I'm new in Three.js, actually I'm trying to build a simple ring with and engraved text, for this purpose I would like to use a LatheGeometry (so no TubeGeometry or subtraction of two CylinderGeometries).
I build everything based on this examaple, but when I add the engraved text using a CSG subtraction (I use https://github.com/Sean-Bradley/THREE-CSGMesh/), I obtain a strange artifact in the outer face of the ring.
Bellow screens before and after the subtraction.
I already tried to increase the segment size, or change the geometry with computeFaceNormals and computeVertexNormals.
Below how I generate the LatheBufferGeometry and how I add the text.
var points = [];
points.push(new THREE.Vector2(5, 0.75));
points.push(new THREE.Vector2(5, -0.75));
points.push(new THREE.Vector2(6, -0.75));
points.push(new THREE.Vector2(6, 0.75));
points.push(new THREE.Vector2(5, 0.75));
const latheRingGeometry = new THREE.LatheBufferGeometry(points, 200, 0, 2 * Math.PI);
const latheRingMaterial = new THREE.MeshStandardMaterial({color: 0xffff00, side: THREE.DoubleSide});
const latheRingMesh = new THREE.Mesh( latheRingGeometry, latheRingMaterial );
And how to engrave text:
const bender = new Bender();
let engravedTextGeometry = new THREE.TextGeometry('TODO', {font: engravedTextFont, size: 1, height: 0.2, curveSegments: 2 })
engravedTextGeometry.center();
bender.bend(engravedTextGeometry, 'y', Math.PI / 16);
engravedTextGeometry.translate(0, 0, -5);
const textCSG = CSG.fromGeometry(engravedTextGeometry);
const engravedCSG = CSG.fromMesh(latheRingMesh).subtract(textCSG);
ring.geometry.dispose();
ring.geometry = CSG.toMesh(engravedCSG, new THREE.Matrix4()).geometry;
Result before apply subtraction
Result After apply subtraction
Related
EDIT: I solved my problem and this is what is was for. It now uses raw webgl and two triangles for each rectangle.
I'm a seasoned developer, but know next to nothing about 3d development.
I need to animate a million small rectangles where I set the coordinates in Javascript (rather than through a shader). (EDIT: It's a 2D job and I'm looking at webgl for performance reasons only.) I tweaked an existing threejs sample that uses "Points" to modify the coordinates in a BufferGeometry via Javascript and that performs really well, even with a million points.
The three.js concept of "Points", however, is a bit weird in that it appears they have to be squares - my rectangles can't be quite squares though, and they are of slightly different dimensions each.
I can think of a couple of workarounds, such as having foreground-colored squares partially overlap with squares of a background-color, thereby molding them into the correct rectangle. That's quite hacky though.
Another possibility would be to not do it with points but rather with proper triangles; but then I need to set 12 values from Javascript (2 triangles, 3 edges, 2 dimensions) rather than just the needed 4 (x, y, width, height). I suppose that could be improved with a vertex shader somehow, but that will be tricky for a noob like me.
I'm looking for some suggestions or, alternatively, a sample on how to set a large number of vertex coordinates from Javascript in threejs (the existing samples all appear to assume that manipulation is done in shaders, but that doesn't work so well for my use case).
EDIT - Here's a picture of how the rectangles could be laid out:
The rectangle's top and bottom edges are arbitrary, but they are organized into columns of arbitrary widths.
The rectangles of each column all have the same, uniform color.
