topical media & game development
graphic-processing-site-examples-Basics-Math-PolarToCartesian-PolarToCartesian.pde / pde
PolarToCartesian
by Daniel Shiffman.
Convert a polar coordinate (r,theta) to cartesian (x,y):
x = r * cos(theta)
y = r * sin(theta)
float r;
// Angle and angular velocity, accleration
float theta;
float theta_vel;
float theta_acc;
void setup() {
size(200,200);
frameRate(30);
smooth();
// Initialize all values
r = 50.0f;
theta = 0.0f;
theta_vel = 0.0f;
theta_acc = 0.0001f;
}
void draw() {
background(0);
// Translate the origin point to the center of the screen
translate(width/2,height/2);
// Convert polar to cartesian
float x = r * cos(theta);
float y = r * sin(theta);
// Draw the ellipse at the cartesian coordinate
ellipseMode(CENTER);
noStroke();
fill(200);
ellipse(x,y,16,16);
// Apply acceleration and velocity to angle (r remains static in this example)
theta_vel += theta_acc;
theta += theta_vel;
}
(C) Æliens
20/2/2008
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