I'm using Three.js to render point cloud data retrieved from a server.
For each data set, I loop over the data points and create a Three.js Vector3 object with x, y & z values corresponding to each data point. I push each of these vertices onto a list which I then pass into the vertices prop of my geometry component within my points component.
render() {
this.pointCloudVertices = [];
if (this.props.points) {
const points = this.props.points
for (let i = 0; i < points.x.length; i++) {
const vertex = new THREE.Vector3();
vertex.x = points.x[i]
vertex.y = points.y[i]
vertex.z = points.z[i]
this.pointCloudVertices.push(vertex);
}
}
return (<points>
<geometry vertices={this.pointCloudVertices}/>
<pointsMaterial
color={ (Math.floor(Math.random()*16777215)) }
size={ 0.2 }
/>
</points>);
}
https://github.com/caseysiebel/pc-client/blob/master/src/components/PointCloud.js
I'd like the user to be able to use their mouse to add points to another point cloud (points component) by clicking inside the canvas.
I found a lot of resources pointing to the Three.js' Raycaster, but this tool seems to be more for selecting out objects already in the canvas. In my case I'd like the user to be able to click on and area in the canvas not occupied by an object, have the client work out the x, y & z coordinates of that click and then add a vertex, with those x/y/z values, to a points component (likely empty until the user adds points via this modality).
I'm a little confused as to how I will convert 2D mouse events into a 3D vertex value. If anyone knows any good resources on this subject I'd love to check them out.
With THREE.Raycaster(), I see several solutions:
1. Use the .at() method of the .ray property. Like this:
raycaster.ray.at(100 + Math.random() * 150, rndPoint);
Here you can set the constraints for the distance from the origin of the ray, and it will look like this from your original camera:
and how it will look like from aside:
jsfiddle example. You can switch the lines off there.
2. Use the .intersectObjects() method. Where intersecting objects are planes of constraints. For example, we have planes in the form of a cube. When we cast a ray through them, we always intersect two planes, and the array of intersectec objects will be sorted by distance from the origin of the ray. Thus the first element in this array will be the closest plane. So, when we know it, we can take their points of intersection and sub point1 from point2, getting a new vector (its length and direction). And then we'll just set a point at a random place along the vector from point1 to point2:
intersected = raycaster.intersectObjects(planes.children);
if (intersected.length > 0){
var point1 = intersected[0].point;
var point2 = intersected[1].point;
var diff = point2.clone().sub(point1);
var diffLength = diff.length();
rndPoint = point1.clone().addScaledVector(diff.normalize(), Math.random() * diffLength);
. . .
}
It will look like this from the front camera:
and from aside:
jsfiddle example. Lines are switchable here too.
Or you can use THREE.Raycaster() with THREE.OrthographicCamera(). Which is simplier )
Related
in my project I have a player walk around a globe. The globe is not just a sphere, it has mountains and valleys, so I need the players z position to change. For this I'm raycasting a single ray from player's position against a single object (the globe) and I get the point they intersect and change players position accordingly. I'm only raycasting when the player moves, not on every frame.
For a complex object it takes forever. It takes ~200ms for an object with ~1m polys (faces) (1024x512 segments sphere). Does raycasting cast against every single face ?
Is there a traditional fast way to achieve this in THREE, like some acceleration structure (octree? bvh? -- tbh from my google searches I haven't seem to find such a thing included in THREE) or some other thinking-out-of-the-box (no ray casting) method?
var dir = g_Game.earthPosition.clone();
var startPoint = g_Game.cubePlayer.position.clone();
var directionVector = dir.sub(startPoint.multiplyScalar(10));
g_Game.raycaster.set(startPoint, directionVector.clone().normalize());
var t1 = new Date().getTime();
var rayIntersects = g_Game.raycaster.intersectObject(g_Game.earth, true);
if (rayIntersects[0]) {
var dist = rayIntersects[0].point.distanceTo(g_Game.earthPosition);
dist = Math.round(dist * 100 + Number.EPSILON) / 100;
g_Player.DistanceFromCenter = dist + 5;
}
var t2 = new Date().getTime();
console.log(t2-t1);
Thank you in advance
Do not use three.js Raycaster.
Consider Ray.js that offers function intersectTriangle(a, b, c, backfaceCulling, target)
Suggested optimizations:
If player starts from some known positions ⇒ you must know his initial height, − no need to raycast (or just do one time full mesh slow intersection)
if player moves with small steps ⇒ next raycast will most likely intersect the same face as before.
Optimization #1 − remember previous face, and raycast it first.
if player does not jump ⇒ next raycast will most likely intersect the adjacent face to the face where player was before.
Optimization #2 − build up a cache, so that given a face idx you could retrieve adjacent faces in O(1) time.
This cache may be loaded from the file, if your planet is not generated in real time.
So with my approach on each move you do O(1) read operation from cache and raycast 1-6 faces.
Win!
