Develop Reference

Trim interpolated polyline where terrain is intersecting in Cesium

I'm trying to create an arc which will stop when it intersects terrain. Two variables arc1 and arc2 where arc1 is without terrain intersection and arc2 is with terrain intersection.
arc1 is working properly but arc2 is not stopping where it intersects the terrain.
var viewer = new Cesium.Viewer("cesiumContainer", {
infoBox: false, //Disable InfoBox widget
selectionIndicator: false, //Disable selection indicator
shouldAnimate: true, // Enable animations
terrainProvider: Cesium.createWorldTerrain(),
});
//Enable lighting based on the sun position
viewer.scene.globe.enableLighting = true;
//Enable depth testing so things behind the terrain disappear.
viewer.scene.globe.depthTestAgainstTerrain = true;
// Cartesian3: start, mid and end points for polyline
var controls = [{x:-1942111.383043348,y:-4780646.881480431,z:3737538.9114379627},
{x:-1847333.0834675943,y:-5281519.814050422,z:3579120.5547780637},
{x:-1611854.2607850158,y:-5380130.367796415,z:3146339.4631628506}];
// Applying interpolation
var spline = Cesium.HermiteSpline.createNaturalCubic({
times: [0.0, 0.5, 1],
points: controls,
});
var ppos = []; //Interpolated polyline cordinates
for (var i = 0; i <= 50; i++) {
var cartesian3 = spline.evaluate(i / 50);
ppos.push(cartesian3);
}
/* Terrain and Polyline Intersection Detection */
var cartographic = [];
var cartographic_real = [];
ppos.forEach(p => {
let dh = Cesium.Cartographic.fromCartesian(p);
dh.height = 0;
cartographic.push(dh);
cartographic_real.push(Cesium.Cartographic.fromCartesian(p));
});
// collecting actual terrain heights
Cesium.sampleTerrainMostDetailed(viewer.terrainProvider, cartographic).then((raisedPositionsCartograhpic) => {
var t = true;
var rpos = []; //
cartographic_real.forEach((p, i) => {
if(t) rpos.push(ppos[i]);
// If terrain height is more than polyline cordinate height
if (i > 0 && t && (raisedPositionsCartograhpic[i].height - p.height)) {
t = false;
console.log("Stopped at:", p.height);
console.log(rpos);
drawNewArc(rpos);
}
});
});
/* --- */
function drawNewArc(rpos)
{
var arc1 = {};
arc1.polyline = { // Actual line without terrain intersection
positions: ppos,
width: 3,
material: Cesium.Color.RED.withAlpha(0.5),
}
var arc2 = {};
arc2.polyline = { // This should stop where it intersects terrain
positions: rpos,
width: 3,
material: Cesium.Color.GREEN.withAlpha(1.0),
}
var entity = viewer.entities.add(arc1);
var entity2 = viewer.entities.add(arc2);
}
viewer.camera.flyTo({destination: Cesium.Cartesian3.fromDegrees(-112.081,36.097,10000)});
I want the Green polyline to stop when it hits any terrain.
example
I think I need to get and match all the points of the arc. I don't know how to get all the points of the Green arc.
Here is the complete code link in sandcastle:

Got Success after repairing various mistakes in the code like:
Polyline segmentation was incorrect:
for (var i = 0; i <= 50; i++) {
Height matching condition was not correct:
if (i > 0 && t && (raisedPositionsCartograhpic[i].height - p.height)) {
Here is the complete working code link . It can also have mistakes and there must be a better solution to achieve the objective. If someone has any better and fast solution, please kindly post here.

Threejs Particle System with joining lines. Programming logic?

