I'm fairly new to three.js and trying to get a better understanding of ray casting. I have used it so far in a game to show when an object collides with another on the page which works perfectly. In the game I'm building this is to take health from the hero as it crashes into walls.
I am now trying to implement a target which when hovered over some objects it will auto shoot. However the target only registers a target hit once the object passes through the target mesh rather than when its ray is cast through it.
to further detail this, the ray is cast from the camera through the target, if the target is on a mesh (stored as an object array) then I want it to trigger a function.
within my update function I have this:
var ray = new THREE.Raycaster();
var crossHairClone = crossHair.position.clone();
var coards = {};
coards.x = crossHairClone.x
coards.y = crossHairClone.y
ray.setFromCamera(coards, camera);
var collisionResults = ray.intersectObjects( collidableMeshList );
if ( collisionResults.length > 0 ) {
console.log('Target Hit!', collisionResults)
}
The console log is only triggered when the collidableMeshList actually touches the target mesh rather than when it is aiming at it.
How do I extend the ray to pass through the target (which I thought it was already doing) so that if anything hits the ray then it triggers my console log.
Edit
I've added a URL to the game in progress. There are other wider issues with the game, my current focus is just the target ray casting.
Game Link
Many thanks to everyone who helped me along the way on this one but I finally solved it, only not through the means that I had expected to. Upon reading into the setFromCamera() function it looks like it is mainly used around mouse coards which in my instance was not what I wanted. I wanted a target on the page and the ray to pass through this. For some reason my Ray was shooting vertically up from the centre of the whole scene.
In the end I tried a different approach and set the Rays position and direction directly rather rely on setting it from the cameras position.
var vector = new THREE.Vector3(crossHair.position.x, crossHair.position.y, crossHair.position.z);
var targetRay = new THREE.Raycaster(camera.position, vector.sub(camera.position).normalize());
var enemyHit = targetRay.intersectObject( enemy );
if ( enemyHit.length > 0 ) {
console.log('Target Hit!', targetRay)
}
I'll leave this up for a while before accepting this answer in case anyone has a better approach than this or has any corrections over what I have said in regards to setFromCamera().
Related
I'm rather new to threejs, so what I'm doing might not be the most efficient way.
I have an object in AR on a mobile device and I want to know if I intersect with it when touching on the screen.
I use the following code to generate the raycast, and it works initally.
const tempMatrix = new THREE.Matrix4();
tempMatrix.identity().extractRotation(this.controller.matrixWorld);
this.raycaster.ray.origin.setFromMatrixPosition(this.controller.matrixWorld);
this.raycaster.ray.direction.set(0, 0, -1).applyMatrix4(tempMatrix);
However, I have the ability to reposition the object (i.e. reset the position so the object is in front, relative to the current camera direction and position) by moving and rotating the whole scene.
After the repositioning, the raycasting is completely offset and is not casting rays anywhere near where I touch the screen.
Repositioning is done like this (while it works, if there's a better way, let me know!) :
public handleReposition(): void {
const xRotation = Math.abs(this.camera.rotation.x) > Math.PI / 2 ? -Math.PI : 0;
const yRotation = this.camera.rotation.y;
this.scene.rotation.set(xRotation, yRotation, xRotation);
this.scene.position.set(this.camera.position.x, this.camera.position.y, this.camera.position.z);
}
How can I achieve to raycast to the correct new location?
Thanks!
Assuming this.scene is actually the main threejs Scene, it's usually a bad idea to change its rotation or position, since it will affect everything inside the scene, including the controller. I'd suggest moving your object instead, or add your object(s) to a Group and move that.
I am trying to make use of Raycaster in a ThreeJS scene to create a sort of VR interaction.
Everything works fine in normal mode, but not when I enable stereo effect.
I am using the following snippet of code.
