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Type: Posts; User: mhagain

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  1. With GL 1.4 or the GL_ARB_texture_env_combine...

    With GL 1.4 or the GL_ARB_texture_env_combine extension (there's also an _EXT version but I'm ignoring that because _ARB is ubiquitous) you can set an RGB scaling factor of 1, 2 or 4 which is applied...
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    That's where the scissor test comes in - glClear...

    That's where the scissor test comes in - glClear obeys the current scissor test options, so for your initial example:
    You can use:
    glEnable (GL_SCISSOR_TEST);
    glScissor (1000, 800, 4, 4);...
  3. This is more of a theoretical problem than a...

    This is more of a theoretical problem than a practical one. In reality you're going to find that with n features you're not going to need every single combination, and that many combinations don't...
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    Try first calling glClearDepth to select the...

    Try first calling glClearDepth to select the value to clear it to.

    Then enable scissor test and set a scissor rect to the area to be cleared.

    Finally glClear (GL_DEPTH_BUFFER_BIT), and when...
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    But we still don't know what your problem is. ...

    But we still don't know what your problem is.

    OK, let me try to put this as clear as I can. You say you want to clear a polygon on the screen, but you haven't said why. You haven't told us what...
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    Actually if you look at the documentatio for it:...

    Actually if you look at the documentatio for it: https://www.opengl.org/sdk/docs/man2/xhtml/glOrtho.xml you'll see that the generated matrix uses division by "right - left", "top - bottom" and "far -...
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    At this stage you need to be more specific about...

    At this stage you need to be more specific about exactly what it is you're trying to do. Don't even focus on clearing stuff, forget about glScissor, forget about how you'd like to solve the problem,...
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    This is something that comes up regularly enough,...

    This is something that comes up regularly enough, although it's been a while since I've seen it.

    Typically somebody only wants to change a small part of the scene (maybe they're implementing an...
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    glOrtho ( Left , Left , 10.0 , 10.0 , ..... ...

    glOrtho ( Left , Left , 10.0 , 10.0 , .....
    This is almost certainly not what you want; see https://www.opengl.org/sdk/docs/man2/xhtml/glOrtho.xml
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    They look fine; I wouldn't worry about...

    They look fine; I wouldn't worry about deprecation in this case since glTexGen itself is also deprecated, so at least you've satisfied the condition that your calculations are going to be consistent.
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    You can use the GL specification to source the...

    You can use the GL specification to source the formulas used for texcoord auto-generation and recalculate them yourself from the retrieved vertex position value.
  12. Unfortunately OpenGL complicates things a little...

    Unfortunately OpenGL complicates things a little because the internalFormat you request is not necessarily what the driver itself will use.

    The classic example of this is that a GL_RGB...
  13. The driver will convert the format during the...

    The driver will convert the format during the transfer operation. Which could be slow.
  14. They're just different names for the same thing....

    They're just different names for the same thing.

    Modelling programs and D3D tend to use (u, v) whereas OpenGL tends to use (s, t) but it's just a naming convention. You could name them (x, y) or...
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    It's not necessarily going to perform faster if...

    It's not necessarily going to perform faster if you selectively update individual vector components like this. It may even perform slower.

    GPUs like reading each vertex as a contiguous chunk of...
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    This has absolutely nothing to do with OpenGL.

    This has absolutely nothing to do with OpenGL.
  17. // Stick the data for the vertices and indices in...

    // Stick the data for the vertices and indices in their respective buffers
    glNamedBufferDataEXT(m_vertexBuffer, sizeof(vertices[0]) * vertices.size(), &vertices[0], GL_STATIC_DRAW);...
  18. Are you creating the buffer using glGenBuffers or...

    Are you creating the buffer using glGenBuffers or glCreateBuffers? Note that in the former case (i.e with glGenBuffers) the buffer object does not exist; all that glGenBuffers gives you is a name,...
  19. Thread: Regex

    by mhagain
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    This is absolutely nothing to do with OpenGL.

    This is absolutely nothing to do with OpenGL.
  20. For fully dynamic data (i.e that changes each...

    For fully dynamic data (i.e that changes each time it's used) immediate mode can be just as fast as using buffer objects, but this depends on the type of objects you're drawing and other factors.
    ...
  21. I would suspect that the Mesa driver only...

    I would suspect that the Mesa driver only supports GL3.3 but the OP's hardware is actually capable of GL 4.x, hence asking if a Windows VM would be able to access that capability. I've no experience...
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    Why do you want to avoid using glViewport? ...

    Why do you want to avoid using glViewport? glViewport is much more efficient than multiple contexts for this kind of division of the scene.

    I'm not personally familiar with qt but I am aware that...
  23. Hmmm, my reading of the spec is that "uniform...

    Hmmm, my reading of the spec is that "uniform flow control" essentially equates to "no flow control at all", but the statement that "This is similarly defined for other shader stages, based on the...
  24. That's not what non-uniform flow control means.

    That's not what non-uniform flow control means.
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    And it can continue to serve you well for the...

    And it can continue to serve you well for the next few decades if you wish. Here's a thing that people always seem to get confused about during this kind of evolution: this is not a zero-sum game. ...
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