I'm creating text labels that appear on a 3D cube using the following pattern:
canvas = createTextCanvas(text, color, font, size);
texture = new THREE.Texture(canvas);
geom = new THREE.PlaneBufferGeometry(canvas.width, canvas.height, segW, segH);
material = new THREE.MeshBasicMaterial({map: texture, transparent: true});
mesh = new THREE.Mesh(geom, material);
mesh.position.x = x;
mesh.position.y = y;
mesh.position.z = z;
texture.needsUpdate = true;
The labels and their positions get set within a for loop for each edge of the cube. This results in labels appearing similar to this:
But then when I rotate the cube (using OrbitControls), you'll see that the label no longer appears vertically like above:
So using the Cost label as an example, I would want the text to remain vertically oriented whenever the cube is rotated. Basically, I'm trying to mimic the behavior of axis labeling in VTK.
So I believe the solution here is to set the up vector of the label to a vector that's always orthogonal to the plane. But I'm not sure how to implement this. Any suggestions or examples would be greatly appreciated.
If it helps, I'm constructing the cube using a BoxGeometry and MeshNormalMaterial.
Do you mean the label keeps moving with the cube or not?
If not, there is a example: http://stemkoski.github.io/Three.js/Sprite-Text-Labels.html. The label keeps facing to you but may not vertical.
Else ,you may need a canvas texture,the label is a object just like the cube and you can set its position to keep it vertical.But it doesn't look good sometime.the example:http://stemkoski.github.io/Three.js/Texture-From-Canvas.html.
I think you just want the label always facing to you when you change your sight.
Related
Let's say I have a sort of rather simple terrain from Blender exported as GLB object, which is a Group and contains a Mesh with BufferGeometry. I have another GLB object which is a model of vehicle. How can I read proper position.y at specific x,z locations (idealy 4 locations for setting car position and rotation) without moving mouse and using raycaster? I need to know what is elevation and height at specific region. Any simple clue without game-physics engine on top of ThreeJS?
Just use a Raycaster. I don't know why you don't want to use it, it's the easiest way to find an intersection without a physics engine and without tons of math.
Simply use Raycaster.set() to point straight down from your XZ coords and see where it intersects the terrain:
var ray = new THREE.Raycaster();
var rayPos = new THREE.Vector3();
// Use y = 100 to ensure ray starts above terran
rayPos.set(x, 100, z);
var rayDir = new THREE.Vector3(0, -1, 0); // Ray points down
// Set ray from pos, pointing down
ray.set(rayPos, rayDir);
// Check where it intersects terrain Mesh
let intersect = ray.intersectObject(terrainMesh);
console.log(intersect);
See here for the intersect object. It includes the point in space where the intersection takes place.
I tried to rotate an object arount the Worlds-Y-Axis, with
myObject.rotateOnWorldAxis(new THREE.Vector3(0,1,0),THREE.Math.degToRad(1));
but the result was, that the object is only rotated in object space.
To be sure that I used the correct method I looked into the documentation and found that there are three methods to rotate an object:
.RotateY(rad) // rotate in Local Space
.rotateOnAxis(axis,rad) // rotation in Object Space
.rotateOnWorldAxis(axis,rad) // rotation in World Space
It seems that I used the correct method.
Is this a bug or an understanding problem on my side?
Here is a JSFiddle which illustrates my problem (the blue cube should rotate around the world axis).
Here is a second Fiddle where thy cyan cube is a child of another object.
It looks to me like your real question isn't regarding world space or object space rotations, cause those are working as expected in your examples.