Based on a previous question I had recently posted:
How to create lines between nearby particles in ThreeJS?
I was able to create individual lines joining nearby particles. However, the lines are being drawn twice because of the logic of the particle system. This is because of how the original 2D particle system worked:
https://awingit.github.io/particles/
This also draws the lines twice. For each pair of particles connecting a line, the line is drawn.
I do not think this is ideal for performance. How would I only draw a line once for each joining points?
P.S. Here is exactly the effect I would like to achieve, but cannot make sense of the code:
http://freelance-html-developer.com/clock/
I would like to understand the fundamental logic.
UPDATE:
I have created a jsfiddle with my progress.
var canvas, canvasDom, ctx, scene, renderer, camera, controls, geocoder, deviceOrientation = false;
var width = 800,
height = 600;
var particleCount = 20;
var pMaterial = new THREE.PointsMaterial({
color: 0x000000,
size: 0.5,
blending: THREE.AdditiveBlending,
//depthTest: false,
//transparent: true
});
var particles = new THREE.Geometry;
var particleSystem;
var line;
var lines = {};
var lineGroup = new THREE.Group();
var lineMaterial = new THREE.LineBasicMaterial({
color: 0x000000,
linewidth: 1
});
var clock = new THREE.Clock();
var maxDistance = 15;
function init() {
canvasDom = document.getElementById('canvas');
setupStage();
setupRenderer();
setupCamera();
setupControls();
setupLights();
clock.start();
window.addEventListener('resize', onWindowResized, false);
onWindowResized(null);
createParticles();
scene.add(lineGroup);
animate();
}
function setupStage() {
scene = new THREE.Scene();
}
function setupRenderer() {
renderer = new THREE.WebGLRenderer({
canvas: canvasDom,
logarithmicDepthBuffer: true
});
renderer.setSize(width, height);
renderer.setClearColor(0xfff6e6);
}
function setupCamera() {
camera = new THREE.PerspectiveCamera(70, width / height, 1, 10000);
camera.position.set(0, 0, -60);
}
function setupControls() {
if (deviceOrientation) {
controls = new THREE.DeviceOrientationControls(camera);
controls.connect();
} else {
controls = new THREE.OrbitControls(camera, renderer.domElement);
controls.target = new THREE.Vector3(0, 0, 0);
}
}
function setupLights() {
var light1 = new THREE.AmbientLight(0xffffff, 0.5); // soft white light
var light2 = new THREE.PointLight(0xffffff, 1, 0);
light2.position.set(100, 200, 100);
scene.add(light1);
scene.add(light2);
}
function animate() {
requestAnimationFrame(animate);
controls.update();
animateParticles();
updateLines();
render();
}
function render() {
renderer.render(scene, camera);
}
function onWindowResized(event) {
width = window.innerWidth;
height = window.innerHeight;
camera.aspect = width / height;
camera.updateProjectionMatrix();
renderer.setSize(width, height);
}
function createParticles() {
for (var i = 0; i < particleCount; i++) {
var pX = Math.random() * 50 - 25,
pY = Math.random() * 50 - 25,
pZ = Math.random() * 50 - 25,
particle = new THREE.Vector3(pX, pY, pZ);
particle.diff = Math.random() + 0.2;
particle.default = new THREE.Vector3(pX, pY, pZ);
particle.offset = new THREE.Vector3(0, 0, 0);
