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gistfile1.java

/* The follow thru web */

int previousX = 0;
int previousY = 0;
boolean isDrawing = true;

void setup()
{
   size(300, 300);
   background(0);
   strokeWeight(10.0);
}

void draw()
{
   int newX = mouseX;
   int newY = mouseY;
   
   // prevent redrawing on the same line
   if (newX != previousX && newY != previousY)
   {
       stroke(random(255), random(255), random(255)); 
   
       line(previousX, previousY, newX, newY);
   
       previousX = newX;
       previousY = newY;
   }
}