I have a code which basically draws parallel coordinates using opengl fixed func pipeline. The coordinate has 7 axes and draws 64k lines. SO the output is cluttered, but when I run the code on my laptop which has intel i5 proc, 8gb ddr3 ram it runs fine. One of my friend ran the same code in two different systems both having intel i7 and 8gb ddr3 ram along with a nvidia gpu. In those systems the code runs with shuttering and sometimes the mouse pointer becomes unresponsive. If you guys can give some idea why this is happening, it would be of great help. Initially I thought it would run even faster in those systems as they have a dedicated gpu. My own laptop has ubuntu 12.04 and both the other systems have ubuntu 10.x.
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2 Answers
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Fixed function pipeline is implemented using gpu programmable features in modern opengl drivers. This means most of the work is done by the GPU. Fixed function opengl shouldn't be any slower than using glsl for doing the same things, but just really inflexible.
What do you mean by coordinates having axes and 7 axes? Do you have screen shots of your application?
Mouse stuttering sounds like you are seriously taxing your display driver. This sounds like you are making too many opengl calls. Are you using immediate mode (glBegin glVertex ...)? Some OpenGL drivers might not have the best implementation of immediate mode. You should use vertex buffer objects for your data.
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Maybe I've misunderstood you, but here I go.
There are API calls such as glBegin, glEnd which give commands to the GPU, so they are using GPU horsepower, though there are also calls to arrays, other function which have no relation to API - they use CPU. Now it's a good practice to preload your models outside the onDraw loop of the OpenGL by saving the data in buffers (glGenBuffers etc) and then use these buffers(VBO/IBO) in your onDraw loop.
If managed correctly it can decrease the load on your GPU/CPU. Hope this helps.
Oleg
glGetString(GL_VENDOR)to see who's really doing the rendering. - radical7