I am working on a program in three.js. So I have a particle system loaded from a LAS file. It has a coordinate system. I have added a functionality which enables user to click on a particle, and it would add a bounding box to the scene. My aim is to find which particles lie inside this bounding box.
Code for adding bounding box at point p clicked by user:
var cubeGeometry = new THREE.BoxGeometry( 1, 1, 1 );
var cubeMaterial = new THREE.MeshLambertMaterial( { color:
0xffff00,wireframe: true } );
var cube = new THREE.Mesh( cubeGeometry, cubeMaterial );
cube.position.x = p.x;
cube.position.y = p.y;
cube.position.z = p.z;
scene.add(cube);
But I am facing an issue. The box created has a different coordinate axis orientation than particle system. It's Y axis is oriented in direction of particle system's Z axis. This causes containsPoint method to give wrong answer.
How to solve this issue?
Try this:
var e = new THREE.Euler( - Math.PI / 2, 0, 0 );
p.applyEuler( e );
This will apply a rotation of 90 degrees around the x-axis or a conversion from Z-up to Y-up.
Related
What I'm trying to achieve is a rotation of the geometry around pivot point and make that the new definition of the geometry. I do not want te keep editing the rotationZ but I want to have the current rotationZ to be the new rotationZ 0.
This way when I create a new rotation task, it will start from the new given pivot point and the newly given rad.
What I've tried, but then the rotation point moves:
// Add cube to do calculations
var box = new THREE.Box3().setFromObject( o );
var size = box.getSize();
var offsetZ = size.z / 2;
o.geometry.translate(0, -offsetZ, 0)
// Do ratation
o.rotateZ(CalcUtils.degreeToRad(degree));
o.geometry.translate(0, offsetZ, 0)
I also tried to add a Group and rotate that group and then remove the group. But I need to keep the rotation without all the extra objects. The code I created
var box = new THREE.Box3().setFromObject( o );
var size = box.size();
var geometry = new THREE.BoxGeometry( 20, 20, 20 );
var material = new THREE.MeshBasicMaterial( { color: 0xcc0000 } );
var cube = new THREE.Mesh( geometry, material );
cube.position.x = o.position.x;
cube.position.y = 0; // Height / 2
cube.position.z = -size.z / 2;
o.position.x = 0;
o.position.y = 0;
o.position.z = size.z / 2;
cube.add(o);
scene.add(cube);
// Do ratation
cube.rotateY(CalcUtils.degreeToRad(degree));
// Remove cube, and go back to single object
var position = o.getWorldPosition();
scene.add(o)
scene.remove(cube);
console.log(o);
o.position.x = position.x;
o.position.y = position.y;
o.position.z = position.z;
So my question, how do I save the current rotation as the new 0 rotation point. Make the rotation final
EDIT
I added an image of what I want to do. The object is green. I have a 0 point of the world (black). I have a 0 point of the object (red). And I have rotation point (blue).
How can I rotate the object around the blue point?
I wouldn't recommend updating the vertices, because you'll run into trouble with the normals (unless you keep them up-to-date, too). Basically, it's a lot of hassle to perform an action for which the transformation matrices were intended.
You came pretty close by translating, rotating, and un-translating, so you were on the right track. There are some built-in methods which can help make this super easy.
// obj - your object (THREE.Object3D or derived)
// point - the point of rotation (THREE.Vector3)
// axis - the axis of rotation (normalized THREE.Vector3)
// theta - radian value of rotation
// pointIsWorld - boolean indicating the point is in world coordinates (default = false)
function rotateAboutPoint(obj, point, axis, theta, pointIsWorld){
pointIsWorld = (pointIsWorld === undefined)? false : pointIsWorld;
if(pointIsWorld){
obj.parent.localToWorld(obj.position); // compensate for world coordinate
}
obj.position.sub(point); // remove the offset
obj.position.applyAxisAngle(axis, theta); // rotate the POSITION
obj.position.add(point); // re-add the offset
if(pointIsWorld){
obj.parent.worldToLocal(obj.position); // undo world coordinates compensation
}
obj.rotateOnAxis(axis, theta); // rotate the OBJECT
}
After this method completes, the rotation/position IS persisted. The next time you call the method, it will transform the object from its current state to wherever your inputs define next.