For a complex object it takes forever. It takes ~200ms for an object with ~1m polys (faces) (1024x512 segments sphere). Does raycasting cast against every single face ?
Out of the box THREE.js does check every triangle when performing a raycast against a mesh and there are no acceleration structures built into THREE.
I've worked with others on the three-mesh-bvh package (github, npm) to help address this problem, though, which may help you get up to the speeds your looking for. Here's how you might use it:
import * as THREE from 'three';
import { MeshBVH, acceleratedRaycast } from 'three-mesh-bvh';
THREE.Mesh.prototype.raycast = acceleratedRaycast;
// ... initialize the scene...
globeMesh.geometry.boundsTree = new MeshBVH(globeMesh.geometry);
// ... initialize raycaster...
// Optional. Improves the performance of the raycast
// if you only need the first collision
raycaster.firstHitOnly = true;
const intersects = raycaster.intersectObject(globeMesh, true);
// do something with the intersections
There are some caveats mentioned in the README so keep those in mind (the mesh index is modified, only nonanimated BufferGeometry is supported, etc). And there's still some memory optimization that could be done but there are some tweakable options to help tune that.
I'll be interested to hear how this works for you! Feel free to leave feedback in the issues on how to improve the package, as well. Hope that helps!
I think you should pre-render the height map of your globe into a texture, assuming your terrain is not dynamic. Read all of it into a typed array, and then whenever your player moves, you only need to back-project her coordinates into that texture, query it, offset and multiply and you should get what you need in O(1) time.
It's up to you how you generate that height map. Actually if you have a bumpy globe, then you should probably start with height map in the first place, and use that in your vertex shader to render the globe (with the input sphere being perfectly smooth). Then you can use the same height map to query the player's Z.
Edit: Danger! This may cause someone's death one day. The edge case I see here is the nearest collision will be not be seen because searchRange will not contain the nearest triangle but will contain the second nearest one returning it as the closest one. I.e. a robotic arm may stop nearby the torso instead of stopping at the arm right in front of it.
anyway
Here's a hack when raycasting not too far from the previous result i.e. during consecutive mousemove events. This will not work for completely random rays
Mesh raycast supports drawRange to limit how many triangles will be searched. Also each raycast result comes with faceIndex telling which triangle was hit. If you're continuously looking for raycasts i.e. with mousemove or there's a laser linearly scanning a mesh you can first search the area nearby* the previous hit.
triangles' distance in the data may look like they're neighbours but it's not guaranteed they are sorted in any way. Still it's very possible that the close ones in the data are close in space.
let lastFaceIndex = null
const searchRange = 2000 * 3
function raycast(mesh, raycaster) {
// limited search
if (lastFaceIndex !== null) {
const drawRange = mesh.geometry.drawRange
drawRange.start = Math.max(0, lastFaceIndex * 3 - searchRange)
drawRange.count = searchRange * 2
const intersects = raycaster.intersectObjects([mesh]);
drawRange.start = 0
drawRange.count = Infinity
if (intersects.length) {
lastFaceIndex = intersects[0].faceIndex
return intersects[0]
}
}
// regular search
const intersects = raycaster.intersectObjects([mesh]);
if (!intersects.length) {
lastFaceIndex = null
return null
}
lastFaceIndex = intersects[0].faceIndex
return intersects[0]
}
I'm trying to use three.js plane to get the distance from a point to a plane.
I have three points a,b,c, that I calculate the normal like so:
const v = a.clone().sub(c);
const u = b.clone().sub(c);
const normal = u.cross(v);
Then
const plane = new THREE.Plane(normal, (?))
What are you supposed to give in the second argument?
From the docs:
the negative distance from the origin to the plane along the normal vector. Default is 0.
What does that mean?
If I place there the distance of one of the points a,b,c to (0,0,0) (positive and negative distance), like const dist = a.distanceTo(new THREE.Vector3(0,0,0)), then if I do:
plane.distanceToPoint(a);
I'm getting a huge number and not zero, the same happens if I leave that argument empty.
So how can I place that plane at its correct place so that the distance to points on that plane will be zero as it should?
As you have three coplanar points, you can use .setFromCoplanarPoints(a, b, c) method of THREE.Plane().
An example of using it is in this SO answer.
So I'm very new to THREE JS and I've been trying to figure this out for a few hours now, but how do I determine whether or not a mesh is facing a selected point? Essentially what I have is an RTS style game, where you can select a character and select where he moves to. Currently you can select the character and you can select and where you want it to move to on the map and it will start walking, however I can't figure out how to determine if it is facing the right direction. I don't want to use lookAt because I want the mesh to turn while it walks forward, and not do anything instantaneously.