particle.velocity = {};
particle.velocity.y = particle.diff * 0.5;
particle.nodes = [];
particles.vertices.push(particle);
}
particleSystem = new THREE.Points(particles, pMaterial);
particleSystem.position.y = 0;
scene.add(particleSystem);
}
function animateParticles() {
var pCount = particleCount;
while (pCount--) {
var particle = particles.vertices[pCount];
var move = Math.sin(clock.getElapsedTime() * (1 * particle.diff)) / 4;
particle.offset.y += move * particle.velocity.y;
particle.y = particle.default.y + particle.offset.y;
detectCloseByPoints(particle);
}
particles.verticesNeedUpdate = true;
particleSystem.rotation.y += 0.01;
lineGroup.rotation.y += 0.01;
}
function updateLines() {
for (var _lineKey in lines) {
if (!lines.hasOwnProperty(_lineKey)) {
continue;
}
lines[_lineKey].geometry.verticesNeedUpdate = true;
}
}
function detectCloseByPoints(p) {
var _pCount = particleCount;
while (_pCount--) {
var _particle = particles.vertices[_pCount];
if (p !== _particle) {
var _distance = p.distanceTo(_particle);
var _connection = checkConnection(p, _particle);
if (_distance < maxDistance) {
if (!_connection) {
createLine(p, _particle);
}
} else if (_connection) {
removeLine(_connection);
}
}
}
}
function checkConnection(p1, p2) {
var _childNode, _parentNode;
_childNode = p1.nodes[particles.vertices.indexOf(p2)] || p2.nodes[particles.vertices.indexOf(p1)];
if (_childNode && _childNode !== undefined) {
_parentNode = (_childNode == p1) ? p2 : p1;
}
if (_parentNode && _parentNode !== undefined) {
return {
parent: _parentNode,
child: _childNode,
lineId: particles.vertices.indexOf(_parentNode) + '-' + particles.vertices.indexOf(_childNode)
};
} else {
return false;
}
}
function removeLine(_connection) {
// Could animate line out
var childIndex = particles.vertices.indexOf(_connection.child);
_connection.parent.nodes.splice(childIndex, 1);
deleteLine(_connection.lineId);
}
function deleteLine(_id) {
lineGroup.remove(lines[_id]);
delete lines[_id];
}
function addLine(points) {
var points = points || [new THREE.Vector3(Math.random() * 10, Math.random() * 10, Math.random() * 10), new THREE.Vector3(0, 0, 0)];
var _lineId = particles.vertices.indexOf(points[0]) + '-' + particles.vertices.indexOf(points[1]);
var lineGeom = new THREE.Geometry();
if (!lines[_lineId]) {
lineGeom.dynamic = true;
lineGeom.vertices.push(points[0]);
lineGeom.vertices.push(points[1]);
var curLine = new THREE.Line(lineGeom, lineMaterial);
curLine.touched = false;
lines[_lineId] = curLine;
lineGroup.add(curLine);
return curLine;
} else {
return false;
}
}
function createLine(p1, p2) {
p1.nodes[particles.vertices.indexOf(p2)] = p2;
addLine([p1, p2]);
}
$(document).ready(function() {
init();
});
I am really close, but I am not sure if its optimized. There seem to be flickering lines, and sometimes a line just stays stuck in place.
So here are my thoughts. I clicked that all I have to do is make the Vector3 points of the lines equal to the relevant particle Vector3 points. I just need to update each lines geometry.verticesNeedUpdate = true;
Also, how I manage the lines is I create a unique ID using the indexes of the 2 points, e.g. lines['8-2'] = line

