Why OPENGL canvas drops framerate?

Programming Questions

jcakec

Why OPENGL canvas drops framerate?

in Programming Questions • 3 years ago

hello,

I have been testing a lot around, and hope someone can help me out.

if I run the following code:

import processing.opengl.PGraphicsOpenGL;
void setup()
{
size(900, 450, OPENGL);
smooth();
background(0);
frameRate(2000);
}
void draw()
{
loadPixels();
println(frameRate);
}

framerate drops from 2000 to 12. no other code is ran.
If I use P2D or P3D framerate is 2000.
I've tested this on 3 different computers with NVidia, GForce GFX (1GB GFX dedicated ram), Linux and Windows.

the culprit framerate kill is the loadPixels();. is there a way to solve this framerate drawback?

please let me know if you have the same problems or if you know how to sole this. thanks in advanced

Replies(5)

kevin.bjo..

Re: Why OPENGL canvas drops framerate?

3 years ago

if you actually draw anything, does that 2000 frameRate hold?

kb, http://www.riftgame.com/

jcakec

Re: Re: Why OPENGL canvas drops framerate?

3 years ago

Kevin,

drawing basic graphics gives up to 1000 fps. with my animations and all processing, the frames goes down to 300~500 fps.

This is an Ubuntu 10.04 Core 2 Duo 2.0 Ghz 4GB RAM and GForce 9500 1GB gfx. dedicated for processing only. the problem is that it is only giving 256 MB RAM on excecution, even though I changed it to 1 GB on preferences. I will try to figure out if there is a possibility to give higher priority to the threads so they can consume more CPU cicles and memory. that would keep the framerate high.

PhiLho

Re: Why OPENGL canvas drops framerate?

3 years ago

We have discussed that in another thread: to my knowledge, doing loadPixels on OpenGL need to access the GPU memory, transfer it and process it. It is time consuming. I think you might have poor performances in Java2D mode too (converting from BufferedArray to Processing array). P2D and P3D natively use an array of pixels, so loadPixels in these mode is a null operation.
OpenGL isn't a good fit for pixel operations (to my knowledge), at least with the Processing functions (it might have native pixel manipulation primitives, I am not an OpenGL specialist).

pixelnerve

Re: Why OPENGL canvas drops framerate?

3 years ago

What phi.lho said.
opengl isn't that good for pixel operations. in that case you might want to move to shaders, or probably take a look at PBO (PixelBufferObjects). OpenCL also comes to mind.

Actually it depends but, if you're target is to handle pixel arrays, better go with p2d or p3d imho

jcakec

Re: Re: Why OPENGL canvas drops framerate?

3 years ago

thanks phi.lho and pixelnerve,

I have been testing out and reading around. I am trying the GLGraphics library (GLGraphicsOffScreen) and it goes back to 50 FPS, which is still effective for realtime animation. I will try to move the ripple effect to a glsl effect and hope it works out.

My problem is that I am animating fish and rays usig the technique in the koi pond, and that uses OpenGL. every other thing can be done using P2D. I will test and hope it works out.

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