Drawing lines with user defined coordinates

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thor_wium..

Drawing lines with user defined coordinates

in Programming Questions • 5 months ago

Hi guys. So i´ve just started playing around with processing and i am trying to write a program that lets the user click at two random points on the screen and then a line should appear between these two points.

i´ve written the following code, but i wont work and i just cant figure out why :S .. Can anyone explain it to me?

Thanks in advance.

void setup(){
size(400,400);
smooth();
}
void draw(){
int pointOneX;
int pointOneY;
int pointTwoX;
int pointTwoY;
boolean pointStored = false;
if(mousePressed){
if(pointStored == true){ //if coordinates for the starting point of the line has been recorded, the line is drawn and the boolean pointStored is set to false so that the next line can be drawn.
pointTwoX = mouseX;
pointTwoY = mouseY;
line(pointOneX,pointOneY,pointTwoX,pointTwoY);
pointStored = false;
}else{ // coordinates for the starting point of the line is recorded
pointOneX = mouseX;
pointOneY = mouseY;
pointStored = true;
}
}
}

Replies(3)

pauline303

Re: Drawing lines with user defined coordinates

5 months ago

gotoloop solution !

PhiLho

Re: Drawing lines with user defined coordinates

5 months ago

It is good to look at other's solutions, but It is also good to learn from own's mistakes!
Your attempt cannot work, because you declare the variables inside draw(): a variable declared between two braces { } will disappear after the closing brace, and its value with it.
Side note and pet peeve: boolean variables can be used directly in conditions: if (pointStored) { }
In your case, it is better to use the mousePressed() function.
And you can use the variables pmouseX and pmouseY, so you can avoid storing the coordinates, actually.

GoToLoop

Re: Drawing lines with user defined coordinates

5 months ago

And you can use the variables pmouseX and pmouseY,

so you can avoid storing the coordinates, actually.

Excellent idea! Removed all variables from my example. But left out the final constants!

Click below to view it online too:

http://studio.processingtogether.com/sp/pad/export/ro.9c9DCUznTwot6/latest

/** * ClickLine (v2.0) * by GoToLoop (2013/Apr) * * http://forum.processing.org/topic/mouse-click * http://forum.processing.org/topic/drawing-lines-with-user-defined-coordinates * * http://studio.processingtogether.com/sp/pad/export/ro.9c9DCUznTwot6/latest */

final static color BG = #4080A0, FG = #FFFF00;
final static short BOLD = 3, FPS = 30;

void setup() {
  size(600, 400);
  frameRate(FPS);
  noLoop();
  smooth();

  background(BG);
  stroke(FG);
  strokeWeight(BOLD);
}

void draw() {
  println(mouseX + "\t" + mouseY);

  if ( (frameCount & 1) == 0 ) {
    background(BG);
    point(mouseX, mouseY);
    return;
  } 

  line(pmouseX, pmouseY, mouseX, mouseY);
  println();
}

void mouseClicked() {
  redraw();
}

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