The problem you're actually trying to solve is that while looping through your list of points, you're doubling the number of successful matches.
Example:
Consider a list of points, [A, B, C, D]. Your looping tests each point against all other points. For this example, A and C are the only points close enough to be considered nearby.
During the first iteration, A vs. all, you find that A and C are nearby, so you add a line. But when you're doing your iteration for C, you also find that A is nearby. This causes the second line, which you want to avoid.
Fixing it:
The solution is simple: Don't re-visit nodes you already checked. This works because the answer of distance from A to C is no different from distance from C to A.
The best way to do this is adjust your indexing for your check loop:
// (Note: This is example code, and won't "just work.")
for(var check = 0, checkLength = nodes.length; check < checkLength; ++check){
for(var against = check + 1, against < checkLength; ++against){
if(nodes[check].distanceTo(nodes[against]) < delta){
buildThatLine(nodes[check], nodes[against]);
}
}
}
In the inner loop, the indexing is set to:
Skip the current node
Skip all nodes before the current node.
This is done by initializing the inner indexing to the outer index + 1.
Caveat:
This particular logic assumes that you discard all your lines for every frame. It's not the most efficient way to achieve the effect, but I'll leave making it more efficient as an exercise for you.

BoxGeometry not aligning with SphereGeometry properly

I am trying to create spikes on earth(sphere geometry). Though everything works fines, but spikes dont align with globe. I want spike to align something like below image. But my spikes dont lookAt(new THREE.Vector3(0,0,0)) despite mentioned. Please help me out.
I purposefully mentioned code required for debugging. Let me know if you need more code for this. Below image is how i want my spikes to align with sphere.
But this is how it looks
My Main JS initialization file.
$(document).ready(function () {
// Initializing Camera
Influx.Camera = new Influx.Camera({
fov: 60,
aspectRatio: window.innerWidth / window.innerHeight,
near: 1,
far: 1000,
position: {
x: 0,
y: 0,
z: 750
}
});
//Initializing Scene
Influx.Scene = new Influx.Scene();
// Initializing renderer
Influx.Renderer = new Influx.Renderer({
clearColor: 0x000000,
size: {
width: window.innerWidth,
height: window.innerHeight
}
});
Influx.Globe = new Influx.Globe({
radius: 300,
width: 50,
height: 50
});
//
Influx.Stars = new Influx.Stars({
particleCount: 15000,
particle: {
color: 0xFFFFFF,
size: 1
}
});
Influx.moveTracker = new Influx.moveTracker();
Influx.EventListener = new Influx.EventListener();
(function animate() {
requestAnimationFrame( animate );
render();
controls.update();
})();
function render() {
camera.lookAt(scene.position);
group.rotation.y -= 0.001;
renderer.render( scene, camera );
};
});
Below is code responsible for generating spikes on Globe.
Influx.Spikes = function (lat, long) {
// convert the positions from a lat, lon to a position on a sphere.
var latLongToVector3 = function(lat, lon, RADIUS, heigth) {
var phi = (lat) * Math.PI/180,
theta = (lon-180) * Math.PI/180;
var x = -(RADIUS+heigth) * Math.cos(phi) * Math.cos(theta),
y = (RADIUS+heigth) * Math.sin(phi),
z = (RADIUS+heigth) * Math.cos(phi) * Math.sin(theta);
return new THREE.Vector3(x, y, z);
};
var geom = new THREE.Geometry();
var BoxGeometry = new THREE.BoxGeometry(1, 100, 1);
//iterates through the data points and makes boxes with the coordinates
var position = latLongToVector3(lat, long, 300, 2);
var box = new THREE.Mesh( BoxGeometry );
//each position axis needs to be set separately, otherwise the box
//will instantiate at (0,0,0)
box.position.x = position.x;
box.position.y = position.y;
box.position.z = position.z;
box.lookAt(new THREE.Vector3(0, 0, 0));
box.updateMatrix();
//merges the geometry to speed up rendering time, don't use THREE.GeometryUtils.merge because it's deprecated
geom.merge(box.geometry, box.matrix);
var total = new THREE.Mesh(geom, new THREE.MeshBasicMaterial({
color: getRandomColor(),
morphTargets: true
}));
function getRandomColor() {
var letters = '0123456789ABCDEF';
var color = '#';
for (var i = 0; i < 6; i++ ) {
color += letters[Math.floor(Math.random() * 16)];
}
return color;
};
//add boxes to the group
group.add(total);
scene.add(group);
};
Influx.Camera = function(params = {}) {
if ( !$.isEmptyObject(params) ) {
window.camera = new THREE.PerspectiveCamera(params.fov, params.aspectRatio, params.near, params.far);
camera.position.set(params.position.x, params.position.y, params.position.z);
camera.lookAt(new THREE.Vector3(0,0,0));
} else {
console.log("Trouble with Initializing Camera");
return;
}
};

Remember that lookAt takes a direction vector, you give to this method the vector (0, 0, 0), this is actually not a normalized direction vector. So you must calculate the direction:
from your box position to the center of the sphere AND normalize it.
var dir = box.position.sub(world.position).normalize();
box.lookAt(dir);
And now just a set of code good conventions that may help you:
var BoxGeometry = new THREE.BoxGeometry(1, 100, 1);
Here I would rather use another var name for the box geometry, not to mix up with the "class" definition from THREE and to follow naming conventions:
var boxGeometry = new THREE.BoxGeometry(1, 100, 1);
And here:
box.position.x = position.x;
box.position.y = position.y;
box.position.z = position.z;
You can just set:
box.position.copy(position);

I also meet this problem, and I fixed it, the solution is: box.lookAt(new THREE.Vector3(0, 0, 0)) must after box.scale.z = xxxx

