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    No. OpenGL is a rendering API, not a...

    No.

    OpenGL is a rendering API, not a modelling/geometry library.
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    If you look at the sample code, the condition...

    If you look at the sample code, the condition expression is uniform (i.e. involves only uniforms and constants), so the value will be the same for all fragments within a group. Modern hardware will...
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    My first guess would be issues related to the...

    My first guess would be issues related to the precision of the trigonometric functions.

    You could try reformulating your equations to avoid some of these. A brief look at your code shows that most...
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    You aren't going to see implementations duplicate...

    You aren't going to see implementations duplicate large amounts of "stable" data, particularly in VRAM.

    What can realistically happen is that updating data may result in both the old and new...
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    No. You're assuming that the contours are...

    No.


    You're assuming that the contours are convex, but there's no reason to believe that assumption is valid.
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