Processing 1.0 - Processing Discourse - making line bounce back

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Index › Programming Questions & Help › Syntax Questions › making line bounce back

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making line bounce back (Read 662 times)

chrisgruggen

making line bounce back
Sep 29^th, 2009, 12:27pm

hey there, im kinda new to processing, so i was hoping i could get some help with this. i have my code here:

int x;
int y;

void setup() {
size (400, 400);
x = 100;
background(0);

}

void draw() {
// background (0);

stroke (mouseY, mouseX, random(0, 255), 50);
strokeWeight(1);
line (x, x, mouseX, pmouseY);
x = x - 1;

}

my wish to have the line bouce off the walls so it is not continuously moving off stage. any ideas?

thanks so much for you help, chris

Cedric

Re: making line bounce back
Reply #1 - Sep 29^th, 2009, 1:25pm

its just moving off the stage because you substract 1 from x with every frame. So one point of your line is moving further away in the upper left corner. the other point is mapped to your mouseX and previous mouseY coordinate. doesnt make much sense with the pmouse but ok, still works though.

So what do you mean by bounce off the wall? could you explain a bit better how your line should behave?

twitter.com/CedricKiefer

PhiLho

Re: making line bounce back
Reply #2 - Sep 29^th, 2009, 2:10pm

Thanks for having deleted the post from the wrong place (Exhibition). Removed my own answer as well...

I wrote: "Check the reference of if and width/height."
The traditional idea is to have a 'dir' variable with value 1 or -1. Instead of doing x = x - 1 (which can be written x -= 1; or even x--;, you do x += dir;. When x reaches 0 or width (tested with 'if'), you change the sign of dir (dir = -dir;).

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