mirror of
https://github.com/processing/processing4.git
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55 lines
1.5 KiB
Plaintext
55 lines
1.5 KiB
Plaintext
/**
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* Smoke Particle System
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* by Daniel Shiffman.
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*
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* A basic smoke effect using a particle system. Each particle
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* is rendered as an alpha masked image.
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*/
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// @pjs preload must be used to preload media if the program is
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// running with Processing.js
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/* @pjs preload="texture.png"; */
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ParticleSystem ps;
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void setup() {
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size(640,360);
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PImage img = loadImage("texture.png");
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ps = new ParticleSystem(0,new PVector(width/2,height-60),img);
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}
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void draw() {
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background(0);
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// Calculate a "wind" force based on mouse horizontal position
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float dx = map(mouseX,0,width,-0.2,0.2);
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PVector wind = new PVector(dx,0);
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ps.applyForce(wind);
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ps.run();
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for (int i = 0; i < 2; i++) {
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ps.addParticle();
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}
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// Draw an arrow representing the wind force
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drawVector(wind, new PVector(width/2,50,0),500);
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}
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// Renders a vector object 'v' as an arrow and a location 'loc'
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void drawVector(PVector v, PVector loc, float scayl) {
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pushMatrix();
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float arrowsize = 4;
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// Translate to location to render vector
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translate(loc.x,loc.y);
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stroke(255);
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// Call vector heading function to get direction (note that pointing up is a heading of 0) and rotate
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rotate(v.heading());
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// Calculate length of vector & scale it to be bigger or smaller if necessary
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float len = v.mag()*scayl;
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// Draw three lines to make an arrow (draw pointing up since we've rotate to the proper direction)
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line(0,0,len,0);
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line(len,0,len-arrowsize,+arrowsize/2);
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line(len,0,len-arrowsize,-arrowsize/2);
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popMatrix();
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}
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