CODEWITHSUNDEEP
three.js
tripdragon
tripdragon

Reputation: 191

Threejs, What is the proper way to normalize a vector for correct direction on arrow helper

This is most likely a math issue. I have a line geometry that feeds its vertices positions to an arrow helper. The arrow helper runs normalize() on its direction vector to render its output. If I lay them over each other in the view the arrow vector shoots upward while the line is perfectly drawing to the right of the screen. I am expecting the arrow helper to be in sync with the line geometry.

var origin = new THREE.Vector3(0, 10, 0);
var direction = new THREE.Vector3(80, 10, 0);
direction.normalize();
/*
    direction after its normalized
    Object
    x: 0.9922778767136676
    y: 0.12403473458920845
    z: 0
*/

http://jsbin.com/nazapabaxaco/1/edit?html,js,output

Mathematically this is actually correct for the arrow helper vector. But its not the expected result. If I increase the distance X to say 500 the two converge again but not completely, they are still out of sync and just shooting apart at a really long distance.

The vector in use would be coming from a moving object and not the camera's unproject method so the points need to remain dynamically fed into.

Upvotes: 2

Views: 6006

Answers (1)

WestLangley
WestLangley

Reputation: 104843

You compute the direction vector by subtracting one line segment endpoint from the other, and then normalizing.

Upvotes: 4

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