Using CSS2DRenderer with Multiple Views in Three.js

You're encountering a common issue when using CSS2DRenderer with multiple views. The problem is that CSS2DRenderer manages its DOM elements based on the scene graph, and when you render the same scene with different cameras, the second renderer's operations can interfere with the first one.

Solution Approaches

1. Use Different Scene Objects for Each View

The most reliable approach is to use separate scene objects for each view:

JAVASCRIPTCopied
// Create two separate scenes
const scene1 = new THREE.Scene();
const scene2 = new THREE.Scene();

// Add your shared objects to both scenes
// For objects that should appear in both views
const sharedObject = new THREE.Mesh(...);
scene1.add(sharedObject.clone());
scene2.add(sharedObject.clone());

// Add view-specific labels to each scene
const label1 = new CSS2DObject(labelElement1);
const label2 = new CSS2DObject(labelElement2);
scene1.add(label1);
scene2.add(label2);

// In your render loop
view1Labels.render(scene1, view1Camera);
view2Labels.render(scene2, view2Camera);

2. Position and Size Adjustment

If you must use a single scene, you'll need to adjust the CSS2DRenderer's position and size to match your scissor regions:

JAVASCRIPTCopied
// Set up renderers with proper size
view1Labels.setSize(view1Width, view1Height);
view2Labels.setSize(view2Width, view2Height);

// In your render loop
// Before rendering labels, update positions to match scissor regions
view1Labels.domElement.style.position = 'absolute';
view1Labels.domElement.style.left = view1X + 'px';
view1Labels.domElement.style.top = view1Y + 'px';

view2Labels.domElement.style.position = 'absolute';
view2Labels.domElement.style.left = view2X + 'px';
view2Labels.domElement.style.top = view2Y + 'px';

// Then render
view1Labels.render(scene, view1Camera);
view2Labels.render(scene, view2Camera);

3. Use Object Visibility

Another approach is to toggle object visibility before rendering each view:

JAVASCRIPTCopied
// Create label groups
const view1LabelGroup = new THREE.Group();
const view2LabelGroup = new THREE.Group();
scene.add(view1LabelGroup);
scene.add(view2LabelGroup);

// Add labels to appropriate groups
view1LabelGroup.add(label1);
view2LabelGroup.add(label2);

// In your render loop
// Before rendering view 1
view1LabelGroup.visible = true;
view2LabelGroup.visible = false;
view1Labels.render(scene, view1Camera);

// Before rendering view 2
view1LabelGroup.visible = false;
view2LabelGroup.visible = true;
view2Labels.render(scene, view2Camera);

The first approach (separate scenes) is generally the most reliable for ensuring each view has its own independent set of labels without interference.