getting points inside a shape

smvalenga

getting points inside a shape

in Contributed Library Questions • 1 year ago

Hey all,

i am starting with geomerative library, so i still have troubles with the basic. hope somebody could give me a suggestion.

I have a shape and an array of points.

I need to check if the points are inside the shape with the boolean contains, and storage the ones that returns true into an array. The problem is that i can not simply add them into an array list, because for my project i need always the same amount of elements in my storage.

Probably i will have to use somehow the getPoints() command but i simply can not figure it out.....

Would somebody please have a suggestion?

Thanks a lot!!

I made this basic sketch just to test on...

import geomerative.*;
RShape shp;
RPoint [] pts= new RPoint [50];
void setup() {
size(1000, 1000);
RG.init( this );
}
void draw () {
background (255);
stroke(0);
strokeWeight(2);
shp = new RShape();
shp.addMoveTo(width/2-200,height/2-100);
shp.addLineTo(width/2+200,height/2-100);
shp.addLineTo(width/2+200,height/2+100);
shp.addLineTo(width/2-200,height/2+100);
shp.addClose();
shp.draw();
float a= shp.getArea();
//println(a);
strokeWeight(1);
for (int i=0; i<pts.length; i++) {
for (int j=0; j<pts.length;j=j+20) {
pts[i]= new RPoint (j*i, j*i);
ellipse (pts[i].x,pts[i].y,5,5);
}
}
// RPoint [] valid pts = shp.contains();
}

Replies(3)

PhiLho

Re: getting points inside a shape

1 year ago

Geomerative is a contributed library => moved.

" i can not simply add them into an array list, because for my project i need always the same amount of elements in my storage."
Perhaps you can change your project?
Anyway, it is easy to convert an array list to an array, so perhaps you can still use this approach.

Chrisir

Re: getting points inside a shape

1 year ago

1.
when the shape has a fill color you know and the background has another color you could check the color (with get) and thus tell whether it's within or not.
(when you don't have the color or it's changing, you can go via a color buffer similar to
http://wiki.processing.org/w/Picking_with_a_color_buffer - just use the points coor instead of the Mouse Position)

2.
Addtionally you can first check whether it's in an rectangle that sorrounds the shape (maybe faster).

dimiro

Re: getting points inside a shape

1 year ago

i cannot test it right now but i assume if you declare a variable lets say newSize=0 and inside the loop do:

if(shp.contains(pts[i])){
newSize++;
}//IF

newSize should give you the number of ellipses that are inside the square (count them and print newSize to check if it holds), declare another RPoint array

RPoint [] temp=new RPoint[newSize]

and then with another loop you can rewrite the coordinates
( i can try this maybe tomorrow)