Dev Performance Instancing

Instanced Rendering

Render thousands of identical objects with a single draw call.

When to Use

Use when:

• Rendering many identical objects (trees, grass, particles)
• Draw calls exceed 100
• Objects share same geometry and material

Quick Start

import { Instances, Instance } from '@react-three/drei';

// Instead of 1000 separate meshes
function OptimizedTrees({ positions }) {
  return (
    <Instances limit={positions.length}>
      <cylinderGeometry args={[0.1, 0.3, 2]} />
      <meshStandardMaterial color="brown" />
      {positions.map((pos, i) => (
        <Instance key={i} position={pos} />
      ))}
    </Instances>
  );
}

Performance Impact

Dynamic Instancing

import { Instances, Instance } from '@react-three/drei';

function DynamicParticles({ count = 100 }) {
  const particles = useRef<Array<{ x: number; y: number; z: number }>>([]);

  // Initialize particles
  useMemo(() => {
    for (let i = 0; i < count; i++) {
      particles.current.push({
        x: (Math.random() - 0.5) * 10,
        y: (Math.random() - 0.5) * 10,
        z: (Math.random() - 0.5) * 10,
      });
    }
  }, [count]);

  return (
    <Instances limit={count}>
      <sphereGeometry args={[0.1, 8, 8]} />
      <meshBasicMaterial color="orange" />
      {particles.current.map((pos, i) => (
        <Instance key={i} position={[pos.x, pos.y, pos.z]} />
      ))}
    </Instances>
  );
}

Instancing with Colors

function ColoredInstances() {
  const colors = useMemo(() =>
    Array.from({ length: 100 }, () => ({
      color: new THREE.Color(Math.random(), Math.random(), Math.random()),
    }))
  , []);

  return (
    <Instances limit={100}>
      <boxGeometry args={[1, 1, 1]} />
      <meshStandardMaterial />
      {colors.map((props, i) => (
        <Instance
          key={i}
          position={[(i % 10) * 1.2, Math.floor(i / 10) * 1.2, 0]}
          color={props.color}
        />
      ))}
    </Instances>
  );
}

Limitations

Common Mistakes

When NOT to Use

• Objects have different geometries
• Objects have different materials
• Less than ~50 identical objects
• Objects need individual complex animations

Reference

• performance-basics.md - Core optimization
• lod-systems.md - LOD techniques

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