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Jitter / Perf issue

February 19, 2014 | 2:46 am

Hi
I am new to this community and a beginner with Jitter.
I have a very straightforward issue which I am sure someone can help me with.
I need to display in a CPU-effective way a 3D object which is just a cloud of numerous (possibly > 500k) points. I don’t care about building volumes, surfaces, textures.
Just the plain cloud of points.
By display, I mean, obviously, zoom into, rotate, translate. The kind of stuff jit.gl.render can do.
Help !



dtr
February 19, 2014 | 3:11 am

Well you already said it, the stuff jit.gl.render can do. Use jit.gl.mesh and send it a matrix containing the positions of your points.

How many points you’ll be able to visualize at a decent framerate depends on your hardware.

There’s 1 caveat that might or might not affect you. Points have no volume. They get drawn according to the point_size attribute you set on the jit.gl.mesh. This means that a point close by and far away have the same size. If you need them to look larger/smaller depending on how far they are you have to give them a volume. You might wanna use jit.gl.multiple then. Maybe there other tricks for that, not sure.


February 19, 2014 | 6:19 am

it works perfectly ! thx !!


March 29, 2014 | 12:54 pm

Now I have another performance issue. I would like my cloud of 1 million points (X,Y,Z) to be colored according to a very simple formula R=G=f(X^2+Y^2,a), B=255
where the parameter "a" changes at each frame but has a limited number N of values.

Basically the closer a point is to the Z-axis, the bluer ; the further, the whiter. But with the parameter "a", I can introduce a pulse in the colur of the cloud.

Calculating at each frame a matrix of coulors and giving it to my jit.gl.mesh object takes too long.

Any idea of how to make this more efficient ? Use the capabilities of my GPU in this regard too ?

I could precalculate N 3D-images that are Z-cylinders of color going from blue to white, but then what ? How can I "mix" the images to render the cloud of points with the right color ?

Thx for your help


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