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Type: Posts; User: JRGlide

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    I just wanted to do a followup in case this might...

    I just wanted to do a followup in case this might be useful to someone else. In the original question I stated that I was trying to do rendering in software but let OpenGL do the heavy lifting for...
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    Thank you, mhagain. It was starting to appear...

    Thank you, mhagain. It was starting to appear that might be the case. You have to admit, it was a cool idea, though...
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    Pixel spacing in Ortho view

    How does Open GL set the pixel spacing in Orthographic view? For example, let's say I am rendering at 2x2 rows and columns and the extents are -1 to +1. To me the (x,y) render coordinates should be...
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    Determing facet winding

    We normally use clockwise windings for our facet models. However, we have some models that have a mixture of CW and CCW facets so that the backward facets appear dark when displayed in OpenGL.

    I...
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    Re: Obtaining z and angle of incidence

    Oops! I thought you said port it to OpenGL, but you said OpenCL. One concern I have about using the GPU is that I've heard that it's tight on memory. A scene with 3 million facets requires 108 Meg...
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    Re: Obtaining z and angle of incidence

    I have a software version that works. The trouble is that it is slow. I have a scene with over three million facets. To do a 1024x1024 rendering takes 90 seconds, whereas GL does it in an instant....
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    Obtaining z and angle of incidence

    I have a project where I need to render a huge amount of data that could takes weeks of processing. I got the idea of letting OpenGL do the heavy lifting for me to speed things up. The problem is...
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    Re: Obtaining angle of incidence

    Thank you, tksuoran. The first option sounds like my best bet. Plus this would solve another problem, which leads to a second question.

    I was planning on using glReadPixels to read the depth...
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    Obtaining angle of incidence

    Is there a way to determine the angle of incidence of a facet from the frame buffer?

    I know how to use glReadPixels using GL_DEPTH_COMPONENT and then gluUnProject to get the 3D location. Is there...
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    Re: Grid following contour lines

    Thank you for your help. I will try both methods and see how they look.
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    Grid following contour lines

    I have a program that allows the user to build scenes and there is an option to display grid lines on the scene. Currently I just draw straight lines using GL_LINES. The problem is that the lines...
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    Re: How does OpenGL perform its rendering?

    OK, Thank you.
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    How does OpenGL perform its rendering?

    I need to render a large number of point cloud points, maybe up to 300 million. My concern is blowing out the memory buffer on the graphics card.

    My question is that I'm trying to understand...
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    Re: Video Card Memory Management

    Thank you for the responses.

    The reason the data is 28 bytes per point is that I am using floating point for the data and floating point RGBA for the color.

    I could convert the data to shorts...
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    Video Card Memory Management

    I have a program to display point cloud data and am researching the idea of using VBOs to speed up the display. The catch is that I could be displaying 10-30 million points. Each point requires 28...
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    Re: Zoom to fit screen

    For small angles sin and tangent are almost identical. As the angle increases sin and tanget start to diverge until at 90 degrees (fov = 180) the tangent is infinity and the equation would blow up. ...
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    Re: Zoom to fit screen

    pjcozzi,

    Thank you, that did the trick. I do transformations of sensors mounted on gimbals that rotate in azimuth and elevation, and yaw, roll, pitch of the plane, but I couldn't figure this...
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    Re: Zoom to fit screen

    Here is how I set it up. The xOffset, yOffset and zOffset is just to center the point cloud. Although in my case I need to modify z to fill the screen. Thanks.


    glMatrixMode(GL_PROJECTION);...
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    Re: Zoom to fit screen

    After doing some research I verified that the example in the link above will only work in ortho view. I need to find a way to find the proper range to fill the screen using projections. Thank you.
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    Re: Zoom to fit screen

    Thanks, but that didn't seem to work. I just get a blank screen.

    I noticed that the example uses glOrtho, whereas my program is using gluPerspective. Does that matter?

    Also, the way I...
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    Zoom to fit screen

    I am displaying point cloud data. How do I determine the zoom amount in order to fill the screen? It seems like the data is always either too close or too far away when displayed. Thank you.
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    Lighting of point data

    I am trying to use lighting on point data (using GL_POINTS) but it doesn't seem to have any affect. I am using the same GL commands that I use on facet data and it works with that.

    Is there...
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    Re: Enable & Disable Lighting

    I found the problem. When you define the lighting position using glLightfv, the position is relative to the current model view. When I display the point cloud data I have to apply a large offset to...
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    Re: Enable & Disable Lighting

    I haven't defined vertex colors, and I'm not using texture mapping or fog (or any other special effects). I just use straight lighting. The sample code I included above shows everything I do for...
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    Enable & Disable Lighting

    I am working on a project where I need to be able to enable or disable lighting depending on the type of data (facet models vs. point cloud data).

    The problem I am having is that if I open the...
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