I've been using the THREE.Raycaster successfully to test collisions for many things in my game engine so far, it's great and it works well.
However, recently I've run into something quite peculiar which I cannot seem to figure out. From my point of view, my logic and code are sound but the expected result is not correct.
Perhaps I'm just missing something obvious so I thought I'd ask for some help.
I am casting rays out from the center of the top of a group of meshes, one by one, in a circular arc. The meshes are all children of a parent Object3D and the goal is to test collisions between the origin mesh and other meshes which are also children of the parent. To test my rays, I am using the THREE.ArrowHelper.
Here's an image of the result of my code - http://imgur.com/ipzYUsa
In this image, the ArrowHelper objects are positioned (origin:direction) exactly how I want them. But yeah, there's something wrong with this picture, the code that is produces this is:
var degree = Math.PI / 16,
tiles = this.tilesContainer.children,
tilesNum = tiles.length,
raycaster = new THREE.Raycaster(),
rayDirections, rayDirectionsNum, rayOrigin, rayDirection, collisions,
tile, i, j, k;
for (i = 0; i < tilesNum; i++) {
tile = tiles[i];
rayOrigin = new THREE.Vector3(
tile.position.x,
tile.geometry.boundingBox.max.y,
tile.position.z
);
rayDirections = [];
for (j = 0; j < Math.PI * 2; j += degree) {
rayDirections.push(new THREE.Vector3(Math.sin(j), 0, Math.cos(j)).normalize());
}
rayDirectionsNum = rayDirections.length;
for (k = 0; k < rayDirectionsNum; k++) {
rayDirection = rayDirections[k];
raycaster.set(rayOrigin, rayDirection);
collisions = raycaster.intersectObjects(tiles);
this.testRay(rayOrigin, rayDirection, collisions);
}
}
The testRay method looks like this:
testRay: function (origin, direction, collisions) {
var arrowHelper = new THREE.ArrowHelper(
direction,
origin,
1,
(collisions.length === 0) ? 0xFF0000 : 0x0000FF
);
this.scene.add(arrowHelper);
}
Now, obviously, something is off about this image. The rays that collide with other meshes should be blue, while those that do not collide should be red.
It's clear from this image that something is totally out of whack, and when I inspect the collisions, I get some really off results. For a lot of those rays which appear blue in the image, I'm getting a huge number of collisions, something like 30 collisions for a single ray sometimes, but nothing for the others even when they are right next to other tiles.
I just can't figure out what it might be. How can it be that so many rays that should be blue are red? And how can rays from tiles at the edge of the level have blue collisions to tiles that do not exist?
Really scratching my head (read: bashing my head repeatedly) over this one, any help would be super appreciated!
The solution was actually outside this code and not, at least I don't believe, related to the outdated r68 build.
When making the tile meshes, I needed to set three properties on them
tileMesh.matrixAutoUpdate = false;
tileMesh.updateMatrix();
tileMesh.updateMatrixWorld(); // this is new
I was doing the first two, just not the last one. Why this is necessary, I do not know, it seems a little odd to me but this is what fixed my problem. I had an AxisHelper in the scene, if you look at the original image, you'll notice that all the ArrowHelper objects that are blue are actually pointing towards the AxisHelper. This is really weird because the AxisHelper was added to the scene, not to tilesContainer. Adding the ArrowHelper objects to tilesContainer did not help.
The process to render the scene had the raycaster code run before the AxisHelper was added to the scene and before the initial render happened. The problem was also fixed if I moved the raycaster code call after the AxisHelper was added, but this was a hacky solution.
So the true fix was to add .updateMatrixWorld() to the tiles. The result now looks like this http://imgur.com/8LewqxL, which is correct (the ArrowHelper objects have been shortened in length so they don't overlap).
Big thanks to Manthrax for his help on this one.
I think you make some local vs global space error. I don't see so fast where exactly you go wrong, but all your position and direction calculations seem to be in the local system of the tilesContainer. Are you consistent in your local vs global coordinate system handling?
For example you add your arrowHelper to the scene instead of to the tilesContainer. It could be that the tilesContainer has some rotation set and because of this the arrows are pointing in another direction then you expected.
What happens for example if you add the arrows to the tilesContainer instead?
Related
In this code pen,
you'll find a parametric flower that is using a red THREE.MeshBasicMaterial with a wireframe, it looks like this:
with wireframe: false, it looks like this:
Basically, I just want it to be a solid geometry
I tried to set the indices of the buffer geometry manually, but actually setting the indices as defined by this code:
let faces = []
for ( var i=0; i<positions.length; i+=3) {
faces.push( i, i+3, i+2 )
faces.push( i, i+1, i+3 )
}
var indices = new Uint16Array( faces );
geometry.setIndex( new THREE.BufferAttribute( indices, 1 ) );
does nothing, and returns a black screen. So, the default view of the buffergeometry with the indices defined by the position buffer is what appears in the codepen.
