Hi, I'm only new to processing and have written a simple automated car(rectangle) which steers around the screen.  I'm not redrawing the background atm because I'm playing with the idea of drawing the path it travels.  It's works, but my problem is that I want it to draw faster but move the same amount each frame.  I have tried wrapping a for loop around the function calls in the draw() structure, but it doesn't work as expected.  Does anyone know hwo to make the car(rectangle) draw faster lines all over the place but still move at the same increment / space each frame?

Here's the code:

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float xVelo, yVelo, x, y, angle, speed, rotation, t;

int screenWidth = 500;
int screenHeight = 500;
int i = 0;

Car car = new Car(screenWidth/2,screenHeight/2,4,2);

void setup() {
 //frame.setUndecorated(true);
 size(screenWidth,screenHeight);
 noStroke();
 background(0);
 framerate(1000);
}

void draw() {
   //background(0);
   car.Move();
   car.Render();
   smooth();
}

class Car {
 float x,y,a,b,speed,steerRate;

 //Main constructor, setup basic parameters
 Car(float ix, float iy, int ia, int ib) {
   x = ix;
   y = iy;
   a = ia;
   b = ib;
   
   speed = 1;
   steerRate = 0.05;
 }
 
 //Method called to move a car
 void Move() {
   float xpos = x;
   float ypos = y;
   
   float rand = random(50);
   if (rand > 48) {
     steerRate = steerRate * -1;
   }    
   
   //Calculate rotation and speed
   t += steerRate;
   angle = cos(t);
   
   //Simple screen edge limitations
   if (x > screenWidth) {
     x = screenWidth;
     speed = speed * -1;
   } else if (x<0) {
     x = 0;
     speed = speed * -1;
   }
   
   if (y > screenHeight) {
     y = screenHeight;
     speed = speed * -1;
   } else if (y<0) {
     y = 0;
     speed = speed * -1;
   }
   
   //Calculate movement
   xVelo = cos(angle) * speed;
   yVelo = sin(angle) * speed;
 
   //Apply movement calculations
   x += xVelo;
   y += yVelo;
 }
 
 //Method called to render a car
 void Render() {
   translate(x,y);
   rotate(angle);
   rectMode(CENTER);
   rect(0,0,a,b);
 }
}

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Here's a suggestion. Instead of essentially implementing a point plot, I'd record 2 point calcs at a time in an array and then use a line call-something like:
line(x[i-1], y[i-1], x[i], y[i])

I'd keep the framerate between 30-60 (preferably nearer 30) and increase the speed variable. The point separation you'll get will be patched by the line segments. Obviously if the separation becomes too great, you'll get some stepping, but you could always then try the curve() call.

My sense looking at your code is that you may be new to Processing, but you're not new to coding, so I suspect you can implement this. Obviously, your current implementation, utilizing iterated translations, will need to be changed, but that shouldn't present a problem.
Does this make sense?

ira

selter's piece is nice. If you can't get the implementation to work, let me know and I'll give it a try.

ira