Just an option with canvas and .map:
var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera(60, innerWidth / innerHeight, 1, 1000);
camera.position.set(0, 0, 10);
camera.lookAt(scene.position);
var renderer = new THREE.WebGLRenderer();
renderer.setSize(innerWidth, innerHeight);
document.body.appendChild(renderer.domElement);
var gh = new THREE.GridHelper(10, 10, "black", "black");
gh.rotation.x = Math.PI * 0.5;
gh.position.z = 0.01;
scene.add(gh);
var canvas = document.createElement("canvas");
var map = new THREE.CanvasTexture(canvas);
canvas.width = 512;
canvas.height = 512;
var ctx = canvas.getContext("2d");
ctx.fillStyle = "gray";
ctx.fillRect(0, 0, canvas.width, canvas.height);
function drawRectangle(x, y, width, height, color) {
let xUnit = canvas.width / 10;
let yUnit = canvas.height / 10;
let x_ = x * xUnit;
let y_ = y * yUnit;
let w_ = width * xUnit;
let h_ = height * yUnit;
ctx.fillStyle = color;
ctx.fillRect(x_, y_, w_, h_);
map.needsUpdate = true;
}
drawRectangle(1, 1, 4, 3, "aqua");
drawRectangle(0, 6, 6, 3, "magenta");
drawRectangle(3, 2, 6, 6, "yellow");
var plane = new THREE.Mesh(new THREE.PlaneBufferGeometry(10, 10), new THREE.MeshBasicMaterial({
color: "white",
map: map
}));
scene.add(plane);
renderer.setAnimationLoop(() => {
renderer.render(scene, camera);
});
body {
overflow: hidden;
margin: 0;
}
<script src="https://threejs.org/build/three.min.js"></script>
Read the source for these samples:
https://threejs.org/examples/?q=buffer#webgl_buffergeometry_custom_attributes_particles
https://threejs.org/examples/?q=buffer#webgl_buffergeometry_instancing
https://threejs.org/examples/?q=buffer#webgl_buffergeometry_instancing_billboards
https://threejs.org/examples/?q=buffer#webgl_buffergeometry_points
I seem to find only examples to use the raycaster with the camera, but none that just have a raycaster from Point A to Point B.
I have a working raycaster, it retrieves my Helpers, Lines etc. but it seems it does not recognize my sphere.
My first thought was my points are off, so i decided to create a line from my pointA to my pointB with a direction like so:
var pointA = new Vector3( 50, 0, 0 );
var direction = new Vector3( 0, 1, 0 );
direction.normalize();
var distance = 100;
var pointB = new Vector3();
pointB.addVectors ( pointA, direction.multiplyScalar( distance ) );
var geometry = new Geometry();
geometry.vertices.push( pointA );
geometry.vertices.push( pointB );
var material = new LineBasicMaterial( { color : 0xff0000 } );
var line = new Line( geometry, material );
This will show a line from my point (50 0 0) to (50 100 0) right trough my sphere which is at point (50, 50, 0) so my pointA and direction values are correct.
Next i add a raycaster:
To avoid conflicts with any side effects i recreated my points here:
var raycaster = new Raycaster(new Vector3( 50, 0, 0 ), new Vector3( 0, 1, 0 ).normalize());
var intersects = raycaster.intersectObject(target);
console.log(intersects);
Seems pretty straight forward to me, i also tried to use raycaster.intersectObjects(scene.children) but it gives Lines, helpers etc. but not my sphere.
What am i doing wrong? I am surely missing something here.
IMG of the line and the sphere:
What you see is explained in the following github issue:
https://github.com/mrdoob/three.js/issues/11449
The problem is that the ray emitted from THREE.Raycaster does not directly hit a face but its vertex which results in no intersection.
There are several workarounds to solve this issue e.g. slightly shift the geometry or the ray. For your case:
var raycaster = new THREE.Raycaster( new THREE.Vector3( 50, 0, 0 ), new THREE.Vector3( 0, 1, 0.01 ).normalize() );
However, a better solution is to fix the engine and make the test more robust.
Demo: https://jsfiddle.net/kzwmoug2/3/
three.js R106
I want to aim for objects with cameras' vision (as the user would look at the object, not point at it with mouse).
I'm casting a ray from the camera like this
rotation.x = camera.rotation.x;
rotation.y = camera.rotation.y;
rotation.z = camera.rotation.z;
raycaster.ray.direction.copy( direction ).applyEuler(rotation);
raycaster.ray.origin.copy( camera.position );
var intersections = raycaster.intersectObjects( cubes.children );
This gets me the intersections but it seems to wander off sometimes. So I'd like to add aim (crosshair). That would be somekind on object (mesh) at the end or in the middle of the ray.
How can I add it? When I created a regular line it was in front of the camera so the screen would go black.