Ideas?
a simple solution is to select arbitrary look vector
var lookVector = new THREE.Vector3(0,0,1);
and when you need to do some check transform a copy of this vector with mesh matrix (make sure matrix is updated and count in the geometry transformations if you did any)
var direction = lookVector.clone().applyMatrix4(mesh.matrix);
var origin = mesh.boundingSphere.center;
var lookVectorAtThisTime = direction.sub(origin);
then calculate the angle to your point of interest
var vectorToPOI = POI.sub(origin);
var angle = lookVectorAtThisTime.angleTo(vectorToPOI);
if(angle < minAngle)
{
//looking at the point
}
you can also calculate your look vector directly from geometry or some other way origin vector can be something else than the center of the object, but this should get you on the right path..
I have a scene with lots of objects using ExtrudeGeometry. Each of these need to update each frame, where the shape that is being extruded is changing, along with the amount of extrusion. The shapes are being generated using d3's voronoi algorithm.
See example.
Right now I am achieving this by removing every object from the scene and redrawing them each frame. This is very costly and causing performance issues. Is there a way to edit each mesh/geometry instead of removing from the scene? Would this help with performance? Or is there a more efficient way of redrawing the scene?
I'd need to edit both the shape of the extrusion and the amount of extrusion.
Thanks for taking a look!
If you're not changing the number of faces, you can use morph targets http://threejs.org/examples/webgl_morphtargets.html
You should
Create your geometry
Clone the geometry and make your modifications to it, such as the maximum length of your geometry pillar
Set both geometries as morph targets to your base geometry, for example
baseGeo.morphTargets.push(
{ name: "targetName", vertices: [ modifiedVertexArray ] }
);
After that, you can animate the mesh this using mesh.updateMorphTargets()
See http://threejs.org/examples/webgl_morphtargets.html
So I managed to come up with a way of not having to redraw the scene every time and it massively improved performance.
http://jsfiddle.net/x00xsdrt/4/
This is how I did it:
Created a "template geometry" with ExtrudeGeometry using a dummy
10 sided polygon.
As before, created a bunch of "points", this time assigning each
point one of these template geometries.
On each frame, iterated through each geometry, updating each vertex
to that of the new one (using the voronoi alg as before).
If there are extra vertices left over, "bunch" them up into a single point. (see http://github.com/mrdoob/three.js/wiki/Updates.)
Looking at it now, it's quite a simple process. Before, the thought of manipulating each vertex seemed otherworldly to me, but it's not actually too tricky with simple shapes!
Here's how I did the iteration, polycColumn is just a 2 item array with the same polygon in each item:
// Set the vertex index
var v = 0;
// Iterate over both top and bottom of poly
for (var p=0;p<polyColumn.length;p++) {
// Iterate over half the vertices
for (var j=0;j<verts.length/2;j++) {
// create correct z-index depending on top/bottom
if (p == 1) {
var z = point.extrudeAmount;
} else {
var z = 0;
}
// If there are still legitimate verts
if (j < poly.length) {
verts[v].x = poly[j][0];
verts[v].y = poly[j][1];
verts[v].z = z;
// If we've got extra verts, bunch them up in the same place
} else {
verts[v].x = verts[v - 1].x;
verts[v].y = verts[v - 1].y;
verts[v].z = z;
}
v++;
}
}
point.mesh.geometry.verticesNeedUpdate = true;
I'm having an issue in my three.js code.
I am trying to align two objects by selecting two faces and have the second face (and object) rotate to match the normal vector of the first object's selected face.
So far I have:
var normalMatrix = new THREE.Matrix3().getNormalMatrix( object.matrixWorld );
var worldNormal = face.normal.clone().applyMatrix3( normalMatrix ).normalize();
var normalMatrixRef = new THREE.Matrix3().getNormalMatrix( objectRef.matrixWorld );
var worldNormalRef = faceRef.normal.clone().applyMatrix3( normalMatrixRef).normalize();
where: object is my object that will be rotated, face is the selected face of that object, objectRef is the stationary object reference and faceRef is the normal of the object I want to match.
Prior to doing
object.lookAt(worldNormalRef);
, I am trying either
object.up = new THREE.Vector3(0,0,1);
object.up = worldNormal;
object.up = face.normal;
and neither work.
Either object.up cases are not working as they should. When I do the action, the target object (the one to be rotated) does rotate, but does not align the faces correctly. It is arbitrary but somehow is linked to objects current rotation (ie: sometimes it rotates along (0,1,0) or simliar, othertimes if I pre-rotate the object it just rotates a slight bit.
In theory lookAt uses a world vector which my faceRef is, and as long as I set the 'up' correctly, it should work but it dosen't.
Any ideas?
I found the issue in my code, I hope it can help somebody in the future.
The
object.lookAt(worldNormalRef);
needs instead to be modified to add the new face normals to the current object's postition for the lookAt to function correctly:
//create a point to lookAt
var newPoint = new THREE.Vector3(
object.position.x + worldNormalRef.x,
object.position.y + worldNormalRef.y,
object.position.z + worldNormalRef.z
);
object.up = face.normal;//Z axis up
object.lookAt(newPoint );
Also note that the object.up should be set as above to the face.normal (the face I want to align to the reference object's face), and not to the worldNormal set above (I will delete this part of my code).