You probably meant, how to change the point of rotation of an object. If that is the case, you have two options, you can either translate all your geometry vertices in respect to a pivot point of rotation. That way, your pivot will be centered at (0,0,0) and your vertices will rotate in respect to that.
mesh.geometry.translate( x, y, z );
Or you can make your object a child of a different Object3D (pivot), position your original mesh similarly to what was described above and rotate your pivot mesh.
var cube = new THREE.Mesh( geometry, material );
var pivot = new THREE.Object3D();
cube.position.set( 0, 12, 30 ); // offset from center
pivot.add( cube );
scene.add( pivot );
//...
pivot.rotation.y += Math.PI/2;
JSFiddle
I am dynamically adding a number of different objects of various sizes into a scene (one per click) and scaling and positioning them. Now I want to be able to rotate the objects around the Y axis at their center. I have added a boundingBox and an axesHelper, but the latter is showing up in the bottom corner of the objects. Reading this answer, which is similar to mine, it seems like this might be because of an offset. I can find the center of the object fine with this:
var box3 = new THREE.Box3();
var boundingBox = new THREE.BoxHelper( mesh, 0xffff00 );
scene.add( boundingBox );
box3.setFromObject( boundingBox );
center = box3.getCenter( boundingBox.position );
console.log( "center: ", center );
But when I try to reset the center to this position, following this answer, my object shoots way off into space.
box3.center(mesh.position);
mesh.position.multiplyScalar( -1 );
And I’m not really clear (even after reading the documentation) what “multiplyScalar” does/means. By playing with that number, I can get the object closer to the desired position, but the object still doesn't rotate around its center, and the AxesHelper is still at the original location.
Your object is not rotating around its center. Likely, your object's geometry is offset from the origin.
If you are dealing with a single Mesh or Line, you can center the object's geometry by calling
geometry.center();
This method will translate the vertices of the geometry so the geometry's bounding box is centered at the origin.
three.js r.97
Some project background:
I have a Sprite particle field that is randomly generated. The camera is located at position 0, 0, 0. The particle field is all around the camera. I'm using Raycaster to be able to select the particle that is clicked on and change it's color. Once clicked I would like the camera to focus on this particle. I'm also attempting to use Tween to glide the particle into view.
I've attempted several different methods and none of them work. They are described here:
A traditional lookAt method that used Raycaster to pick up the intersect point from clicking.
var raycaster = new THREE.Raycaster();
raycaster.setFromCamera(mouse, this.camera);
var intersects = raycaster.intersectObjects( this.starfield.children );
this.camera.lookAt(intersects[0].object.position)
A distanceTo method where the distance between the camera and the intersect coordinates is used to move the camera. This only moves the camera along the z plane. It wont actually change its POV.
var cameraPosition = new THREE.Vector3(this.camera.position.x, this.camera.position.y, this.camera.position.z);
var intersectPosition = new THREE.Vector3(intersects[0].object.position.x, intersects[0].object.position.y , intersects[0].object.position.z );
var zoomPos = intersectPosition.distanceTo( cameraPosition );
const newCameraPosition = cameraPosition.addVectors(this.camera.position, vector.setLength(zoomPos));
I calculated the angle of rotation for each X, Y, and Z axis via tan and cos equations. I then attempted to rotate the camera by those degrees. I even tried converting them to radians to see if that would make a difference with the rotation method. It didnt :(
I don't know what else to do. At this stage I'm completely open to a different approach as long as I get this camera working. I'm very stuck,
any help would be greatly appreciated!
Instead of using
intersects[0].object.position
try using
intersects[0].point
.point is the world space position of the hit.
.objectis the object the triangle belongs to. .object.position is just the origin of that object, in this case the particle system. The particle positions themselves are relative to this origin.
Is there any way to configure the camera in Three.js so that when a 2d object (line, plane, image) is rendered at z=0, it doesn't bleed (from perspective) into other pixels.
Ex:
var plane = new THREE.Mesh(new THREE.PlaneGeometry(1, 1), material);
plane.position.x = 4;
plane.position.y = 3;
scene.add(plane);
...
// Get canvas pixel information
context.readPixels(....);
If you example the data from readPixels, I always find that the pixel is rendering into its surrounding pixels (ex: 3,3,0 may contain some color information), but would like it to be pixel perfect if the element that is draw is on the z=0 plane.
You probably want to use THREE.OrthographicCamera for the 2d stuff instead of THREE.PerspectiveCamera. That way they are not affected by perspective projection.
Which pixels get rendered depends on where your camera is. If your camera for example t z=1 then a lot of pixels will get rendered. If you move your camera to z=1000 then you see, due to perspective, maybe only 1 pixel will get rendered from your geometry.