topical media & game development
#javascript-processing-example-basic-math-sinewave.htm / htm
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<script src="javascript-processing-example-processing.js"></script>
<script src="javascript-processing-example-init.js"></script>
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</head><body><h1><a href="http://ejohn.org/blog/processingjs/">Processing.js</a></h1>
<h2>SineWave</h2>
<p>by Daniel Shiffman.
Render a simple sine wave.</p>
<p><a href="http://processing.org/learning/basics/sinewave.html"><b>Original Processing.org Example:</b> SineWave</a><br>
<script type="application/processing">
int xspacing = 8; // How far apart should each horizontal location be spaced
int w; // Width of entire wave
float theta = 0.0; // Start angle at 0
float amplitude = 75.0; // Height of wave
float period = 500.0; // How many pixels before the wave repeats
float dx; // Value for incrementing X, to be calculated as a function of period and xspacing
float[] yvalues; // Using an array to store height values for the wave (not entirely necessary)
void setup() {
size(200,200);
frameRate(30);
colorMode(RGB,255,255,255,100);
smooth();
w = width+16;
dx = (TWO_PI / period) * xspacing;
yvalues = new float[w/xspacing];
}
void draw() {
background(0);
calcWave();
renderWave();
}
void calcWave() {
// Increment theta (try different values for 'angular velocity' here
theta += 0.02;
// For every x value, calculate a y value with sine function
float x = theta;
for (int i = 0; i < yvalues.length; i++) {
yvalues[i] = sin(x)*amplitude;
x+=dx;
}
}
void renderWave() {
// A simple way to draw the wave with an ellipse at each location
for (int x = 0; x < yvalues.length; x++) {
noStroke();
fill(255,50);
ellipseMode(CENTER);
ellipse(x*xspacing,width/2+yvalues[x],16,16);
}
}
</script><canvas width="200" height="200"></canvas></p>
<div style="overflow: hidden; height: 0px; width: 0px;"></div>
<pre><b>// All Examples Written by <a href="http://reas.com/">Casey Reas</a> and <a href="http://benfry.com/">Ben Fry</a>
// unless otherwise stated.</b>
int xspacing = 8; // How far apart should each horizontal location be spaced
int w; // Width of entire wave
float theta = 0.0; // Start angle at 0
float amplitude = 75.0; // Height of wave
float period = 500.0; // How many pixels before the wave repeats
float dx; // Value for incrementing X, to be calculated as a function of period and xspacing
float[] yvalues; // Using an array to store height values for the wave (not entirely necessary)
void setup() {
size(200,200);
frameRate(30);
colorMode(RGB,255,255,255,100);
smooth();
w = width+16;
dx = (TWO_PI / period) * xspacing;
yvalues = new float[w/xspacing];
}
void draw() {
background(0);
calcWave();
renderWave();
}
void calcWave() {
// Increment theta (try different values for 'angular velocity' here
theta += 0.02;
// For every x value, calculate a y value with sine function
float x = theta;
for (int i = 0; i < yvalues.length; i++) {
yvalues[i] = sin(x)*amplitude;
x+=dx;
}
}
void renderWave() {
// A simple way to draw the wave with an ellipse at each location
for (int x = 0; x < yvalues.length; x++) {
noStroke();
fill(255,50);
ellipseMode(CENTER);
ellipse(x*xspacing,width/2+yvalues[x],16,16);
}
}</pre>
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(C) Æliens
20/2/2008
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