Creating a union of lines with specified strokeWeight

General Discussion Other

ryodejane..

Creating a union of lines with specified strokeWeight

in General Discussion • Other • 1 month ago

Hi, I am trying to achieve the "unite" function in Pathfinder of Adobe Illustrator to draw lines of different stroke weight and stroke joint, then get a union of shapes. In illustrator, I would expand the strokes first to outline, and unite them in Pathfinder.

One easy work around is just to draw the lines with a specific color, export as a pdf and use the illustrator to select and unite them.... but how can I achieve this in Processing sketch?

So far, I tried using Geomerative library to union RShapes. The union works well with primitive shapes, such as rectangle and circle, but I get odd shapes when I get RShape from RPath with stroke setting and get a union....

This seems something easy to achieve to novice, but is it something difficult to achieve?

Any advice would be appreciated.

Replies(5)

tfguy44

Re: Creating a union of lines with specified strokeWeight

1 month ago

First of all, there's no point in doing this if the lines are drawn with a solid color.

If they were a solid color, you could just draw the lines each time you needed them, and the overlapping area would just be the solid color.

There's probably a good way of doing this using off-screen PGraphic objects and the mask() function.
You would basically draw the lines as a solid white, and then use that as the mask for a transparent color.

Trying to do it based on points and drawing it with arcs and lines seems like the wrong approach to me.

Example to come. Stay tuned.

tfguy44

Re: Creating a union of lines with specified strokeWeight

1 month ago

Hrm. The alpha channel info got lost somewhere. I'm not happy about this. Someone else fix this.

PGraphics mm, pg;
PImage result;
void setup(){
size(400,400);
background(255,0,0);
noStroke();
fill(0,255,0);
rect(0,0,width/2,height);
/* // The old way to do it.
stroke(0,0,255,128);
strokeWeight(20);
line(20,20,width-20,height-20);
line(width-20,20,20,height-20);
line(20,60,width-20,60);
*/
// Instead...
mm = createGraphics(width,height,P2D);
mm.beginDraw();
mm.background(0);
mm.strokeWeight(20);
mm.stroke(255);
mm.line(20,20,width-20,height-20);
mm.line(width-20,20,20,height-20);
mm.line(20,60,width-20,60);
mm.endDraw();
pg = createGraphics(width,height,P2D);
pg.beginDraw();
pg.background(0,0,255,128);
pg.endDraw();
result = pg.get();
result.mask( mm.get() );
image( result, 0, 0 );
noLoop();
}
void draw(){}

dimkir

Re: Re: Creating a union of lines with specified strokeWeight

1 month ago

Based on tfguy44 code:

Mask applied to image

Now hold the mouse to see just the mask

Just remember to add image kitten.jpg to your data directory

PGraphics mm, pg;
PImage result;
PImage kittens;
void setup(){
size(400,400);
kittens= loadImage("kittens.jpg");
kittens.resize(width, height);
background(255,0,0);
noStroke();
fill(0,255,0);
rect(0,0,width/2,height);
/* // The old way to do it.
stroke(0,0,255,128);
strokeWeight(20);
line(20,20,width-20,height-20);
line(width-20,20,20,height-20);
line(20,60,width-20,60);
*/
// Instead...
mm = createGraphics(width,height);
mm.beginDraw();
mm.background(0);
mm.strokeWeight(40);
mm.stroke(#0000FF);
mm.line(20,20,width-20,height-20);
mm.line(width-20,20,20,height-20);
mm.line(20,60,width-20,60);
mm.endDraw();
pg = createGraphics(width,height);
pg.beginDraw();
//pg.background(110,10,155,128); // purple
pg.image(kittens,0,0);
pg.endDraw();
result = pg.get();
result.mask( mm.get() );
image( result, 0, 0 );
//noLoop();
}
void draw(){
background(0);
if ( mousePressed ){
image(mm, 0,0);
}
else{
image(result, 0,0);
}
}

PhiLho

Re: Creating a union of lines with specified strokeWeight

1 month ago

" This seems something easy to achieve to novice, but is it something difficult to achieve?"
Yes...

(Geomerative does lot of difficult things to look easy. If it fails somewhere, then that's even harder to do!)
Perhaps contact the author of the library. If he has time, perhaps he can see the challenge as something entertaining.

carloalan

Re: Creating a union of lines with specified strokeWeight

1 month ago

hey there...

do you have the code from your RShape approach? I also had a problem when starting to use it, but it only appeard when you have a whole in your shape ...

and it gets worse if you have more than one whole.

is that your problem? or does it come up even when you dont have wholes?
i dont want to start writing and explaining (because its quite complicated) before knowing your real problem!

good luck

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