CODEWITHSUNDEEP
javascriptthree.js
user3491125
user3491125

Reputation: 366

How to Raycast from an Arbitrary Point

so here's my problem, as i was using three js on a project where user gives x y coordinates a point is added on a three js scene and i need to calculate the position of the collide object behind/in front of this point. I tried using Raycaster but I couldn't find a simple example of how to use Raycaster with a vector defined by point :/ here's my code so far 

var projector = new THREE.Projector();
    var directionVector = new THREE.Vector3();
     /* how could i use a vector defined by my origin point

     var origin = new THREE.Vector3(x, y, 0 );

     instead of the camera vector as used below ? 
     */
     projector.unprojectVector(directionVector, camera);
     directionVector.sub(camera.position);
     directionVector.normalize();
     var ray = new THREE.Raycaster();
     ray.set(camera.position,directionVector)
     var intersects = ray.intersectObjects(scene.children);
        if (intersects.length > 0) {
            console.log(intersects);
        }

Upvotes: 1

Views: 261

Answers (1)

WestLangley
WestLangley

Reputation: 104843

To raycast from an arbitrary point, you can use this pattern:

var raycaster = new THREE.Raycaster(); // create once, and reuse
var origin = new THREE.Vector3(); // reuse it
var direction = new THREE.Vector3(); // reuse it
...

origin.set( x, y, z );
direction.set( 0, 0, - 1 ).normalize(); // direction vector must have unit length
raycaster.set( origin, direction );
var intersects = raycaster.intersectObjects( objects, recursiveFlag );
if ( intersects.length > 0 ) {      
    // your code        
}

three.js r.75

Upvotes: 3

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