You can add a crosshair constructed from simple geometry to your camera like this:
var material = new THREE.LineBasicMaterial({ color: 0xAAFFAA });
// crosshair size
var x = 0.01, y = 0.01;
var geometry = new THREE.Geometry();
// crosshair
geometry.vertices.push(new THREE.Vector3(0, y, 0));
geometry.vertices.push(new THREE.Vector3(0, -y, 0));
geometry.vertices.push(new THREE.Vector3(0, 0, 0));
geometry.vertices.push(new THREE.Vector3(x, 0, 0));
geometry.vertices.push(new THREE.Vector3(-x, 0, 0));
var crosshair = new THREE.Line( geometry, material );
// place it in the center
var crosshairPercentX = 50;
var crosshairPercentY = 50;
var crosshairPositionX = (crosshairPercentX / 100) * 2 - 1;
var crosshairPositionY = (crosshairPercentY / 100) * 2 - 1;
crosshair.position.x = crosshairPositionX * camera.aspect;
crosshair.position.y = crosshairPositionY;
crosshair.position.z = -0.3;
camera.add( crosshair );
scene.add( camera );
Three.js r107
http://jsfiddle.net/5ksydn6u/2/
In case you dont have a special usecase where you need to retrieve the position and rotation from your camera like you are doing, I guess your "wandering off" could be fixed by calling your raycaster with these arguments.:
raycaster.set( camera.getWorldPosition(), camera.getWorldDirection() );
var intersections = raycaster.intersectObjects( cubes.children );
Cast visible ray
Then you can visualize your raycast in 3D space by drawing an arrow with the arrow helper. Do this after your raycast:
scene.remove ( arrow );
arrow = new THREE.ArrowHelper( camera.getWorldDirection(), camera.getWorldPosition(), 100, Math.random() * 0xffffff );
scene.add( arrow );
(Please also refer to my illustration of the problem: http://i.stack.imgur.com/SfwwP.png)
problem description and ideas
I am creating several objects in the standard XYZ coordinate system.
Those are added to a THREE.group.
Please think of the group as a wall with several frames and image hung on it.
I want to create my frame objects with eg. dimension of (40, 20, 0.5). So I get a rather flat landscape formatted frame/artwork. I create and place several of those. Then I add them to the group, which I wanted to freely rotate in the world along two vectors start and end.
The problem I am struggling with is how to rotate and position the group from a given vector start to a give vector end.
So far I tried to solve it with a THREE.Matrix4().lookAt :
var group = new THREE.Group();
startVec = new THREE.Vector3( 100, 0, -100 );
endVec = new THREE.Vector3( -200, 0, 200 );
matrix = new THREE.Matrix4().lookAt(startVec, endVec, new THREE.Vector3( 0, 1, 0 ));
group.matrixAutoUpdate = false;
var object1 = new THREE.Mesh(new THREE.BoxGeometry(0.5, 20, 40), mat);
// etc. -> notice the swapping of X and Z coordinates I have to do.
group.add(object1);
group.applyMatrix(matrix);
You can see the example on jsfiddle:
http://jsfiddle.net/y6b9Lumw/1/
If you open jsfiddle, you can see that the objects are not placed along the line from start to end, although I their are placed along the groups internal X-Axis like: addBox(new THREE.Vector3( i * 30, 0 , 0 ));
Full code:
<html>
<head>
<title>testing a rotation matrix</title>
<style>body { margin: 0; } canvas { width: 100%; height: 100% } </style>
</head> <body>
<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r70/three.min.js"></script>
<script>
var scene, camera, renderer, light, matrix;
var startVec, endVec;
var boxes;
function addBox(v) {
var boxmesh;
var boxgeom = new THREE.BoxGeometry( 15, 5, 1 );
var boxmaterial = new THREE.MeshLambertMaterial( {color: 0xdd2222} );
boxmesh = new THREE.Mesh( boxgeom, boxmaterial );
//boxmesh.matrix.makeRotationY(Math.PI / 2);
boxmesh.matrix.setPosition(v);
boxmesh.matrixAutoUpdate = false;
boxes.add(boxmesh);
}
function init() {
renderer = new THREE.WebGLRenderer();
renderer.setClearColor( 0x222222 );
renderer.setPixelRatio( window.devicePixelRatio );
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );
scene = new THREE.Scene();
camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 1, 1000 );
camera.position.set( -20, 30, 300 );
var light = new THREE.PointLight (0xCCCCCC, 0.5 );
scene.add(light);
startVec = new THREE.Vector3( 100, 0, -100 );
endVec = new THREE.Vector3( -200, 0, 200 );
matrix = new THREE.Matrix4().lookAt(startVec, endVec, new THREE.Vector3( 0, 1, 0 ));
boxes = new THREE.Group();
for (var i = -100; i < 100; i++) {
addBox(new THREE.Vector3( i * 30, 0 , 0 ));
}
boxes.matrixAutoUpdate = false;
boxes.applyMatrix(matrix);
scene.add(boxes);
var linegeometry = new THREE.Geometry();
linegeometry.vertices.push( startVec, endVec);
var line = new THREE.Line(linegeometry, new THREE.LineBasicMaterial({color: 0x33eeef}));
scene.add(line);
render();
}
function render(){
requestAnimationFrame(render);
renderer.render(scene, camera);
}
init();
</script>
</body> </html>
This works only nicely to some extend. As the look vector is usually oriented along the Z-Axis (i think it is (0,0,1)). So unfortunately the objects inside the group get rotated like that aswell.
