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  1. The draw buffer state and write masks prevent the...

    The draw buffer state and write masks prevent the texture from being modified, but the pixels are still deemed to have been modified so far as the memory model is concerned. The implementation is...
  2. Unspecified. In general, anything which would...

    Unspecified. In general, anything which would have no observable side-effects (other than performance) is unspecified.
  3. This is normally done by the toolkit (GLUT, GLFW,...

    This is normally done by the toolkit (GLUT, GLFW, Qt, etc). Most toolkits automatically create one or more contexts whenever you create a window and destroy them when the window is destroyed.

    If...
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    And also dependent upon the number of variables...

    And also dependent upon the number of variables output from the vertex shader (the vertex cache is sized in bytes, not vertices). There's no mechanism to query the cache size directly, although it...
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    OpenGL 3.0 deprecated many features, e.g. the...

    OpenGL 3.0 deprecated many features, e.g. the fixed-function pipeline, glBegin/glEnd, etc. 3.1 removed these features altogether. 3.2 introduced two distinct profiles: the core profile (which doesn't...
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    If you want to translate a 2D window position to...

    If you want to translate a 2D window position to a 3D position in eye space or object space, you need to read the corresponding pixel from the depth buffer, then apply the inverse projection...
  7. The major "milestones" in OpenGL are: 2.0...

    The major "milestones" in OpenGL are:


    2.0 adds shaders as an alternative to the fixed-function pipeline. This is the minimum version which supports "modern" OpenGL.
    3.0 adds VAOs, and...
  8. For the benefit of anyone encountering this...

    For the benefit of anyone encountering this thread via a search ...



    This information isn't made available automatically. You could have 3 flat-qualified attributes set by a geometry shader....
  9. You just have ;)

    You just have ;)
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    Maybe, depending upon the number of vertices....

    Maybe, depending upon the number of vertices. Also, it would use 4 attribute slots, as a mat4 attribute is effectively 4 vec4 attributes.

    Typically, there are constraints upon the transformation...
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    Here's a diagram to explain the coordinate...

    Here's a diagram to explain the coordinate system:
    2510

    If you want polylines with rounded or mitred joins, you have to calculate the distance along the edge of the stroke. If you just want caps,...
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    Add appropriate attributes to each vertex,...

    Add appropriate attributes to each vertex, containing "line space" coordinates. These will be interpolated during rasterisation, so the fragment shader knows the fragment's location relative to the...
  13. That's because you're applying the offset after...

    That's because you're applying the offset after the coordinates have been transformed to clip space. If you want the offset to be applied in object space:


    gl_Position = Projection * View *...
  14. You're correct in your interpretation of the...

    You're correct in your interpretation of the arguments.

    However, the function specifically clamps the point to the endpoints, i.e. it returns the closest point on the line segment rather than on...
  15. Your geometry shader is emitting four identical...

    Your geometry shader is emitting four identical points, so you shouldn't be seeing anything.

    To get quads which are aligned in model space, you should be adding offsets after transformation by the...
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    Are you converting the lines to triangles (either...

    Are you converting the lines to triangles (either in client code or a geometry shader), or just using glLineWidth() to render thick lines?

    Either way, you need to set appropriate attributes. One...
  17. Use the GLM_GTX_closest_point...

    Use the GLM_GTX_closest_point module.
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    All common GUI toolkits work like this. If you...

    All common GUI toolkits work like this. If you want to use multiple threads, you have to do this yourself.


    None of the common toolkits do this. Certainly, it doesn't apply to Xt, GTK+, Qt,...
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    The denominator is the product of the lengths,...

    The denominator is the product of the lengths, |n|*|a|. The arguments to the sqrt()s cannot be negative (they're the sum of squares, and squares can't be negative), and the result of sqrt() is always...
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    Note that the above is just an inefficient way of...

    Note that the above is just an inefficient way of writing

    m_parent->WorldTransform() * Transform * Animation

    For any matrices A, B: (AB)-1=B-1A-1.


    Animation = inverse(Transform) *...
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    This forum doesn't have a concept of "closing"...

    This forum doesn't have a concept of "closing" threads. Once a thread has been created, it usually remains open forever. Occasionally people post to threads which have been dormant for years (usually...
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    This is true for almost any application which...

    This is true for almost any application which doesn't explicitly use multi-threading. All of the common GUI toolkits invoke event callbacks in the main thread.
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    x = glm::vec3(1,4,-1);

    x = glm::vec3(1,4,-1);
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    Yes. Although given mhagain's comments about...

    Yes. Although given mhagain's comments about performance on Windows, you probably wouldn't want to be changing contexts on a per-frame basis with real-time animation.

    I've used that approach to...
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    If a texture doesn't have all of the mipmap...

    If a texture doesn't have all of the mipmap levels defined, it's necessary for the minification filter to be one which doesn't use mipmaps (i.e. GL_NEAREST or GL_LINEAR). This is true regardless of...
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