Making a line track the cursor

CantSayIHave

I'm guessing this is a fairly common question, but I need to make a line from, say, (100,100) with a length of 30 track the cursor. I tried converting to polar coordinates and back to cartesian, but I'm running into lots of errors.

Thanks

TfGuy44

PVector p = new PVector(0,0,0);

void setup(){
  size(400,400);
  stroke(255);
}

void draw(){
  background(0);
  p.x = mouseX - width/2;
  p.y = mouseY - height/2;
  translate(width/2,height/2);
  p.normalize();
  line(0,0,30*p.x,30*p.y);
}

_vk

PVector origin, end;
float range = 30;


void setup(){
    size(300,300);
    origin = new PVector (100,100);
    end = new PVector (0,0);
    }


void draw(){
    background(255);
    float a = atan2(mouseY - origin.y, mouseX - origin.x);
    end.x = origin.x + cos(a)*range;
    end.y = origin.y + sin(a)*range;


    line(origin.x, origin.y, end.x, end.y);
    }