Incrementally display three.js TubeGeometry

I am able to display a THREE.TubeGeometry figure as follows
Code below, link to jsbin
<html>
<body>
<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r75/three.js"></script>
<script>
// global variables
var renderer;
var scene;
var camera;
var geometry;
var control;
var count = 0;
var animationTracker;
init();
drawSpline();
function init()
{
// create a scene, that will hold all our elements such as objects, cameras and lights.
scene = new THREE.Scene();
// create a camera, which defines where we're looking at.
camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
// create a render, sets the background color and the size
renderer = new THREE.WebGLRenderer();
renderer.setClearColor('lightgray', 1.0);
renderer.setSize(window.innerWidth, window.innerHeight);
// position and point the camera to the center of the scene
camera.position.x = 0;
camera.position.y = 40;
camera.position.z = 40;
camera.lookAt(scene.position);
// add the output of the renderer to the html element
document.body.appendChild(renderer.domElement);
}
function drawSpline(numPoints)
{
var numPoints = 100;
// var start = new THREE.Vector3(-5, 0, 20);
var start = new THREE.Vector3(-5, 0, 20);
var middle = new THREE.Vector3(0, 35, 0);
var end = new THREE.Vector3(5, 0, -20);
var curveQuad = new THREE.QuadraticBezierCurve3(start, middle, end);
var tube = new THREE.TubeGeometry(curveQuad, numPoints, 0.5, 20, false);
var mesh = new THREE.Mesh(tube, new THREE.MeshNormalMaterial({
opacity: 0.9,
transparent: true
}));
scene.add(mesh);
renderer.render(scene, camera);
}
</script>
</body>
</html>
However, I would like to display incrementally, as in, like an arc that is loading, such that it starts as the start point, draws incrementally and finally looks the below arc upon completion.
I have been putting in some effort, and was able to do this by storing all the points/coordinates covered by the arc, and drawing lines between the consecutive coordinates, such that I get the 'arc loading incrementally' feel. However, is there a better way to achieve this? This is the link to jsbin
Adding the code here as well
<!DOCTYPE html>
<html>
<head>
<title>Incremental Spline Curve</title>
<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r75/three.js"></script>
<style>
body {
margin: 0;
overflow: hidden;
}
</style>
</head>
<script>
// global variables
var renderer;
var scene;
var camera;
var splineGeometry;
var control;
var count = 0;
var animationTracker;
// var sphereCamera;
var sphere;
var light;
function init() {
// create a scene, that will hold all our elements such as objects, cameras and lights.
scene = new THREE.Scene();
// create a camera, which defines where we're looking at.
camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
// create a render, sets the background color and the size
renderer = new THREE.WebGLRenderer();
// renderer.setClearColor(0x000000, 1.0);
renderer.setClearColor( 0xffffff, 1 );
renderer.setSize(window.innerWidth, window.innerHeight);
// position and point the camera to the center of the scene
camera.position.x = 0;
camera.position.y = 40;
camera.position.z = 40;
camera.lookAt(scene.position);
// add the output of the renderer to the html element
document.body.appendChild(renderer.domElement);
// //init for sphere
// sphereCamera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 1, 1000);
// sphereCamera.position.y = -400;
// sphereCamera.position.z = 400;
// sphereCamera.rotation.x = .70;
sphere = new THREE.Mesh(new THREE.SphereGeometry(0.8,31,31), new THREE.MeshLambertMaterial({
color: 'yellow',
}));
light = new THREE.DirectionalLight('white', 1);
// light.position.set(0,-400,400).normalize();
light.position.set(0,10,10).normalize();
//get points covered by Spline
getSplineData();
}
//save points in geometry.vertices
function getSplineData() {
var curve = new THREE.CubicBezierCurve3(
new THREE.Vector3( -5, 0, 10 ),
new THREE.Vector3(0, 20, 0 ),
new THREE.Vector3(0, 20, 0 ),
new THREE.Vector3( 2, 0, -25 )
);
splineGeometry = new THREE.Geometry();
splineGeometry.vertices = curve.getPoints( 50 );
animate();
}
//scheduler loop
function animate() {
if(count == 50)
{
cancelAnimationFrame(animationTracker);
return;
}
//add line to the scene
drawLine();
renderer.render(scene, camera);
// renderer.render(scene, sphereCamera);
count += 1;
// camera.position.z -= 0.25;
// camera.position.y -= 0.25;
animationTracker = requestAnimationFrame(animate);
}
function drawLine() {
var lineGeometry = new THREE.Geometry();
var lineMaterial = new THREE.LineBasicMaterial({
color: 0x0000ff
});
console.log(splineGeometry.vertices[count]);
console.log(splineGeometry.vertices[count+1]);
lineGeometry.vertices.push(
splineGeometry.vertices[count],
splineGeometry.vertices[count+1]
);
var line = new THREE.Line( lineGeometry, lineMaterial );
scene.add( line );
}
// calls the init function when the window is done loading.
window.onload = init;
</script>
<body>
</body>
</html>
Drawback : The drawback of doing it the above way is that, end of the day, I'm drawing a line between consecutive points, and so I lose out on a lot of the effects possible in TubeGeometry such as, thickness, transparency etc.
Please suggest me an alternative way to get a smooth incremental load for the TubeGeometry.

