Part of the Khronos Group
OpenGL.org

The Industry's Foundation for High Performance Graphics

from games to virtual reality, mobile phones to supercomputers

Search:

Type: Posts; User: GClements

Page 1 of 20 1 2 3 4

Search: Search took 0.05 seconds.

  1. Replies
    1
    Views
    17

    OpenGL's "default" layout (i.e. with the...

    OpenGL's "default" layout (i.e. with the transpose parameter set to GL_FALSE) is column-major, i.e.


    0 4 8 12
    1 5 9 13
    2 6 10 14
    3 7 11 15

    It's impossible to say for sure which...
  2. Replies
    5
    Views
    124

    We can't see any such thing, as we don't know...

    We can't see any such thing, as we don't know what the projection and model-view matrices contain. You show the quad's Z coordinate in object space (i.e. the values passed to glVertex()) but the...
  3. Yes. Well, assuming that nelements isn't zero (it...

    Yes. Well, assuming that nelements isn't zero (it shouldn't be, but then passing a null pointer for the attribute list is supposed to work).
  4. Have you tried passing an empty attribute list...

    Have you tried passing an empty attribute list (i.e. where the first element is None)?

    That should have the same effect as passing a null pointer, i.e. returning all configurations.
  5. Replies
    3
    Views
    109

    The first set of calls specifies the data for...

    The first set of calls specifies the data for attribute zero. The second set specifies the data for the Colour_In attribute. Your shader then specifies (via "layout(location=0)")that Colour_In is...
  6. Has FBO been allocated (i.e. "FBO = new int[1]")?

    Has FBO been allocated (i.e. "FBO = new int[1]")?
  7. I suspect that 150 point lights is exceeding the...

    I suspect that 150 point lights is exceeding the size of the default uniform block. Try reducing that number.

    The errors from the compiler are referring to offsets in the compiled code, not line...
  8. Replies
    6
    Views
    266

    I would assume that exporting with flat shading...

    I would assume that exporting with flat shading will give each face a distinct set of vertices using the face normal, rather than vertices being shared between adjacent faces.
  9. You're supposed to use glXGetProcAddress() (or a...

    You're supposed to use glXGetProcAddress() (or a higher-level library such as GLEW) to obtain pointers to those functions, rather than linking to them directly.

    That avoids the need for the client...
  10. Any call to glVertexAttribPointer() or similar...

    Any call to glVertexAttribPointer() or similar will store a reference to the buffer which is currently bound to the GL_ARRAY_BUFFER target in the VAO, along with the parameters to that call.

    You...
  11. Classical 2D graphics algorithms in the style of...

    Classical 2D graphics algorithms in the style of graphics.h have little in common with OpenGL.

    Most modern 2D graphics APIs (the model used by PostScript, PDF, SVG, OpenVG, cairo, HTML 5 canvas...
  12. Replies
    6
    Views
    266

    You need to normalise v_LightVec and v_HalfVec in...

    You need to normalise v_LightVec and v_HalfVec in the fragment shader. The result of interpolating between two unit-length vectors is a vector of less than unit length.
  13. Replies
    6
    Views
    266

    The reason is almost certainly that the vectors...

    The reason is almost certainly that the vectors forming your tangent space (tangent, bitangent, normal) are discontinuous at the edges of faces.

    Either you aren't interpolating them correctly (or...
  14. Thread: Porting Help

    by GClements
    Replies
    7
    Views
    259

    In which case,consider porting the application to...

    In which case,consider porting the application to use a different API, e.g. OpenVG or cairo or ... whatever the device supports natively.
  15. Thread: Porting Help

    by GClements
    Replies
    7
    Views
    259

    Mesa (http://www.mesa3d.org/) provides a software...

    Mesa provides a software implementation of OpenGL, including OpenGL ES 2.0. It uses LLVM to compile GLSL shaders to native machine code. At one point it included a DirectFB driver, but that has since...
  16. All kinds of things might cause them. But...

    All kinds of things might cause them. But probably the biggest single cause of problems with depth precision is using too small a value for the near distance.

    As a rough guide, the portion of the...
  17. Replies
    2
    Views
    170

    It's most likely a sprite with partial alpha....

    It's most likely a sprite with partial alpha. Possibly using additive blending (as the order doesn't matter if multiple effects overlap).
  18. Replies
    3
    Views
    164

    If the fragment shader uses...

    If the fragment shader uses layout(early_fragment_tests) (originally from ARB_shader_image_load_store), the stencil and depth tests are performed prior to executing the fragment shader, and stencil...
  19. Replies
    3
    Views
    164

    Where? That seems backwards. ...

    Where? That seems backwards.

    layout(depth_less) tells the implementation to assume that the value written to gl_FragDepth will be less than or equal to the depth value obtained by interpolation...
  20. Yes, exactly.

    Yes, exactly.
  21. Replies
    2
    Views
    179

    After converting your code to use GLUT rather...

    After converting your code to use GLUT rather than PyGame, it works on my system insofar as the triangle is rendered, but in black.

    To get the correct colour, I needed to add the following to the...
  22. Replies
    4
    Views
    214

    Use pre-multiplied alpha. Conversion from...

    Use pre-multiplied alpha.

    Conversion from un-multiplied alpha to pre-multiplied alpha converts (r,g,b,a) to (r*a,g*a,b*a,a). This needs to be done to the image data before it's uploaded to the...
  23. You might want to consider using...

    You might want to consider using std::unordered_map (or std::map if that's not available) to hold the mapping between position/texcoord/normal triples and unique vertex indices. That has O(1) (or...
  24. Replies
    2
    Views
    143

    glMapBuffer() isn't mlock(). There are several...

    glMapBuffer() isn't mlock().

    There are several types of "resources" involved here: video memory, (physical) system memory, virtual memory (physical memory plus swap) and address space.

    Address...
  25. Replies
    4
    Views
    182

    To tell the implementation you changed a...

    To tell the implementation you changed a particular portion of the buffer.

    If the buffer is mapped with GL_MAP_FLUSH_EXPLICIT_BIT, glUnmapBuffer() will not automatically flush the entire mapped...
Results 1 to 25 of 500
Page 1 of 20 1 2 3 4