Also note the compensation for using world coordinates. This allows you to use a point in either world coordinates or local space by converting the object's position vector into the correct coordinate system. It's probably best to use it this way any time your point and object are in different coordinate systems, though your observations may differ.
As a simple solution for anyone trying to quickly change the pivot point of an object, I would recommend creating a group and adding the mesh to the group, and rotating around that.
Full example
const geometry = new THREE.BoxGeometry();
const material = new THREE.MeshBasicMaterial({ color: 0xff0000 });
const cube = new THREE.Mesh(geometry, material);
scene.add(cube)
Right now, this will just rotate around its center
cube.rotation.z = Math.PI / 4
Create a new group and add the cube
const group = new THREE.Group();
group.add(cube)
scene.add(group)
At this point we are back where we started. Now move the mesh:
cube.position.set(0.5,0.5,0)
Then move the group
group.position.set(-0.5, -0.5, 0)
Now use your group to rotate the object:
group.rotation.z = Math.PI / 4
I am creating a solar system using three js.In that I want to display some of the details on clicking on any objects.I have used object picking concepts.In that I am trying to get the objects which are intersecting with the
clicking.But I am unable get any objects which are intersecting.When I tried to print the objects in the intersects array I am getting as "undefined" and length of the intersects array as 0.
function mous(event) {
var vector = new THREE.Vector3(( event.clientX / window.innerWidth ) * 2 - 1, -( event.clientY / window.innerHeight ) * 2 + 1, 0.5);
vector = vector.unproject(camera);
raycaster = new THREE.Raycaster(camera.position, vector);
var intersects = raycaster.intersectObjects([orbitDir1,orbitDir2,orbitDir3,orbitDir4,orbitDir5]);
alert(intersects[0]);
alert(intersects.length);
}`
And here is the code for orbitDir.
geometry = new THREE.CircleGeometry(2.3, 100);
geometry.vertices.shift();
circle = new THREE.Line(
geometry,
new THREE.LineDashedMaterial({color: 'red'})
);
circle.rotation.x = Math.PI * 0.5 ;
tex = new THREE.ImageUtils.loadTexture("Mercury.jpeg") ;
planet = new THREE.Mesh(
new THREE.SphereBufferGeometry(0.3, 32, 32),
new THREE.MeshPhongMaterial({ map : tex})
);
planet.position.set(2.3, 0, 0);
scene.add(planet);
orbit = new THREE.Group();
orbit.add(circle);
orbit.add(planet);
orbitDir = new THREE.Group();
orbitDir.add(orbit);
//orbitDir.position.x += 0.1 ;
orbitDir.position.y += 4 ;
orbitDir.position.z += 5 ;
orbitDir.rotation.x +=2.3 ;
scene.add(orbitDir);
The code for »unprojection« and raycasting look fine, so I guess that the x and y values might not be right. You are using clientX and clientY which are the mouse coordinates relative to the upper left corner of the window. Those are only valid if your <canvas> is full page. If that is not the case, make sure to use mouse coordinates relative to the upper left edge of the <canvas>.
I think you can do the raycasting like that:
raycaster.intersectObjects(scene, true) //scan the whole scene recursive
docs
Probably the answer you are looking for is here
projector.unprojectVector( vector, camera.position );
I´m very new to three js and I want to create a half Cylinder as roof.
var geometry = new THREE.CylinderGeometry(100,100,150);
var material = new THREE.MeshNormalMaterial();
var cylinder = new THREE.Mesh( geometry, material);
scene.add(cylinder);
This is the Basic Cylinder but unfortunately I couldn´t find an specific answer to a half cylinder yet.
Is it possible to create this with vertices?
The last 2 params of CylinderGeometry constructor allows this. For example:
var geometry = new THREE.CylinderGeometry(100,100,150, 8, 1, false, 0, Math.PI);
0 is the start angle and Math.PI is the end angle; i.e. half of a circle.
Is there a way to setup the Three.js renderer in such a way that the lookat point of the camera is not in the center of the rendered image?
