0

I'm new to the area of geometry generation and manipulation and I'm planning on doing this on an intricate and large scale. I know the basic way of doing this is like it's shown in the answer to this question.. 

var geom = new THREE.Geometry(); 
var v1 = new THREE.Vector3(0,0,0);
var v2 = new THREE.Vector3(0,500,0);
var v3 = new THREE.Vector3(0,500,500);

geom.vertices.push(v1);
geom.vertices.push(v2);
geom.vertices.push(v3);

geom.faces.push( new THREE.Face3( 0, 1, 2 ) );
geom.computeFaceNormals();

var object = new THREE.Mesh( geom, new THREE.MeshNormalMaterial() );

object.position.z = -100;//move a bit back - size of 500 is a bit big
object.rotation.y = -Math.PI * .5;//triangle is pointing in depth, rotate it -90 degrees on Y

scene.add(object);

But I do have experience with doing image manipulation working directly with a typed array image buffer on the GPU which is essentially the same thing as manipulating 3D points, since colors are essentially 3D points on a 2D grid (in the case of a buffer, flattened out to a 1D typed array) and I know just how much faster that kind of large scale manipulation is when processed with shaders on the GPU.

So I'm wondering if I can access the geometry in three.js directly as a typed array buffer. If so, I can use gpu.js to manipulate it on the GPU rather than CPU and boost performance exponentially.

Basically I'm asking if there's something like canvas's getImageData method for three.js geometry.

john doe
  • 547
  • 1
  • 6
  • 18
  • 1
    Please take a look at [the documentation](https://threejs.org/docs/), specifically [`BufferGeometry`](https://threejs.org/docs/#api/core/BufferGeometry) as associated objects. `BufferGeometry` is the way of the future, because `WebGL2Renderer` will _only_ support `BufferGeometry`. – TheJim01 May 30 '18 at 18:17

1 Answers1

1

As ThJim01 mentioned in the comment, THREE.BufferGeometry is the way to go, but if you insist on using THREE.Geometry to initialize your list of triangles, you can use the BufferGeometry.fromGeometry function to generate the BufferGeometry from the Geometry you originally made.

var geometry = new THREE.Geometry();
// ... initialize verts and faces ...

// Initialize the BufferGeometry
var buffGeom = new THREE.BufferGeometry();
buffGeom.fromGeometry(geometry);    

// Print the typed array for the position of the vertices
console.log(buffGeom.getAttribute('position').array);

Note that the resultant geometry will not have an index array and just be a list of disjointed triangles (as it was represented as in the first place!)

Hope that helps!

Garrett Johnson
  • 2,413
  • 9
  • 17