Essentially, the problem I'm having is that I can't figure out the proper index to use, and why using any index just returns a black screen.
I looked at other examples from stackoverflow, like
how to understand setindex and index in buffer geometry
and
threejs correct way to setindex indices for buffergeometry
but they basically just described what I'm doing now, which is unhelpful.
The original code for this comes from another stackoverflow article, which is linked to, here, it defines the rose as a parametric equation, but it's based on a THREE.PointsMaterial, and does not work as a solid geometry. So I tried to make it work myself, and this is the result I got and if anyone knows how to fix it please let me know.
I did also decide to make a version of this using a THREE.ParametricGeometry but that method is extremely inefficient for what I want to accomplish, so my road has led me here, generating the points manually and adding them to a buffergeometry is SO much more efficient than using a THREE.ParametricGeometry. If you can help figure out how to properly set the index of the points to appear properly as faces, I would be so grateful because it would solve the problem I'm having of setting the index, so that the flower would appear as a solid geometry.
I figured it out!
https://codepen.io/ricky1280/pen/mdjOYba?editors=1010
the 2D loop should look like this:
for(let r=0; r < v.length; r++){
// fill(340,100, -20+r*r_D*120)
for(let theta =0; theta < v[r].length; theta++){
if(r < v.length-1 && theta< v[r].length-1){
positions.push(v[r][theta].x*1, v[r][theta].y*1, v[r][theta].z*1);
positions.push(v[r+1][theta].x*1, v[r+1][theta].y*1, v[r+1][theta].z*1);
positions.push(v[r+1][theta+1].x*1,v[r+1][theta+1].y*1,v[r+1][theta+1].z*1);
positions.push(v[r][theta].x*1, v[r][theta].y*1, v[r][theta].z*1);
positions.push(v[r][theta+1].x*1,v[r][theta+1].y*1,v[r][theta+1].z*1);
positions.push(v[r+1][theta+1].x*1,v[r+1][theta+1].y*1,v[r+1][theta+1].z*1);
}
}
}
Generally, instead of adding the positions to the array and then setting an index, add them to the array as if they were being used with respect to an index.
With this answer in mind the vertices of the p5js geometry should be modified along the same lines.
I have a total of 1 to 64 blobs and they all move to my mouse position. But i want them to not go into each other, in other words circle collision detection. However i can't seem to make it smooth and also push new objects after they move for the first time?
Tried checking each blob for collision with other blobs. If collosion is true, then set the distance between the blobs to their accumulated radiuses.
This is how i wrote the colliding function, but this way of doing it makes the resetting of positions too fast. I want it to be a smooth, but fast transition. Like instead of now 1 frame, lets say 10 frames. And another problem is when two objects' are distanced to their radiuses, they might collide into new ones and that will cause this code to run again, and then all blobs go crazy.
this.collide = function() {
var length = this.blobs.length; // How many blobs?
this.blobs.forEach(function(item, index) {
for (var i = 0; i < length; i++) {
// Get absolute distance between two vectors
var v0 = vectorFromTo(blob.blobs[i].pos.x, blob.blobs[i].pos.y, //[x2, y2]
item.pos.x, item.pos.y); //[x1, y1]
// if colliding, set distance between to their accumulated radiuses
if (magnitude(v0) < blob.blobs[i].r + item.r) {
item.pos.add(v0.setMag(magnitude(v0) - (blob.blobs[i].r + item.r)));
}
}
});
}
I haven't tried to code another way of doing this yet because i haven't learned about vectors in school, but i do understand them quite a bit. But what i think would work is if i checked for collision, and if they collide they go opposite directions 50% of the deficit distance, and then they check if they hit new blobs. But this would require physics right? Cause then it would have to do something with the mass and speed of the blob as well to know whats gonna happen to the new blob it crashes into?
EDIT:
This is what im looking for: https://youtu.be/QvlhRGtlcsw
This is what it currently looks like: https://youtu.be/QEpHnCgomqY
in my project I have a player walk around a globe. The globe is not just a sphere, it has mountains and valleys, so I need the players z position to change. For this I'm raycasting a single ray from player's position against a single object (the globe) and I get the point they intersect and change players position accordingly. I'm only raycasting when the player moves, not on every frame.
For a complex object it takes forever. It takes ~200ms for an object with ~1m polys (faces) (1024x512 segments sphere). Does raycasting cast against every single face ?