THREE.TubeGeometry returns a THREE.BufferGeometry.
With THREE.BufferGeometry, you have access to a property drawRange that you can set to animate the drawing of the mesh:
let nEnd = 0, nMax, nStep = 90; // 30 faces * 3 vertices/face
...
const geometry = new THREE.TubeGeometry( path, pathSegments, tubeRadius, radiusSegments, closed );
nMax = geometry.attributes.position.count;
...
function animate() {
requestAnimationFrame( animate );
nEnd = ( nEnd + nStep ) % nMax;
mesh.geometry.setDrawRange( 0, nEnd );
renderer.render( scene, camera );
}
EDIT: For another approach, see this SO answer.
three.js r.144

Normally you would be able to use the method .getPointAt() to "get a vector for point at relative position in curve according to arc length" to get a point at a certain percentage of the length of the curve.
So normally if you want to draw 70% of the curve and a full curve is drawn in 100 segments. Then you could do:
var percentage = 70;
var curvePath = new THREE.CurvePath();
var end, start = curveQuad.getPointAt( 0 );
for(var i = 1; i < percentage; i++){
end = curveQuad.getPointAt( percentage / 100 );
lineCurve = new THREE.LineCurve( start, end );
curvePath.add( lineCurve );
start = end;
}
But I think this is not working for your curveQuad since the getPointAt method is not implemented for this type. A work around is to get a 100 points for your curve in an array like this:
points = curve.getPoints(100);
And then you can do almost the same:
var percentage = 70;
var curvePath = new THREE.CurvePath();
var end, start = points[ 0 ];
for(var i = 1; i < percentage; i++){
end = points[ percentage ]
lineCurve = new THREE.LineCurve( start, end );
curvePath.add( lineCurve );
start = end;
}
now your curvePath holds the line segments you want to use for drawing the tube:
// draw the geometry
var radius = 5, radiusSegments = 8, closed = false;
var geometry = new THREE.TubeGeometry(curvePath, percentage, radius, radiusSegments, closed);
Here a fiddle with a demonstration on how to use this dynamically

