While going through the tutorial on drawing lines in three.js documentation, I came across this code snippet:
The code seems to be perfectly fine without any issues.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>My first three.js app</title>
<style>
body { margin: 0; }
</style>
</head>
<body>
<script src="///C:/Users/pc/Desktop/threejs_tutorial/build_threejs.html"></script>
<script>
const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 1, 500 );
camera.position.set( 0, 0, 100 );
camera.lookAt( 0, 0, 0 );
const renderer = new THREE.WebGLRenderer();
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );
//create a blue LineBasicMaterial
const material = new THREE.LineBasicMaterial( { color: 0x0000ff } );
const points = [];
points.push( new THREE.Vector3( - 10, 0, 0 ) );
points.push( new THREE.Vector3( 0, 10, 0 ) );
points.push( new THREE.Vector3( 10, 0, 0 ) );
const geometry = new THREE.BufferGeometry().setFromPoints( points );
const line = new THREE.Line( geometry, material );
scene.add( line );
renderer.render( scene, camera );
</script>
</body>
</html>
One interesting part of the code for me was the camera.position.set and camera.lookAt commands.
camera.position.set( 0, 0, 100 );
camera.lookAt( 0, 0, 0 );
I believe that the three numbers correspond to the x, y, and z axes of the 3D space. While I have some understanding of these parts of the code, I find it fascinating to relate them to the concept of frustrum as the camera and its field of view...:-)
The code camera.position.set( 0, 0, 100 ) implies that the camera is positioned 100 units along the Z-axis from the origin.
The code camera.lookAt( 0, 0, 0 ) indicates that the orientation of the camera is towards the origin.
Combining these two concepts, we can visualize the code as follows:
https://i.sstatic.net/WiLfJ.jpg
How do you interpret the camera.position.set and camera.lookAt commands in three.js? Does your visualization match what I imagined?