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cool mistake (Read 2150 times)

Rick

cool mistake
May 21^st, 2009, 9:17am

I stumbled on the following when I accidentally put a straight integer instead of a color. I love how Processing works like that. Anyway, thought it was interesting enough to post. Quote:

int rad = 200; //radius

void setup() {
  size(400,400,P3D);
  noFill();
  background(0);
  loadPixels();
}
void draw() {
  for(int a=0; a<pixels.length; a++) {
    float d = dist(mouseX, mouseY, a%400, (a-a%400)/400);
    //move your mouse
    //a%400 x coord from index, (a-a%400)/400 y coord from index
    if(d <= rad) {
      if(brightness(pixels[a])<255)
      pixels[a] += lerpColor(pixels[a], color(255), 1-d/rad)<<17;
      //pixels[a] = lerpColor(pixels[a], color(255), 1-d/rad);
      //use commented line above instead for something more sane
    }
  }
  updatePixels();
}
void mouseClicked() {
  //click to clear
  for(int a=0; a<pixels.length; a++) {
    pixels[a] = 0;
  }
  updatePixels();
}

http://r6753.com/ _{I need a job.}

Cedric

Re: cool mistake
Reply #1 - May 21^st, 2009, 11:31am

I like playing arround with it. thats what i came up with

float rad = 100; //radius

void setup() {
size(400,400,P3D);
noFill();
background(0);
loadPixels();
}
void draw() {
rad = 10+(frameCount%200);
float x= width/2+sin(frameCount/3)*100;
float y= height/2+cos(frameCount/3)*100;

fill(0,20);
rect(0,0,400,400);
for(int a=0; a<pixels.length; a+=1) {
float d = dist(x, y, a%400, (a-a%400)/400);

if(d <= rad) {
if(brightness(pixels[a])<255)
pixels[a] += lerpColor(pixels[a], color(255), 1-d/rad)<< 16;
pixels[a] = lerpColor(pixels[a], color(255), 1-d/rad*1.2);
//use commented line above instead for something more sane
}
}
updatePixels();
}
void mouseClicked() {
//click to clear
for(int a=0; a<pixels.length; a++) {
pixels[a] = 0;
}
updatePixels();
}

twitter.com/CedricKiefer

Blaine YaBB Newbies Offline Posts: 17	Re: cool mistake Reply #2 - May 21^st, 2009, 11:05pm That's seizuretastic.

Rick Junior Member Offline Posts: 78	Re: cool mistake Reply #3 - May 22^nd, 2009, 9:03am Thats an interesting result Cedric. Not what I expected when glancing at your modifications. Perhaps I should have included an epilepsy warning.
	http://r6753.com/ _{I need a job.}

blindfish

Re: cool mistake
Reply #4 - May 22^nd, 2009, 10:18am

Here's a slight variation on the original:

Code:

int rad = 75; //radius
int oldX = 0;
int oldY = 0;
boolean drawOn = false;

void setup() {
  size(400,400,P3D);
  noFill();
  background(0);
  loadPixels();
}
void draw() {
  // fade out the background:
  // (Not sure why background(0,2) doesn't work... it doesn't respect the alpha)
  fill(0,2);
  rect(0,0,width,height);
  
  // Crude way to determine the speed of mouse movement
  float dx = mouseX - oldX;
  float dy = mouseY - oldY;
  float dist = sqrt(dx*dx + dy*dy);
  // As speed increases so does the dist between the old mouse position and the new
  // Only allow drawing when above a certain 'speed':
  if (dist > 10) {
      drawOn = true;
  }
  else {
    drawOn = false;  
  }
  oldX = mouseX;
  oldY = mouseY;
}

// Only draw when the mouse is moving
void mouseMoved() {
  // tests whether the mouse is moving fast enough  
  if (drawOn) {
  for(int a=0; a<pixels.length; a++) {
    float d = dist(mouseX, mouseY, a%400, (a-a%400)/400);
    //move your mouse
    //a%400 x coord from index, (a-a%400)/400 y coord from index
    if(d <= rad) {
      if(brightness(pixels[a])<255)
      pixels[a] += lerpColor(pixels[a], color(255), 1-d/rad)<<17;
      //pixels[a] = lerpColor(pixels[a], color(255), 1-d/rad);
      //use commented line above instead for something more sane
    }
  }
  updatePixels();
  }

}

void mouseClicked() {
 //click to clear
 for(int a=0; a<pixels.length; a++) {
   pixels[a] = 0;
 }
 updatePixels();
}

Where is the what if the what is in why?

Rick

Re: cool mistake
Reply #5 - May 22^nd, 2009, 11:31am

I kind of like the functionality of drawing only when the mouse velocity is over a certain threshold. Here is a simpler way to achieve that:

Code:


  if (mouseX - pmouseX > 3 || mouseY - pmouseY > 3) {
      drawOn = true;
  }
  else {
    drawOn = false;  
  }

This uses pmouse which automatically stores the previous mouse coordinates. I just check if the mouse has moved more than a certain amount in one direction or (or is the ||) the other by differencing the current and former positions.

I think a background fade doesn't work here because we are manipulating the pixels array. The fading you have added produces some interesting effects almost like refraction. Nice.

http://r6753.com/ _{I need a job.}

ben_hem Senior Member Offline Posts: 399 CA, US	Re: cool mistake Reply #6 - May 28^th, 2009, 10:02pm Hey, that is cool. Tweaked it into a simple "drawing toy" -- http://benhem.com/games/rickdraw/ it has some extra "effect" brushes to play with the way the ripples interfere. (absolute value of the hex, inverse ripples..) --Ben

Rick

Re: cool mistake
Reply #7 - May 31^st, 2009, 10:56am

I really like how you set up to for loops so it processes only relevant pixels and not the whole array Ben. I was thinking about doing that. All the interaction you added really makes it more interesting too.

I wondered why your strokes seem to fade in. Also does anyone understand why the banding and interference patterns are produced in the first place?

Edited:

I think theres a feedback loop in there but I never figured out exactly what was happening.

http://r6753.com/ _{I need a job.}

Rapatsk1 Junior Member Offline Posts: 99 www.tiemenrapati.com	Re: cool mistake Reply #8 - May 31^st, 2009, 2:16pm The patterns you get when simply pressing and releasing the mouse button on the same spot intrigue me... different timing yields different patterns. Very nice. edit: and what about the white pixels that emerge after awhile? Also interesting...

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