threejs-particle-shader

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This project offers an configurable and easy way to integrate a shader based particle system into a three.js project.
Basically it's a rewrite of my particle shader experiments with the goal to reuse the basic shader code anywhere but keeping everything flexible.

WIP!

Inspired by the "One Million Particles" Chrome Experiment

Usage

1. Load the script from the dist folder

   <script src="https://github.com/pwambach/threejs-particle-shader/raw/master/dist/particles.js"></script>

2. Create a particle system. This function expects your THREE.js WebGL renderer and the rendered scene. Optionally you can customize the particle system by providing an options object.

   var particles = new Particles(renderer, scene, options);

3. To animate the particles you have to update the the system in your render loop.

   particles.update();

Options

• textureSize Integer (Default: 256): Sets the size of the particle shader textures resulting in the number of rendered particles. A size of 256 results in 256*256=65536 particles.

• pointSize Float (Default: 1.0): The size of a single particle (the gl_PointSize value for the display shader)

• gravityFactor Float (Default: 1.0): Gravity Factor for the default particle movement. In case you change the default movement using the velocityFunctionString this variable can be used as a custom input value.

• explodeRate Float (Default: 1.0): The intensity of the initial random velocity and position spread

• targetPosition THREE.Vector3 (Default: (0,0,0)): The position of the gravity center for the default particle movement. You can also use this value for custom movements. Have a look at example 4.

• targetPosition THREE.DataTexture (Default: null): With a targetTexture you can specify a targetPosition for each particle. Have a look at example 3 for how to create a targetTexture.

• velocityFunctionString String (Default: null): The velocityFunctionString allows to change the default behavior of the velocity fragment shader. If a value is specified the original code of the shader will be replaced with the defined string. The value has to be valid GLSL code and should set the variable outVelocity as a vec3. Currently these values are available for calculations:

  inVelocity
  inPosition
  targetPos
  dist        //the distance from the particle to the targetPosition
  direction   //the normalized direction pointing from the particle to the targetPosition

  If you specify a targetTexture, the targetPos will not be the targetPosition from options.targetPosition but the position for this specific particle defined in the targetTexture.

• positionFunctionString String (Default: null): The positionFunctionString works in the same way. The string value will be set in the position fragment shader. pos should be set as a vec3. For now the only input variable is: velocity

• colorFunctionString String (Default: null): The colorFunctionString works in the same way. The string value will be set in the displays fragment shader. color should be set as a vec4. For now the only input variables are: dist, alpha

License

MIT