Is there a traditional fast way to achieve this in THREE, like some acceleration structure (octree? bvh? -- tbh from my google searches I haven't seem to find such a thing included in THREE) or some other thinking-out-of-the-box (no ray casting) method?
var dir = g_Game.earthPosition.clone();
var startPoint = g_Game.cubePlayer.position.clone();
var directionVector = dir.sub(startPoint.multiplyScalar(10));
g_Game.raycaster.set(startPoint, directionVector.clone().normalize());
var t1 = new Date().getTime();
var rayIntersects = g_Game.raycaster.intersectObject(g_Game.earth, true);
if (rayIntersects[0]) {
var dist = rayIntersects[0].point.distanceTo(g_Game.earthPosition);
dist = Math.round(dist * 100 + Number.EPSILON) / 100;
g_Player.DistanceFromCenter = dist + 5;
}
var t2 = new Date().getTime();
console.log(t2-t1);
Thank you in advance
Do not use three.js Raycaster.
Consider Ray.js that offers function intersectTriangle(a, b, c, backfaceCulling, target)
Suggested optimizations:
If player starts from some known positions ⇒ you must know his initial height, − no need to raycast (or just do one time full mesh slow intersection)
if player moves with small steps ⇒ next raycast will most likely intersect the same face as before.
Optimization #1 − remember previous face, and raycast it first.
if player does not jump ⇒ next raycast will most likely intersect the adjacent face to the face where player was before.
Optimization #2 − build up a cache, so that given a face idx you could retrieve adjacent faces in O(1) time.
This cache may be loaded from the file, if your planet is not generated in real time.
So with my approach on each move you do O(1) read operation from cache and raycast 1-6 faces.
Win!
For a complex object it takes forever. It takes ~200ms for an object with ~1m polys (faces) (1024x512 segments sphere). Does raycasting cast against every single face ?
Out of the box THREE.js does check every triangle when performing a raycast against a mesh and there are no acceleration structures built into THREE.
I've worked with others on the three-mesh-bvh package (github, npm) to help address this problem, though, which may help you get up to the speeds your looking for. Here's how you might use it:
import * as THREE from 'three';
import { MeshBVH, acceleratedRaycast } from 'three-mesh-bvh';
THREE.Mesh.prototype.raycast = acceleratedRaycast;
// ... initialize the scene...
globeMesh.geometry.boundsTree = new MeshBVH(globeMesh.geometry);
// ... initialize raycaster...
// Optional. Improves the performance of the raycast
// if you only need the first collision
raycaster.firstHitOnly = true;
const intersects = raycaster.intersectObject(globeMesh, true);
// do something with the intersections
There are some caveats mentioned in the README so keep those in mind (the mesh index is modified, only nonanimated BufferGeometry is supported, etc). And there's still some memory optimization that could be done but there are some tweakable options to help tune that.
I'll be interested to hear how this works for you! Feel free to leave feedback in the issues on how to improve the package, as well. Hope that helps!
I think you should pre-render the height map of your globe into a texture, assuming your terrain is not dynamic. Read all of it into a typed array, and then whenever your player moves, you only need to back-project her coordinates into that texture, query it, offset and multiply and you should get what you need in O(1) time.
It's up to you how you generate that height map. Actually if you have a bumpy globe, then you should probably start with height map in the first place, and use that in your vertex shader to render the globe (with the input sphere being perfectly smooth). Then you can use the same height map to query the player's Z.
Edit: Danger! This may cause someone's death one day. The edge case I see here is the nearest collision will be not be seen because searchRange will not contain the nearest triangle but will contain the second nearest one returning it as the closest one. I.e. a robotic arm may stop nearby the torso instead of stopping at the arm right in front of it.
anyway
Here's a hack when raycasting not too far from the previous result i.e. during consecutive mousemove events. This will not work for completely random rays
Mesh raycast supports drawRange to limit how many triangles will be searched. Also each raycast result comes with faceIndex telling which triangle was hit. If you're continuously looking for raycasts i.e. with mousemove or there's a laser linearly scanning a mesh you can first search the area nearby* the previous hit.
triangles' distance in the data may look like they're neighbours but it's not guaranteed they are sorted in any way. Still it's very possible that the close ones in the data are close in space.
let lastFaceIndex = null
const searchRange = 2000 * 3
function raycast(mesh, raycaster) {
// limited search
if (lastFaceIndex !== null) {
const drawRange = mesh.geometry.drawRange
drawRange.start = Math.max(0, lastFaceIndex * 3 - searchRange)
drawRange.count = searchRange * 2
const intersects = raycaster.intersectObjects([mesh]);
drawRange.start = 0
drawRange.count = Infinity
if (intersects.length) {
lastFaceIndex = intersects[0].faceIndex
return intersects[0]
}
}
// regular search
const intersects = raycaster.intersectObjects([mesh]);
if (!intersects.length) {
lastFaceIndex = null
return null
}
lastFaceIndex = intersects[0].faceIndex
return intersects[0]
}
I have a scene with lots of objects using ExtrudeGeometry. Each of these need to update each frame, where the shape that is being extruded is changing, along with the amount of extrusion. The shapes are being generated using d3's voronoi algorithm.
