computeShaderParticlesExample

Learning Objectives

This example demonstrates how to use a compute shader to set up an animated point cloud with editable parameters. Compute shaders are rather used to do generic computation in contrast to graphics-oriented shaders. In this case the shader computes the movement of particles using a flocking algorithm based on three parameters: attraction, cohesion and repulsion. It additionally includes different forces in order to separate the particles into groups.

You will learn how to..

write a shader that animates particles according to their attraction, cohesion or repulsion
create lively animations using ofNoise()
use ofParameter objects and ofxGui to create editable variables
connect parameters to a shader
set a blend mode
easily navigate in 3D with ofEasyCam

In the code, pay attention to:

the separation of two particle groups by their gl_GlobalInvocationID
the double buffer (ofBufferObject) for faster computation that allows to draw from one buffer while the other one is being updated
the definition of working groups by setting dispatchCompute() from the C++ shader object and layout() from within the shader

Expected Behavior

When launching this app, you should see a cloud of particles floating in the center of a white cube. In the top left corner there is a panel to manipulate the particle cloud. The panel also includes a display of the current framerate.

Instructions for use:

Use the mouse to adjust the interactive camera
- Left click drag = orbit the target
- Right click drag = dolly in and out
- Double click = reset camera position
Change the parameters in the panel to manipulate the particle cloud, for example..
- check "dir as color" to show each particle in a color according to the direction it is heading
- change attr1_force to adjust the force applied to all particles with an odd index
- change attr2_force to adjust the force applied to all particles with an even index

Other classes used in this file

This Example uses the following classes: