Within my THREE scene i have an Object that rotates. The child object is positioned at (92,92,92) within the rotating Object, so it orbits the centre position (0,0,0) is a spherical path with my mouse movement. How can i find the global position of the child object in respect to the scene as it rotates. I'm fairly new to THREE.js and thankful for any support in advance.
My code:
ObjectParent = new THREE.Object3D();
scene.add( ObjectParent );
ObjectChild = new THREE.Object3D();
ObjectParent.add( ObjectChild );
ObjectChild.position.set(92,92,92);
Render:
ObjectParent.rotation.y -= (target.y + ObjectParent.rotation.y) * 0.08;
ObjectParent.rotation.x += (target.x - ObjectParent.rotation.x) * 0.07;
ObjectParent.updateMatrixWorld();
scene.updateMatrixWorld();
First of all, you usually do not need to call
ObjectParent.updateMatrixWorld();
scene.updateMatrixWorld();
inside your render loop. The renderer will do that for you.
To find the world position of a child object, you can use this pattern:
var vector = new THREE.Vector3();
...
vector.setFromMatrixPosition( child.matrixWorld );
The renderer should have previously updated the scene matrices for you. If you have changed a parent's position since the last rendering, you will have to first call
parent.updateMatrixWorld();
to update the relevant matrices.
It is a good idea to look at the three.js source code so you understand what these functions do.
three.js r.67
Related
I am trying to orbit a camera on an inclined orbit around a scene while the camera always points to the scene's origin. (Think of the camera rig installation for filming the bullet dodging scene in the first Matrix movie.)
The idea is to let the x-component of the mouse position on screen determine the position of the camera on the orbit. Hence, I created a dummy object whose position is changed in the mousemove-listener. The camera is attached to the dummy object, and the dummy object is attached to a pivot which creates the orbit inclination.
var pivot = new THREE.Object3D();
var cameraPos = new THREE.Object3D();
var camera = new THREE.PerspectiveCamera( 75, window.innerWidth / window.innerHeight, 0.1, 1000 );
cameraPos.add(camera);
pivot.rotation.y = Math.PI/4;
pivot.add(cameraPos)
I've put a minimal example together here: codepen.
The result is this erratic camera movement. Any idea WHY that happens?
I cannot figure out what I am doing wrong.
A solution
I will add that I know already how to fix it.
Step 1: Detach the camera from the dummy object cameraPos
Step 2: Set the camera position manually to the position cameraPos.
var target = new THREE.Vector3();
cameraPos.getWorldPosition(target)
camera.position.copy(target);
Outro
I really like the idea of attaching the camera to an object which follows then a prescribed path. But does attaching the camera to an object create unwanted interaction? What is the explanation for this behavior?
In Three.js, I have a group of meshes that is loaded from outside with help of FBX loader. The group has six meshes inside. My task is to make this meshes follow pointer when they get hovered. More precisely, I'd like to have a sort of magnetic effect (just like navbar items in this pen, but with meshes in Three.js).
I think, firstly, I have to detect, where currently pointer is, i.e. get position of cursor in world coordinates system, and then translate meshes towards it. But when I try to get the position of cursor, it seems to be wrong.
Having said that, I have two questions:
How to get proper cursor's position relative to the world coordinates?
How to change position of each of the group's meshes so that they get translated against the cursor?
Here is what have I done so far:
Hi everyone.
In Three.js, I have a group of meshes that is loaded from outside with help of FBX loader. The group has six meshes inside. My task is to make this meshes follow pointer when their canvas get hovered. More precisely, I'd like to have a sort of magnetic effect (just like navbar items in this pen, but with meshes of Three.js).
I think, firstly, I have to detect, where currently pointer on canvas is, i.e. get position of cursor in world coordinates system, and then translate meshes towards it. But when I try to get the position of cursor, it seems to be wrong.
Having said that, I have two questions:
How to get proper cursor's position relative to the world coordinates?
How to change position of each of the group's meshes so that they get translated against the cursor?
Here is what have I done so far. Function that translates meshes isn't written yet. Mousemove callback returns pretty big digits, though:
// Load object and play a third-party animation
loader.load("Object_001.fbx", (object) => {
mixer = new THREE.AnimationMixer(object);
const action = mixer.clipAction(object.animations[0]);
action.play();
object.traverse((child) => {
if (child.isMesh) {
child.material.map = texture;
child.material.needsUpdate = true;
}
});
scene.add(object);
});
// log coordinates of the pointer
const mouse = new THREE.Vector3();
const position = new THREE.Vector3();
function onMouseMove(event) {
mouse.set(
(event.clientX / window.innerWidth) * 2 - 1,
-(event.clientY / window.innerHeight) * 2 + 1,
0.5
);
mouse.unproject(camera);
mouse.sub(camera.position).normalize();
const distance = -camera.position.z / mouse.z;
position.copy(camera.position).add(mouse.multiplyScalar(distance));
console.log(position);
}
wrapperElement.addEventListener("mousemove", onMouseMove);
Thanks in advance.
Made a codepen here:
https://codepen.io/cdeep/pen/YzxPPZQ
The cursor only exists in the canvas dom element which is a rendering of the camera view frustum.
The easiest way to make the object follow a mouse is to get the point of intersection of the mouse with another object in the 3d scene and set the object position to the intersection point. The above codepen showcases that.
raycaster.setFromCamera( mouse, camera );
const intersects = raycaster.intersectObjects([ground]);
if(intersects.length) {
const { point } = intersects[0];
cube.position.copy(point.setY(0.5));
}
You could also position it at a fixed distance from the mouse but it looks odd in my opinion:
const distance = 10;
raycaster.setFromCamera( mouse, camera );
const { origin, direction } = raycaster.ray;
cube.position.copy(origin.clone().add(direction.multiplyScalar(distance)));
Documentation for raycaster:
https://threejs.org/docs/index.html?q=ray#api/en/core/Raycaster
Raycasting is used for mouse picking (working out what objects in the
3d space the mouse is over) amongst other things.