This is actually what you would expect from a lookAt() rotational transformation. It's not what I would like to have though, as this places all the children in the group, on their Z-Axis, instead of their X-Axis.
In order to have things look properly I had to initialize my groups children with X and Z swapped.
Instead of:
var object1 = new THREE.BoxGeometry( 40, 20, 0.5 );
I have to do:
var object1 = new THREE.BoxGeometry( 0.5, 20, 40 );
same if I want to translate objects in the group on the X-Axis, I have to use the Z-Axis, as that is the look-vector along which the whole wall is oriented by the matrix transformation.
my question is:
How does my matrix have to be constructed/look like to accomplish what I want: Normally create objects, and then have their X-Axis placed along vector start and vector end, like placing artworks on a wall, which can be moved around?
I thought about creating a matrix, whose X-Axis is end.sub(start), so the vector from start end end, might this be what I need to do? If so, how would I construct it?
problem illustration with an image
I tried to illustrate my sitation in two images. One being the wall, one being the wall inside the world, with the same objects attached to the wall (see top of the post).
In the first figure you see the local coordinate system of the group, with two added children, one translated along X.
In the second figure, you can see the same localsystem inside the world how I would like it to be. The green axes are the world axes. The start and end vectors are shown aswell. You can see, both boxes, are properly placed along that line.
I would like to answer my own question by disregarding the idea of manipulating the matrix myself. Thx to #WestLangley I adapted my idea to the following by setting the groups quaternion via .setFromUnitVectors.
So the rotation is derived from the rotation from the x-axis to the direction vector of start and end, as explained in three.js' documentation:
"Sets this quaternion to the rotation required to rotate direction vector vFrom to direction vector vTo."
(http://threejs.org/docs/#Reference/Math/Quaternion.setFromUnitVectors)
Below is the relevant part of my solution:
// define the starting and ending vector of the wall
start = new THREE.Vector3( -130, -40, 300 );
end = new THREE.Vector3( 60, 20, -100 );
// dir is the direction from start to end, normalized
var dir = new THREE.Vector3().copy(end).sub(start).normalize();
// position wall in the middle of start and end
var middle = new THREE.Vector3().copy(start).lerp(end, 0.5);
wall.position.copy(middle);
// rotate wall by applying rotation from X-Axis to dir
wall.quaternion.setFromUnitVectors( new THREE.Vector3(1, 0, 0), dir );
The result can be seen here: http://jsfiddle.net/L9dmqqvy/1/
(new to stackoverflow, new to webgl/three.js, ...)
I'm using three.js r54 to plot a force-directed graph. the edges between the nodes are THREE.Lines, which is fine, but lines are not selectable with a raycaster. so my aim is to take cylinders instead(/along with) of lines(also because I can do some further stuff: using textures,...)
