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cut a hole (Read 276 times)
handyaner
cut a hole
Nov 4th, 2008, 12:24am  
hello

i have got a ellipse and a image. via mouseclick i wan to cut a round hole in he image.
but i don´t know to put into practice

PGraphics pg;  
PImage img;
void setup() {  
 size(300,300);  
 pg = createGraphics(300, 300, JAVA2D);  
 img = loadImage("s.jpg");
}  

void draw(){  
 pg.background(0);
 pg.beginDraw();  
 pg.fill(120,0,0);  
 pg.ellipse(mouseX, mouseY, 50,50);  
 pg.modified = true;  
 pg.endDraw();
image(img, 300, 300);
 image(pg,0,0);
if (mousePressed == true) {
   //cut a hole?
}

}  
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WebDext
Re: cut a hole
Reply #1 - Nov 4th, 2008, 12:44am  
The trick is to draw the image only in the places that are not over the "hole"

Copy is your man:
http://processing.org/reference/copy_.html

Basically just draw the image normally when the mouse isn't pressed, but don't draw the entire image when it is, and you can specify the source rects from the image to copy from.

Well, at least that's one way to do it.

Another would be using a mask or something if you need it to be a non-rectangular hole.
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WWW JacksEvilClone  
handyaner
Re: cut a hole
Reply #2 - Nov 4th, 2008, 12:51am  
but with copy() i can just copy a rectangle and not a ellipse
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WebDext
Re: cut a hole
Reply #3 - Nov 4th, 2008, 1:40am  
Well, then you can go the mask route...

Just create a mask image that's the same size as your image, and set the pixels you want to be visible to 255, and the pixels you want to be transparent to 0. You can use that same PGraphics to render the ellipse to the mask image.

http://processing.org/reference/PImage_mask_.html
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WWW JacksEvilClone  
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