Why does the subtraction of two shapes still intersect?

73 views

Skip to first unread message

Richard JE Cooke

unread,

May 31, 2022, 4:46:54 PM5/31/22

to Paper.js

Surely shape1.subtract(shape2).intersects(shape2) should always be false?

Why is this happening please?

----

Here's some test code if you want to see:

<!DOCTYPE html>

<head>

<style>

body { padding: 0; margin: 0; background-color: black; }

canvas { background-color: darkgrey; }

</style>

'use strict';

window.onload = setup;

let p = null; // an alias for the paper.js global object.

let canvasWidth, canvasHeight = null;

let em = null; // relative width unit the drawing is based on

function setup()

{

p = paper;

const canvas = document.getElementById('canvasId');

canvasWidth = parseInt(document.getElementById('canvasId').attributes.width.nodeValue);

canvasHeight = parseInt(document.getElementById('canvasId').attributes.height.nodeValue);

em = canvasWidth / 100;

p.setup(canvas);

drawPicture();

}

function drawPicture()

{

const shape1 = p.Path.Circle(new p.Point(200, 200), 2*em);

shape1.fillColor = hsb(50, 0.5, 0.5, 1);

shape1.strokeColor = hsb(0, 0, 0, 1);

const shape2 = p.Path.Circle(new p.Point(230, 200), 2*em);

shape2.fillColor = hsb(100, 0.5, 0.5, 1);

shape2.strokeColor = hsb(0, 0, 0, 1);

console.log(`shape1 intersects shape1 ? ${shape1.intersects(shape1)}`);

console.log(`shape1 intersects shape2 ? ${shape1.intersects(shape2)}`);

console.log(`(shape1 less shape2) intersects shape2 ? ${shape1.subtract(shape2).intersects(shape2)}`);

}

function hsb(hue = 360, saturation = 1, brightness = 0.5, alpha = 1)

{

return new p.Color({hue: hue, saturation: saturation, brightness: brightness, alpha: alpha});

}

</script>

</head>

<body>

</main>

</body>

</html>

Richard JE Cooke

unread,

Jun 3, 2022, 2:36:39 PM6/3/22

to Paper.js

Posted question on stackoverflow for help: https://stackoverflow.com/questions/72493840/why-does-the-subtraction-of-two-svg-shapes-still-intersect

Reply all

Reply to author

Forward

0 new messages