I'm not really that familiar with three.js. But I think I can be of assistance. I have two solutions for you. Both based on the same principle: build a new TubeGeometry or rebuild the current one, around a new curve.
Solution 1 (Simple):
var CurveSection = THREE.Curve.create(function(base, from, to) {
this.base = base;
this.from = from;
this.to = to;
}, function(t) {
return this.base.getPoint((1 - t) * this.from + t * this.to);
});
You define a new type of curve which just selects a segment out of a given curve. Usage:
var curve = new CurveSection(yourCurve, 0, .76); // Where .76 is your percentage
Now you can build a new tube.
Solution 2 (Mathematics!):
You are using for your arc a quadratic bezier curve, that's awesome! This curve is a parabola. You want just a segment of that parabola and that is again a parabola, just with other bounds.
What we need is a section of the bezier curve. Let's say the curve is defined by A (start), B (direction), C (end). If we want to change the start to a point D and the end to a point F we need the point E that is the direction of the curve in D and F. So the tangents to our parabola in D and F have to intersect in E. So the following code will give us the desired result:
// Calculates the instersection point of Line3 l1 and Line3 l2.
function intersection(l1, l2) {
var A = l1.start;
var P = l2.closestPointToPoint(A);
var Q = l1.closestPointToPoint(P);
var l = P.distanceToSquared(A) / Q.distanceTo(A);
var d = (new THREE.Vector3()).subVectors(Q, A);
return d.multiplyScalar(l / d.length()).add(A);
}
// Calculate the tangentVector of the bezier-curve
function tangentQuadraticBezier(bezier, t) {
var s = bezier.v0,
m = bezier.v1,
e = bezier.v2;
return new THREE.Vector3(
THREE.CurveUtils.tangentQuadraticBezier(t, s.x, m.x, e.x),
THREE.CurveUtils.tangentQuadraticBezier(t, s.y, m.y, e.y),
THREE.CurveUtils.tangentQuadraticBezier(t, s.z, m.z, e.z)
);
}
// Returns a new QuadraticBezierCurve3 with the new bounds.
function sectionInQuadraticBezier(bezier, from, to) {
var s = bezier.v0,
m = bezier.v1,
e = bezier.v2;
var ns = bezier.getPoint(from),
ne = bezier.getPoint(to);
var nm = intersection(
new THREE.Line3(ns, tangentQuadraticBezier(bezier, from).add(ns)),
new THREE.Line3(ne, tangentQuadraticBezier(bezier, to).add(ne))
);
return new THREE.QuadraticBezierCurve3(ns, nm, ne);
}
This is a very mathematical way, but if you should need the special properties of a Bezier curve, this is the way to go.
Note: The first solution is the simplest. I am not familiar with Three.js so I wouldn't know what the most efficient way to implement the animation is. Three.js doesn't seem to use the special properties of a bezier curve so maybe solution 2 isn't that useful.
I hope you have gotten something useful out of this.

spline not match ExtrudeGeometry in Three.js

I create a closed spline and extrude geometry with rectangle shape to create a track for my game. I use spline to calculate the position of my ship, but when I check, the spline does not match completely with the geometry. Is there something wrong?
shape used to extrude example
extrude geometry and spline not match
Here is my code:
var genTrack = function (lanes, controlPoints, material, isClose) {
//extrude setting
var extrudeSettings = {
bevelEnabled: true,
bevelSegments: 2,
steps: 200,
material: 1,
extrudeMaterial: 1
};
//track shape
var trackShape = new THREE.Shape([
new THREE.Vector2(-config.laneHeight/2, config.laneWidth/2),
new THREE.Vector2(-config.laneHeight/2, - config.laneWidth/2),
new THREE.Vector2(config.laneHeight/2, - config.laneWidth/2),
new THREE.Vector2(config.laneHeight/2, config.laneWidth/2),
]);
//spline
if (isClose)
var spline = new THREE.ClosedSplineCurve3(controlPoints);
else
var spline = new THREE.SplineCurve3(controlPoints);
utils.public('spline', spline);
//set path
extrudeSettings.extrudePath = spline;
//frenet
var frenet = new THREE.TubeGeometry.FrenetFrames(spline, 200, false)
extrudeSettings.frames = frenet;
utils.public('extrudeSettings', extrudeSettings);
//create geometry
var geometry = new THREE.ExtrudeGeometry(trackShape, extrudeSettings);
var splineGeo = new THREE.TubeGeometry(spline, 200, 1, 4, true, false);
utils.public('frenet', frenet);
var angle = 0;
var track = new THREE.Object3D();
track.matrixAutoUpdate = false;
track.receiveShadow = true;
for (var i=0; i< lanes; i++){
var mesh = new THREE.Mesh(geometry, material);
mesh.position.set(i * (config.laneSpan + config.laneWidth), -30, 0);
//mesh.rotation.set(0, 0,angle);
//angle += Math.PI/180 * 20;
track.add(mesh);
}
track.scale.set(1.5, 1.5, 1.5);
var splineMesh = new THREE.Mesh(splineGeo, new THREE.MeshBasicMaterial({color: 0xffffff}));
return {
'geometry': geometry,
'mesh': track,
'spline': spline,
'frenet': frenet,
'splineMesh': splineMesh,
'controlPoints' : controlPoints
};
}

I believe your problem is with this line:
mesh.position.set(i * (config.laneSpan + config.laneWidth), -30, 0);
I think what you want is something more like:
mesh.position.set(i * config.laneWidth / lanes, config.laneHeight / 2, 0);
I haven't tested it, but I think you need something like this.