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javascriptsvgthree.jscomputational-geometry

Extrude Geometry in three.js

I'm currently loading an STL onject into my three.js scene.

For some reason, it takes a lot of GPU resources to render/animate, slowing the entire scene down so I've been considering alternatives.

As it's quite a simple shape, I thought I could use create the 2D shape and extrude it.

The 3D shape is a square frame (it's a photo frame), no curves or any other clever geometry.

Initially, I thought about creating 4x 3D oblongs, rotating each one by 90 degrees and placing them just right in the scene to make it look like a frame - but that's not ideal.

Here's a 2D shape (it's perfectly square):

And here's a preview of the STL model

So as an alternative to loading the STL model into the scene, how can I create this shape in three.js (with empty space in the centre) and then extrude it to give it some depth?

Solution

  • Basic extrusion example: Shape -> ExtrudeGeometry -> Mesh

    const { renderer, scene, camera } = initThree();


//Create a frame shape..
var frame = new THREE.Shape();
frame.moveTo(-4, -3);
frame.lineTo( 4, -3);
frame.lineTo( 4,  3);
frame.lineTo(-4,  3);

//..with a hole:
var hole = new THREE.Path();
hole.moveTo(-3, -2);
hole.lineTo( 3, -2);
hole.lineTo( 3,  2);
hole.lineTo(-3,  2);
frame.holes.push(hole);

//Extrude the shape into a geometry, and create a mesh from it:
var extrudeSettings = {
    steps: 1,
    depth: 1,
    bevelEnabled: false,
};
var geom = new THREE.ExtrudeGeometry(frame, extrudeSettings);
var mesh = new THREE.Mesh(geom, new THREE.MeshPhongMaterial({ color: 0xffaaaa }));


scene.add(mesh);
renderer.render(scene, camera);
    body {
    margin: 0;
    overflow: hidden;
}
canvas {
    display: block;
}
    <script src="//cdnjs.cloudflare.com/ajax/libs/three.js/102/three.min.js"></script>
<script src="//cdn.rawgit.com/Sphinxxxx/298702f070e34a5df30326cd9943260a/raw/16afc701da1ed8ed267a896907692d8acdce9b7d/init-three.js"></script>