Polar to Cartesian
/**
* Polar to Cartesian
* by Daniel Shiffman.
*
* Convert a polar coordinate (r,theta) to cartesian (x,y).
* The calculations are x=r*cos(theta) and y=r*sin(theta).
*/
float r;
// Angle and angular velocity, accleration
float theta;
float theta_vel;
float theta_acc;
void setup() {
size(640, 360);
// Initialize all values
r = height * 0.45f;
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/2.0f, height/2.0f);
// 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, 32, 32);
// Apply acceleration and velocity to angle
theta_vel += theta_acc;
theta += theta_vel;
}