// "camera" is a ThreeJS camera, "objectContainer" contains objects (Object3D) that I want to interact with
var raycaster = new THREE.Raycaster(),
origin = new THREE.Vector2();
origin.x = 0; origin.y = 0;
raycaster.setFromCamera(origin, camera);
var intersects = raycaster.intersectObjects(objectContainer.children, true);
if (intersects.length > 0 && intersects[0].object.visible === true) {
// trigger some function myFunc()
}
So basically when I try the above snippet of code in normal mode, myFunc gets triggered whenever I am looking at any of the concerned 3d objects.
However as soon as I switch to stereo mode, it stops working; i.e., myFunc never gets triggered.
I tried updating the value of origin.x to -0.5. I did that because in VR mode, the screen gets split into two halves. However that didn't work either.
What should I do to make the raycaster intersect the 3D objects in VR mode (when stereo effect is turned on)?
Could you please provide a jsfiddle with the code?
Basically, if you are using stereo in your app, it means you are using 2 cameras, therefore you need to check your intersects on both cameras views, this could become an expensive process.
var cameras =
{ 'camera1': new THREE.PerspectiveCamera(50, window.innerWidth / window.innerHeight, 1, 10000),
'camera2': new THREE.PerspectiveCamera(50, window.innerWidth / window.innerHeight, 1, 10000)
};
for (var cam in cameras) {
raycaster.setFromCamera(origin, cameras[cam]);
//continue your logic
}
You could use a vector object that simulates the camera intersection to avoid checking twice, but this depends on what you are trying to achieve.
I encountered a similar problem, I eventually found the reason. Actually in StereoEffect THREE.js displays the meshes on the two eyes, but in reality is actually adds only one mesh to the scene, exactly in the middle of the line left-eye-mesh <-> right-eye-mesh, hidden to the viewer.
So when you use the raycaster, you need to use it on the real mesh on the middle, not the illusion displayed on each eye !
I detailled here how to do it
Three.js StereoEffect displays meshes across 2 eyes
Hopes it solves your problem !
You can use my StereoEffect.js file in your project for resolving problem. See example of using. See my Raycaster stereo pull request also.
I have a Box Mesh where I subtract another Box with Three.CSG to create a wall with a window.
After doing so, there are tiny holes in the Mesh alongside the cut. They are not visible alle the time, but show up when moving around.
How to close these holes?
This is part of the code how I am creating the Mesh:
var wallBsp = new ThreeBSP( myWallMesh );
var subMesh = new THREE.Mesh( mygeo );
var subBsp = new ThreeBSP( subMesh );
var subtract_bsp = wall_bsp.subtract( subBsp );
var result = subtract_bsp.toMesh();
result.material.shading = THREE.FlatShading;
result.geometry.computeVertexNormals();
Update
I have created a jsfiddle, but it is difficult to reproduce the error, I couldnt make it visible there: http://jsfiddle.net/L0rdzbej/23/
However, you can see the full application here.
Like #gaitat suggested, geometry.mergeVertices() does not look like it changes anything for me. Chandler Prall hinted at the source where precisionPoints, which is a variable inside the mergeVertices function, could solve this. Depending on the scale of the scene its value should be lower or negative, but I had no success so far.
I think the problem might be because it's a loaded object and not a "created" geometry, but I want to be able to select an object and show that it is selected, like in this example.
I load multiple objects in and I keep track of an index for each object (so the first object loaded has objIndex = 0, etc.) and I know that my code recognizes when I "mouse down" from the console. However, it says that intersects.length = 0 so the rest of the function is skipped.
I'm also not sure what "intersects.length" is actually taking the length of.
So I suppose my questions are:
What is "intersects.length" taking the length of?
Why do my objects have an "intersects.length" of 0?
What are some things I could do so that the objects are recognized?