See example.
Right now I am achieving this by removing every object from the scene and redrawing them each frame. This is very costly and causing performance issues. Is there a way to edit each mesh/geometry instead of removing from the scene? Would this help with performance? Or is there a more efficient way of redrawing the scene?
I'd need to edit both the shape of the extrusion and the amount of extrusion.
Thanks for taking a look!
If you're not changing the number of faces, you can use morph targets http://threejs.org/examples/webgl_morphtargets.html
You should
Create your geometry
Clone the geometry and make your modifications to it, such as the maximum length of your geometry pillar
Set both geometries as morph targets to your base geometry, for example
baseGeo.morphTargets.push(
{ name: "targetName", vertices: [ modifiedVertexArray ] }
);
After that, you can animate the mesh this using mesh.updateMorphTargets()
See http://threejs.org/examples/webgl_morphtargets.html
So I managed to come up with a way of not having to redraw the scene every time and it massively improved performance.
http://jsfiddle.net/x00xsdrt/4/
This is how I did it:
Created a "template geometry" with ExtrudeGeometry using a dummy
10 sided polygon.
As before, created a bunch of "points", this time assigning each
point one of these template geometries.
On each frame, iterated through each geometry, updating each vertex
to that of the new one (using the voronoi alg as before).
If there are extra vertices left over, "bunch" them up into a single point. (see http://github.com/mrdoob/three.js/wiki/Updates.)
Looking at it now, it's quite a simple process. Before, the thought of manipulating each vertex seemed otherworldly to me, but it's not actually too tricky with simple shapes!
Here's how I did the iteration, polycColumn is just a 2 item array with the same polygon in each item:
// Set the vertex index
var v = 0;
// Iterate over both top and bottom of poly
for (var p=0;p<polyColumn.length;p++) {
// Iterate over half the vertices
for (var j=0;j<verts.length/2;j++) {
// create correct z-index depending on top/bottom
if (p == 1) {
var z = point.extrudeAmount;
} else {
var z = 0;
}
// If there are still legitimate verts
if (j < poly.length) {
verts[v].x = poly[j][0];
verts[v].y = poly[j][1];
verts[v].z = z;
// If we've got extra verts, bunch them up in the same place
} else {
verts[v].x = verts[v - 1].x;
verts[v].y = verts[v - 1].y;
verts[v].z = z;
}
v++;
}
}
point.mesh.geometry.verticesNeedUpdate = true;
I am creating a program which populate a world with blocks on the ground upon mouse click (the coordinate is based on the mouse click coordinate, which I've calculated). When creating a new block, it should not intersects with the ones already made beforehand. I achieved this checking with THREE.Raycaster. Basically I cast rays from the block's center in all direction of its vertices.
var ln = preview.geometry.vertices.length;
//for each vertices we throw a ray
for(var i = 0; i < ln; i++){
var pr_vertex = preview.geometry.vertices[i].clone();
var gl_vertex = pr_vertex.applyMatrix4(preview.matrix);
var dr_vector = gl_vertex.sub(preview.position);
var ray = new THREE.Raycaster(preview.position, dr_vector.clone().normalize());
var intersects = ray.intersectObjects(objmanager.getAllObject(), true);
//if there is intersection
if(intersects.length > 0 && intersects[0].distance < dr_vector.length()){
//hide preview material
preview.material.opacity = 0;
//exit checking
break;
}
}
preview is the name of the object. This code already worked perfectly. The problem is, Raycaster.intersectObjects only worked when the ray intersects with the front face of the tested object. I've tested it when I ran the code, if the ray start from outside the tested object, they intersected just fine. But when the ray started if from the inside of the tested block, it didn't catch the intersection with the tested block's surface. I presume that this happens because intersectObjects only worked with the tested object's front surface. Is this true?
Intuitively, I tried to solve this problem using THREE.DoubleSide (making a double-sided objects). But it produced an error because the shader failed to initialize.
Could not initialise shader
VALIDATE_STATUS: false, gl error [0] three.js:25254
buildProgram three.js:25254
initMaterial three.js:23760
setProgram three.js:23830
renderBuffer three.js:22371
renderObjects three.js:23061
render three.js:22935
animLoop
I'm using THREE.MeshLambertMaterial. When I used MeshBasicMaterial, the Raycaster.intersectObjects just didn't work at all.
So I hit a roadblock now. Is there any idea to solve this problem? Either that, or I would have to test the collision manually with each objects' individual faces (which I'm afraid would hit the performance hard).
Thank you in advance.
===============
edit: I forgot to mention, I'm using the newest three.js version, which should be around r63
If you set:
object.material.side = THREE.DoubleSided
you should get hits on both surfaces.
If double sided you'll have two intersections :
object.material.side = THREE.DoubleSide