Particle System Performance

Processing Project Guidance
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Hello everyone!
I am looking for advice on a project : I am simulating a few thousands of microorganisms (microalgae). I need to simulate the physics for each of them, applying three forces : fluid friction which limits velocity; collision, or rather repulsion based on distance; and a random force to deviate trajectories a bit and make it look like brownian movements.
I took a look at a few basic Particle System examples, I adapted the ParticleSystemPShape example in Topics/Create Shapes, but the frameRate drops with the number of particles I am generating. Even when I am not updating the physics, simply calling shape(shapegroup) on the shape of type GROUP that contains all the child shapes, I get a low framerate…
I also took a look at the PixelFlow library by Thomas Diewald, but all the Particle System examples show plain ellipse shapes (in need textured quads), and besides I tried diving into the source code and reference but it is couldn’t quite figure how and if I could adapt it to suit my needs.

So my question would be : does anyone know of an efficient way to update and display multiple quad shapes?
I have been coding fragment shaders lately, and I guess shaders would probably be a good way to make all this more efficient.
If anyone has tips, example projects, that would be very helpful!

Thank you :slight_smile:

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I’m not sure what you mean by quad shapes. Can you clarify? I’ve worked in 3-d programs with quads and tesselations and such, but it sounds like you want a 2-d simulation and I’m not sure how that might apply.

Have you taken a look at Fisica?

http://www.ricardmarxer.com/fisica/

I’m not sure it will be up to your needs, but I’ve done simulations with up to 2040 objects. It throws an “assertion error” at 2048 objects. It’s been a few years since I tried, but I haven’t been able to find my way around that limit. There have been a few minor updates to Fisica, but the system doesn’t seem to be in active development. Take a look at the examples to see if it might be of use.

More references:
http://www.ricardmarxer.com/fisica/reference/index.html

http://mycours.es/fisica/

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I mean PShape instances of type QUAD, with a PNG texture, 4 vertices. Similar to the Demos/Performance/DynamicParticlesRetained example. Like this :

PShape part = createShape();
part.beginShape(QUAD);
part.noStroke();
part.texture("image.png");
part.normal(0, 0, 1);
part.vertex(-partSize/2, -partSize/2, 0, 0);
part.vertex(+partSize/2, -partSize/2, sprite.width, 0);
part.vertex(+partSize/2, +partSize/2, sprite.width, sprite.height);
part.vertex(-partSize/2, +partSize/2, 0, sprite.height);
part.endShape();

Thank you for suggesting Fisica, unfortunately 2048 particles is not enough for my project…

I ended up doing this the basic way, still doing all the physics computation in the CPU, I got about 8000 at 25fps… So I am still looking for a shader way to optimise all this and get more particles, but for now I get by :slight_smile:

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Hi @wqt,

Have you considered using JCuda for GPU computing ?

An old thread showing a use case within Processing.

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