this is what I'm doing to place the cylinders:
// init reference vector
var upVec = new THREE.Vector3(0,1,0);
//---withhin a loop---
// get direction
var direction = startPoint.subSelf(endPoint).clone();
// half length for cylinder height
var halfLength = direction.length() * 0.5;
// get offset
var offset = endPoint.clone().addSelf(direction.clone().multiplyScalar(0.5));
// normalize direc
direction.normalize();
//newUpVec = upVec - (upVec *(dot) direction) * direction - projection of direction
var newUpVec = upVec.clone().subSelf(direction.clone().multiplyScalar(upVec.dot(direction.clone()))).normalize();
var right = newUpVec.clone().crossSelf(direction.clone());
//build rotation matrix
var rot = new THREE.Matrix4(right.x, right.y, right.z, 0,
newUpVec.x, newUpVec.y, newUpVec.z, 0,
direction.x, direction.y, direction.z,0,
0,0,0,1);
//build translation matrix
var transla = new THREE.Matrix4(1, 0, 0, offset.x,
0, 1, 0, offset.y,
0, 0, 1, offset.z,
0, 0, 0, 1);
//build transformation matrix
var transfo = new THREE.Matrix4().multiply(transla, rot);
// create geometry
var cylgeo = new THREE.CylinderGeometry(2, 2, halfLength * 2, 12, 1, false);
cylgeo.applyMatrix(transfo);
var cylMesh = new THREE.Mesh(cylgeo, new THREE.MeshLambertMaterial({color:0x000000,
wireframe: true, shading: THREE.FlatShading}));
(descripted in: http://www.fastgraph.com/makegames/3drotation/ )
So the cylinders are placed at the right offset and align in some kind of way, but not to the two points (start, end) of the edges.
any suggestion would be appreciated!
using that :
object3d-rotation-to-align-to-a-vector
given 2 Vector3 and a scene:
function drawCylinder(vstart, vend,scene){
var HALF_PI = +Math.PI * .5;
var distance = vstart.distanceTo(vend);
var position = vend.clone().addSelf(vstart).divideScalar(2);
var material = new THREE.MeshLambertMaterial({color:0x0000ff});
var cylinder = new THREE.CylinderGeometry(10,10,distance,10,10,false);
var orientation = new THREE.Matrix4();//a new orientation matrix to offset pivot
var offsetRotation = new THREE.Matrix4();//a matrix to fix pivot rotation
var offsetPosition = new THREE.Matrix4();//a matrix to fix pivot position
orientation.lookAt(vstart,vend,new THREE.Vector3(0,1,0));//look at destination
offsetRotation.rotateX(HALF_PI);//rotate 90 degs on X
orientation.multiplySelf(offsetRotation);//combine orientation with rotation transformations
cylinder.applyMatrix(orientation)
var mesh = new THREE.Mesh(cylinder,material);
mesh.position=position;
scene.add(mesh);
}
r58+ code :
function drawCylinder(vstart, vend,scene){
var HALF_PI = Math.PI * .5;
var distance = vstart.distanceTo(vend);
var position = vend.clone().add(vstart).divideScalar(2);
var material = new THREE.MeshLambertMaterial({color:0x0000ff});
var cylinder = new THREE.CylinderGeometry(10,10,distance,10,10,false);
var orientation = new THREE.Matrix4();//a new orientation matrix to offset pivot
var offsetRotation = new THREE.Matrix4();//a matrix to fix pivot rotation
var offsetPosition = new THREE.Matrix4();//a matrix to fix pivot position
orientation.lookAt(vstart,vend,new THREE.Vector3(0,1,0));//look at destination
offsetRotation.makeRotationX(HALF_PI);//rotate 90 degs on X
orientation.multiply(offsetRotation);//combine orientation with rotation transformations
cylinder.applyMatrix(orientation)
var mesh = new THREE.Mesh(cylinder,material);
mesh.position=position;
scene.add(mesh);
}
#jdregister's answer didn't quite work for me in R77, since the cylinder ended up with its center at vstart (rotation and lookAt were otherwise fine).
This modification to the second last line of the R58+ answer did the trick:
mesh.position.set(position.x, position.y, position.z);
There's a very succinct answer here: https://stackoverflow.com/a/44346439/1556416
I paraphrased it here:
function drawCylinder(vstart, vend, radius){
var cylLength = new THREE.Vector3().subVectors(vend, vstart).length();
var cylGeom = new THREE.CylinderGeometry(radius, radius, cylLength, 16);
cylGeom.translate(0, cylLength / 2, 0);
cylGeom.rotateX(Math.PI / 2);
var material = new THREE.MeshLambertMaterial({color: "blue"})
var cyl = new THREE.Mesh(cylGeom, material);
cyl.position.copy(vstart);
cyl.lookAt(vend); // and do the trick with orienation
return cyl
}
In R87 the "vend.clone().add(vstart).divideScalar(2);" is not working
You can position the item like this
mesh.position.copy(start);
mesh.position.lerp(end, 0.5);
All the others from R58 are fine :)