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Index › Programming Questions & Help › Programs › uncovering an image
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uncovering an image (Read 579 times)
Maxoe
uncovering an image
Feb 7th, 2009, 5:25pm  
Not necessarily looking for exact code, although not opposed to it, but how would you go about making a program that loads a picture to the background and then covers said image with a strait fill color of say gray, and when the mouse hovers over the picture it uncovers the part of the picture under it with a square like eraser type tool.  As you move the mouse over the picture, the parts you have uncovered stay uncovered.  Sort of like in paint when your erasing something, only under all he gray is a picture that does not get erased with it.
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NoahBuddy
Re: uncovering an image
Reply #1 - Feb 8th, 2009, 6:38am  
You can use an alpha mask
http://processing.org/reference/PImage_mask_.html

with PGraphics
http://processing.org/reference/PGraphics.html

Draw (in black and white) your mask onto a PGraphics object and use that as a mask for your image.

I do have a working example if you have trouble.
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Maxoe
Re: uncovering an image
Reply #2 - Feb 9th, 2009, 11:29pm  
Having a little trouble getting it to work, if its not a big deal could i see your working example?

Thanks in advance
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NoahBuddy
Re: uncovering an image
Reply #3 - Feb 10th, 2009, 7:17am  
Not a problem.

Code:

PImage img;
PGraphics maskg;

void setup() {
  size(200,200);
  img = loadImage("test.jpg");
  maskg = createGraphics(img.width, img.height, P2D);
}

void mouseMoved() {
  maskg.beginDraw();//do not call background here or it will only show one box
  maskg.noStroke();
  maskg.fill(255);
  maskg.rect(mouseX-10,mouseY-10,20,20);
  maskg.endDraw();
}

void draw() {
  background(0);
  img.mask(maskg);
  image(img, 0, 0);
}
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PhiLho 
Re: uncovering an image
Reply #4 - Feb 10th, 2009, 1:19pm  
See also causing pixels to fall (from same author).
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WWW  
Maxoe
Re: uncovering an image
Reply #5 - Feb 10th, 2009, 3:24pm  
Ok thanks a ton guys.
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