To clarify: image a scene with just one 1x1x1m cube at ( 0, 0, 0 ). The camera is located at ( 0, 0, 10 ) and the lookat point is at the origin, coinciding with the center of the cube. If I render this scene as is, I might end up with something like this:
normal render
However I'd like to be able to render this scene in such a way that the lookat point is in the upper left corner, giving me something like this:
desired render
If the normal image is 800x600, then the result I envision would be as if I rendered a 1600x1200 image with the lookat in the center and then cropped that normal image so that only the lower right part remains.
Of course, I can change the lookat to make the cube go to the upper left corner, but then I view the cube under an angle, giving me an undesired result like this:
test.moobels.com/temp/cube_angle.jpg
I could also actually render the full 1600x1200 image and hide 3/4 of the image, but one would hope there is a more elegant solution. Does anybody know it?
If you want your perspective camera to have an off-center view, the pattern you need to use is:
camera = new THREE.PerspectiveCamera( for, aspect, near, far );
camera.setViewOffset( fullWidth, fullHeight, viewX, viewY, viewWidth, viewHeight );
See the docs: https://threejs.org/docs/#api/cameras/PerspectiveCamera
You can find examples of this usage in this example and this example.
three.js r.73
Here's a simple solution:
Assuming your cube is 4 x 4 x 4, at position 0, 0, 0:
var geometry = new THREE.BoxGeometry( 4, 4, 4 );
var material = new THREE.MeshBasicMaterial( { color: 0x777777 } );
var cube = new THREE.Mesh( geometry, material );
cube.position.set( 0, 0, 0 );
Get cube's position:
var Vx = cube.position.x,
Vy = cube.position.y,
Vz = cube.position.z;
Then deduct by 2 from x position, then add 2 to y and z position, and use the values to create a new Vector3:
var newVx = Vx - 2,
newVy = Vy + 2;
newVz = Vz + 2;
var xyz = new THREE.Vector3(newVx, newVy, newVz)
Then camera lookAt:
camera.lookAt(xyz);
Using console log, it would show that the camera is now looking at -2, 2, 2, which is the upper-left of your cube.
console.log(xyz);
I'm trying to make a static 3D prism out of point clouds with specific numbers of particles in each. I've got the the corner coordinates of each side of the prism based on the angle of turn, and tried spawning the particles in the area bound by these coordinates. Instead, the resulting point clouds have kept only the bottom left coordinate.
Screenshot: http://i.stack.imgur.com/uQ7Q8.png
I've tried to set the rotation of each cloud object such that their edges meet, but they will rotate only around the world centre. I gather this is something to do with rotation matrices and Euler angles, but, having been trying to work them out for 3 solid days, I've despaired. (I'm a sociologist, not a dev, and haven't touched graphics before this project.)
Please help? How do I set the rotation on each face of the prism? Or maybe there is a more sensible way to get the particles to spawn in the correct area in the first place?
The code:
// draw the particles
var n = 0;
do {
var geom = new THREE.Geometry();
var material = new THREE.PointCloudMaterial({size: 1, vertexColors: true, color: 0xffffff});
for (i = 0; i < group[n]; i++) {
if (geom.vertices.length < group[n]){
var particle = new THREE.Vector3(
Math.random() * screens[n].bottomrightback.x + screens[n].bottomleftfront.x,
Math.random() * screens[n].toprightback.y + screens[n].bottomleftfront.y,
Math.random() * screens[n].bottomrightfront.z + screens[n].bottomleftfront.z);
geom.vertices.push(particle);
geom.colors.push(new THREE.Color(Math.random() * 0x00ffff));
}
}
var system = new THREE.PointCloud(geom, material);
scene.add(system);
**// something something matrix Euler something?**
n++
}
while (n < numGroups);
I've tried to set the rotation of each cloud object such that their
edges meet, but they will rotate only around the world centre.
It is true they only rotate around 0,0,0. The simple solution then is to move the object to the center, rotate it, and then move it back to its original position.
For example (Code not tested so might take a bit of tweaking):
var m = new THREE.Matrix4();
var movetocenter = new THREE.Matrix4();
movetocenter.makeTranslation(-x, -y, -z);
var rotate = new THREE.Matrix4();
rotate.makeRotationFromEuler(); //Build your rotation here
var moveback = new THREE.Matrix4();
moveback .makeTranslation(x, y, z);
m.multiply(movetocenter);
m.multiply(rotate);
m.multiply(moveback);
//Now you can use geometry.applyMatrix(m)