Determine if a mesh is visible on the viewport according to current camera

Question

I have been developing an app with three.js but I have encountered this problem and I cannot seem to find any solution to it. I want to determine which meshes are visible right now according to where the camera is currently aiming, so i can refresh my objects (data is coming from a service) or not depending on if they are being shown on the viewport.

I'm using THREE.js in CANVAS mode (I have found a solution using WebGL that says if objects are rendered or not, but i need CANVAS for this project).

I have been trying to find if three.js sets somehow a property to indicate whether the object is visible or not (currently on the screen, not on the entire 3D world), but I can't find it. Meshes have a visible: property but it's always on true even if the camera is not aiming to that object.

Answer 1

This is the code you're after:

var frustum = new THREE.Frustum();
var cameraViewProjectionMatrix = new THREE.Matrix4();

// every time the camera or objects change position (or every frame)

camera.updateMatrixWorld(); // make sure the camera matrix is updated
camera.matrixWorldInverse.getInverse( camera.matrixWorld );
cameraViewProjectionMatrix.multiplyMatrices( camera.projectionMatrix, camera.matrixWorldInverse );
frustum.setFromMatrix( cameraViewProjectionMatrix );

// frustum is now ready to check all the objects you need

console.log( frustum.intersectsObject( object ) );