Here's the relevant code:
function onDocumentMouseDown(event) {
event.preventDefault();
// default action of event will not be triggered
var vector = new THREE.Vector3(mouse.x, mouse.y, 0.5).unproject(camera);
// used to pass 3D positions and directions
var raycaster = new THREE.Raycaster(camera.position,
vector.sub(camera.position).normalize());
var intersects = raycaster.intersectObjects(objects);
console.log('Mouse is down.');
console.log(intersects.length);
if (intersects.length > 0) {
controls.enabled = false;
SELECTED = intersects[0].object;
var intersects = raycaster.intersectObjects(plane);
offset.copy(intersects[0].point).sub(plane.position);
container.style.cursor = 'move';
console.log('Clicked object: ' + object.name);
}
}
If you need to see more, let me know! Thank you. :)
Answering your question:
Here is an interesting read on raycast to help clarify raycasting:
http://soledadpenades.com/articles/three-js-tutorials/object-picking/
So what raycasting basically do is to (really) cast an imaginary ray. When you "mouse down" your program will, so called, cast a straight-line array into the scene. Now to answer your question:
For question one(1) and two(2) : Now when you cast a ray, it may or may not intersect an object. For example if you click into an empty space, the ray will not catch an object. However, as the name suggest, a raycast cast a ray and it may also hits multiple objects along the way. For example if you have one object and another object positioned directly behind the first object, casting a ray into the first object will also intersects the second object. The ray cast will "catch" both objects and put in the two objects into into the array "intersects". Therefore, the command
if (intersects.length > 0)
stated that if the raycast "catches" and object, do these. Moreover, it keeps on calling intersects[0] to refer to the first objects in the intersects array. In this case the most front object that the raycast catches. You can test my answer by creating hundreds of objects and state that, for every member in the intersects array, you change the color to red(for example). You will see that if the raycast catches multiple objects, all the objects will turn into that color. Hope for the first two question!
I am not sure of what you are asking for the third question. Can you clarify further? One way for the object to be recognized is to put them into the scene and put a raycast on the scene. However, I am not too sure of what you are asking to give you answer that I think you want.
I've just started learning THREE and have been messing about with the three.js example of controllable MD2 characters to try and fashion it into a 3rd person shooter kind of game. I've been trying to write a simple algorithm for the enemy characters and I'm pretty sure that ray-casting would be ideal.The whole idea is that the enemies should stop rotating once they're facing the player. But Here's the problem that's giving me sleepless nights! :
Let's say, the enemy object is the origin for the ray caster ray. No matter what direction I set for the direction of that ray ( even, for example (1,0,0) - the positive x-axis), the ray's direction is always pointing towards the center of the scene!!!
Please help! haven't been able to find any Example online for this kind of use for the ray caster (apart from collision detection which I really don't need at the moment).
If all you want is for enemies to stop rotating when they are looking at the player, I would consider just checking the direction between them, as it's a lot faster than casting a ray to see if it intersects:
// Assuming `enemy` is a THREE.Mesh
var targetDir = enemy.position.clone().sub(player.position).normalize();
var currentDir = (new THREE.Vector3()).applyMatrix4(enemy.matrixWorld).sub(enemy.position).normalize();
var amountToRotate = currentDir.sub(targetDir);
var offset = amountToRotate.length();
Then rotate each axis no more than the value for that axis in amountToRotate if offset is greater than some threshold.
That said, here is how you use a Raycaster, given the variables above:
var raycaster = new THREE.Raycaster(enemy.position, targetDir);
var intersections = raycaster.intersectObject(player);
Note that if you are running any of the above code in an animation loop, it will create a lot of garbage collection churn because you are constantly creating a bunch of new objects and then immediately throwing them away. A better pattern, which is used a lot in the library itself, is to initialize objects once, copy values to them if you need to, and then use those copies for computation. For example, you could create a function to do your raycasting for you like this:
var isEnemyLookingAtPlayer = (function() {
var raycaster = new THREE.Raycaster();
var pos = new THREE.Vector3();
return function(enemy) {
raycaster.ray.origin.copy(enemy.position);
raycaster.ray.direction.copy(pos.copy(enemy.position).sub(player.position).normalize());
return !!raycaster.intersectObject(player).length;
};
})();