I'm rather new to threejs, so what I'm doing might not be the most efficient way.
I have an object in AR on a mobile device and I want to know if I intersect with it when touching on the screen.
I use the following code to generate the raycast, and it works initally.
const tempMatrix = new THREE.Matrix4();
tempMatrix.identity().extractRotation(this.controller.matrixWorld);
this.raycaster.ray.origin.setFromMatrixPosition(this.controller.matrixWorld);
this.raycaster.ray.direction.set(0, 0, -1).applyMatrix4(tempMatrix);
However, I have the ability to reposition the object (i.e. reset the position so the object is in front, relative to the current camera direction and position) by moving and rotating the whole scene.
After the repositioning, the raycasting is completely offset and is not casting rays anywhere near where I touch the screen.
Repositioning is done like this (while it works, if there's a better way, let me know!) :
public handleReposition(): void {
const xRotation = Math.abs(this.camera.rotation.x) > Math.PI / 2 ? -Math.PI : 0;
const yRotation = this.camera.rotation.y;
this.scene.rotation.set(xRotation, yRotation, xRotation);
this.scene.position.set(this.camera.position.x, this.camera.position.y, this.camera.position.z);
}
How can I achieve to raycast to the correct new location?
Thanks!
Assuming this.scene is actually the main threejs Scene, it's usually a bad idea to change its rotation or position, since it will affect everything inside the scene, including the controller. I'd suggest moving your object instead, or add your object(s) to a Group and move that.
I'm new in THREE.js.
I'm trying to get 3D coordinates of point on mouse click on the object (not simple objects: Box, Sphere,..) in Canvas.
In detail, I'm working with 3D objects viewer - I have camera (THREE.PerspectiveCamera), mouse controls (rotate, zoom, move), add/remove objects (my own object, loaded using loaders for THREE.js) in scene,.. And I want to add a function, which gets 3D coordinates for clicked point in 3D.
Exactly, I want coordinates of the end point of a ray - begining from mouse click on the camera_near_window and ending to the object's point, I've clicked on..
I tried a lot of ways to do it:
Getting coordinates of point on z=0 plane -- It works fine, but it is on z=0 plane and it is not that I need, cause I have OrbitControls..
THREE.js example - clickable objects -- It uses CanvasRenderer (not WebGLRenderer) and works for a little objects (but works for my project): browser crashes when I load many objects (CanvasRenderer needs 5x more memory then WebGLRenderer).
"How to get object in WebGL 3d space from a mouse click coordinate" - I tried this one too, but raycaster.intersectObjects found nothing, intersects was an empty array (maybe it works for only simple objects like box, sphere,..).
Can anyone show me the demo code which gets 3D point coords for clicked point of clicking object in 3D, please..?
So, as I think this question is useful for someone, I'll answer it myself (I'll write my resolve):
var renderer, canvas, canvasPosition, camera, scene, rayCaster, mousePosition;
function init() {
renderer = new THREE.WebGLRenderer({ antialias: false });
canvas = renderer.domElement;
canvasPosition = $(canvas).position();
camera = new THREE.PerspectiveCamera(20, $(canvas).width() / $(canvas).height(), 0.01, 1e10);
scene = new THREE.Scene();
rayCaster = new THREE.Raycaster();
mousePosition = new THREE.Vector2();
scene.add(camera);
var myObjects = new THREE.Object3D();
// myObjects.add( your object );
// myObjects.add( your object );
// myObjects.add( your object );
myObjects.name = 'MyObj_s';
scene.add(myObjects);
};
function getClicked3DPoint(evt) {
evt.preventDefault();
mousePosition.x = ((evt.clientX - canvasPosition.left) / canvas.width) * 2 - 1;
mousePosition.y = -((evt.clientY - canvasPosition.top) / canvas.height) * 2 + 1;
rayCaster.setFromCamera(mousePosition, camera);
var intersects = rayCaster.intersectObjects(scene.getObjectByName('MyObj_s').children, true);
if (intersects.length > 0)
return intersects[0].point;
};
I have some custom geometries obtained from a STEP file conversion and I use the mouse to rotate them. They rotate around the origin of the scene, but since they are far from it, they seem rotating on a virtual sphere. How can I move them to the origin so that they don't seem "floating" around (I mean that I'd like to reduce to zero the radius of the virtual sphere). This is the example I'd like to move. I've tried setting their position to (0, 0, 0) doing:
object.position.x = 0;
object.position.y = 0;
object.position.z = 0;
but it didin't work.
The typical solution to this problem is to translate the geometry right after it is created. You do that by applying a translation matrix to the geometry like so:
geometry.applyMatrix( new THREE.Matrix4().makeTranslation( distX, distY, distZ ) );
EDIT: You can simply do this, instead:
geometry.translate( distX, distY, distZ ); // three.js r.72
The function geometry.computeBoundingBox() may be of help to you in determining an amount to translate.
However, I see in your case, you have multiple geometries, so it it a bit more complicated, but doable. You will need to translate each geometry by the same amount.
EDIT
Tip: Instead of adding each object to the scene, create a parent object, add it to the scene, and then add the objects to the parent.
var parent;
parent = new THREE.Object3D();
scene.add( parent );
parent.add( object1 );
parent.add( object2 );
// and so on...
Then in your render function, just rotate the parent, not the individual objects.