Selection Highlighting Options for Three.js Room Planner

Based on your requirements for a clean and professional highlight effect in your Three.js room planner, I can recommend several approaches with their pros and cons.

Option 1: Enhanced BoxHelper/EdgesGeometry Approach

Your current implementation using EdgesGeometry is a good start. For a more polished look, you could:

1. Use THREE.BoxHelper instead of manually creating edges:

JAVASCRIPTCopied
import { BoxHelper } from 'three';

// In your component:
const boxHelperRef = useRef();

useEffect(() => {
  if (!selectedItem || !(selectedItem instanceof Mesh)) {
    if (boxHelperRef.current) boxHelperRef.current.visible = false;
    return;
  }
  
  if (!boxHelperRef.current) {
    boxHelperRef.current = new BoxHelper(selectedItem, 0x00bbff);
    scene.add(boxHelperRef.current);
  } else {
    boxHelperRef.current.visible = true;
    boxHelperRef.current.setFromObject(selectedItem);
  }
}, [selectedItem, scene]);

useFrame(() => {
  if (selectedItem && boxHelperRef.current) {
    boxHelperRef.current.setFromObject(selectedItem);
  }
});

Option 2: Outline Effect with EffectComposer

For a more sophisticated look, the OutlinePass from EffectComposer provides a professional glow effect:

JAVASCRIPTCopied
import { EffectComposer, OutlinePass } from 'three/examples/jsm/postprocessing/EffectComposer';
import { RenderPass } from 'three/examples/jsm/postprocessing/RenderPass';

// In your main component:
const { scene, camera, gl } = useThree();
const composer = useRef();
const outlinePass = useRef();

useEffect(() => {
  composer.current = new EffectComposer(gl);
  const renderPass = new RenderPass(scene, camera);
  composer.current.addPass(renderPass);
  
  outlinePass.current = new OutlinePass(
    new THREE.Vector2(window.innerWidth, window.innerHeight),
    scene, 
    camera
  );
  outlinePass.current.edgeStrength = 3.0;
  outlinePass.current.edgeGlow = 0.5;
  outlinePass.current.edgeThickness = 1.0;
  outlinePass.current.visibleEdgeColor.set('#00bbff');
  outlinePass.current.hiddenEdgeColor.set('#190a05');
  
  composer.current.addPass(outlinePass.current);
}, [scene, camera, gl]);

useEffect(() => {
  if (selectedItem && outlinePass.current) {
    outlinePass.current.selectedObjects = [selectedItem];
  } else if (outlinePass.current) {
    outlinePass.current.selectedObjects = [];
  }
}, [selectedItem]);

// Override the default render loop
useFrame(() => {
  composer.current.render();
}, 1);

With React Three Fiber, you can also use the @react-three/postprocessing package which provides a more declarative API:

JSXCopied
import { EffectComposer, Outline } from '@react-three/postprocessing';

// In your render function:
return (
  <>
    {/* Your scene components */}
    <EffectComposer>
      <Outline 
        selection={selectedItem ? [selectedItem] : []} 
        visibleEdgeColor="#00bbff"
        edgeStrength={3}
        edgeGlow={0.5}
        edgeThickness={1}
      />
    </EffectComposer>
  </>
);

Option 3: Custom Material Overlay

For a semi-transparent overlay effect:

JSXCopied
import { useEffect, useRef } from 'react';
import { Mesh, MeshBasicMaterial } from 'three';

function SelectionOverlay({ selectedItem }) {
  const overlayRef = useRef();
  
  useEffect(() => {
    if (!selectedItem || !overlayRef.current) return;
    
    // Clone the geometry
    overlayRef.current.geometry = selectedItem.geometry.clone();
    
    // Position the overlay
    overlayRef.current.position.copy(selectedItem.position);
    overlayRef.current.rotation.copy(selectedItem.rotation);
    overlayRef.current.scale.copy(selectedItem.scale);
    
    overlayRef.current.visible = true;
  }, [selectedItem]);
  
  useFrame(() => {
    if (!selectedItem || !overlayRef.current) {
      if (overlayRef.current) overlayRef.current.visible = false;
      return;
    }
    
    overlayRef.current.position.copy(selectedItem.position);
    overlayRef.current.rotation.copy(selectedItem.rotation);
    overlayRef.current.scale.copy(selectedItem.scale);
  });
  
  return (
    <mesh ref={overlayRef} visible={false}>
      <meshBasicMaterial 
        transparent={true} 
        opacity={0.3} 
        color="#00bbff" 
        depthTest={false}
      />
    </mesh>
  );
}

Recommendation

For the best balance of aesthetics and performance:

1. For simple scenes: Use the enhanced BoxHelper approach (Option 1) as it's lightweight and effective.

2. For professional-looking results: Use the OutlinePass with EffectComposer (Option 2), which provides a polished glow effect that works well for architectural visualization.

3. For complex scenes with many objects: Consider the custom material overlay (Option 3) as it can be more performant than post-processing when you have many objects.

The OutlinePass approach is generally the most visually appealing for room planners and architectural applications, though it does come with a slight performance cost.