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Type: Posts; User: carsten neumann

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  1. Hmm, I suggest to write a function that can draw...

    Hmm, I suggest to write a function that can draw a circle at a given location. Then call that function in a loop that goes through the list of vertices.

    If the above is not helpful, please...
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    That's what a cube looks like under orthographic...

    That's what a cube looks like under orthographic projection when looking straight at a single face.
  3. That is a good point, open source (e.g. ParaView)...

    That is a good point, open source (e.g. ParaView) and commercial (e.g. Amira) visualization software can do this too.
  4. OpenGL can not help with that, since it is purely...

    OpenGL can not help with that, since it is purely a rendering API. You need an algorithm that can extract an iso surface (or iso line in the 2D case) from a scalar field; one algorithm that can do...
  5. I'm not sure that it is the reason for the...

    I'm not sure that it is the reason for the problem, but when asking OpenGL to write data to client memory (like glReadPixels does) the GL_PACK_* (not GL_UNPACK_*) pixel store settings are relevant.
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    See glGetFloatv...

    See glGetFloatv with pname = GL_MODELVIEW_MATRIX or GL_PROJECTION_MATRIX.
  7. So the GPU still has to perform a matrix times...

    So the GPU still has to perform a matrix times vector multiplication for each vertex - in other words you've not saved any work on the GPU. You can keep things more flexible without any loss of...
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    No, I meant the transformations that formed the...

    No, I meant the transformations that formed the image (the camera applies some projection to get light onto the sensor), those are the ones you'd invert to go from a pixel position to a real world...
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    That could be a coincidence. Have you checked the...

    That could be a coincidence. Have you checked the compile and link info log (glGetShaderInfoLog, glGetProgramInfoLog) for helpful messages?

    I meant writing it like this:



    vec4 color =...
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    I believe this type of problem falls into the...

    I believe this type of problem falls into the field of "computer vision" and you may have better luck asking in a forum that is dedicated to that topic - for example you could try the OpenCV (a...
  11. Before OpenGL supported generic vertex attributes...

    Before OpenGL supported generic vertex attributes there was a fixed set of them that you could specify (position, normal, color, secondary color, N sets of texture coordinates) and each had a...
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    Note that the built-in output variable is called...

    Note that the built-in output variable is called gl_FragColor (with '_' after gl).

    If you suspect the GLSL compiler to muck up something, you could try to assign the shader output (either built-in...
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    Hmm, that is not a term I'm familiar with - that...

    Hmm, that is not a term I'm familiar with - that being said, I don't think it is related to your specific problem: If I'm reading it correctly 'enableNormalColor' is only used in the function...
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    For completeness/nitpicking (;)) sake:...

    For completeness/nitpicking (;)) sake: glGenBuffers does not create buffer objects, it only reserves names for them. The actual object (i.e. the thing where the implementation stores state) is...
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    My comment was targeted at these lines that you...

    My comment was targeted at these lines that you posted:


    glLightfv(GL_LIGHT0, GL_DIFFUSE, lightColour0);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, lightPos0);


    The variable names suggest you want to...
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    If you want to set a light's position (or...

    If you want to set a light's position (or direction for a directional light source) you need to pass GL_POSITION as second argument to glLightfv.
  17. There is one non-indexed bind point and a number...

    There is one non-indexed bind point and a number of indexed bind points. The non-indexed bind point allows you to manipulate the bound buffer in various ways, for example you can map its data storage...
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    On nvidia hardware there are the two extensions...

    On nvidia hardware there are the two extensions WGL_NV_DX_interop and WGL_NV_DX_interop2 - I don't know enough about DirectX to say if there are options for other vendors as well.
  19. In code like: ...

    In code like:


    glBindBuffer(GL_UNIFORM_BUFFER, uniformBufferId);
    glBindBufferBase(GL_UNIFORM_BUFFER, bindingPoint, uniformBufferId );


    the glBindBuffer is not needed,...
  20. If you are doing nothing at all in...

    If you are doing nothing at all in glfwSetWindowSizeCallback, you are missing a call to glViewport to inform OpenGL how to transform normalized device coordinates to window coordinates - for the...
  21. I'm a bit confused, which vertex shader are you...

    I'm a bit confused, which vertex shader are you referring to?

    In any case I doubt the glut text (stroke or bitmap) functions work in a core context - in fact since you are using freeglut you can...
  22. IntPtr ptr1 = GCHandle.Alloc(modelData,...

    IntPtr ptr1 = GCHandle.Alloc(modelData, GCHandleType.Pinned).AddrOfPinnedObject();


    vertices instead of modelData?
  23. Ok, I see, thanks. Unfortunately I don't really...

    Ok, I see, thanks. Unfortunately I don't really have a good idea what is wrong with the points rendering, can you post a screenshot? Also, you should still clear the depth buffer at the beginning of...
  24. Please use around source code, otherwise the...

    Please use
    around source code, otherwise the formatting/indention is lost making it unnecessary hard to read.

    So does this actually still render the cube? When I was saying GL_TRIANGLES I...
  25. That should not happen if you first rendered the...

    That should not happen if you first rendered the faces of the cube as GL_TRIANGLES. Are you perhaps clearing the depth buffer between rendering the faces and the points?
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