Converting Ping-Pong FBO to React Three Fiber

Yes, you can definitely convert this ping-pong FBO technique to work with React Three Fiber. The useFBO hook from drei is indeed powerful enough to support ping-pong FBO techniques, but you'll need to set up the ping-pong mechanism yourself.

Here's how you could implement this in React Three Fiber:

Creating a Custom Hook for Ping-Pong FBO

JSXCopied
import { useEffect, useMemo, useRef } from 'react'
import { useFBO } from '@react-three/drei'
import { useFrame } from '@react-three/fiber'
import * as THREE from 'three'

export function usePingPongFBO({ width, height, simulationMaterial, renderMaterial }) {
  // Create two FBOs for ping-ponging
  const fbo1 = useFBO({
    width,
    height,
    minFilter: THREE.NearestFilter,
    magFilter: THREE.NearestFilter,
    format: THREE.RGBAFormat,
    type: THREE.FloatType
  })
  
  const fbo2 = useFBO({
    width,
    height,
    minFilter: THREE.NearestFilter,
    magFilter: THREE.NearestFilter,
    format: THREE.RGBAFormat,
    type: THREE.FloatType
  })

  // Scene and camera for simulation
  const scene = useMemo(() => new THREE.Scene(), [])
  const camera = useMemo(() => new THREE.OrthographicCamera(-1, 1, 1, -1, 0, 1), [])
  
  // Quad for rendering to FBO
  const quad = useMemo(() => {
    const geometry = new THREE.PlaneGeometry(2, 2)
    const mesh = new THREE.Mesh(geometry, simulationMaterial)
    scene.add(mesh)
    return mesh
  }, [scene, simulationMaterial])
  
  // Track which FBO is the current source
  const pingPong = useRef(true)
  
  // Run the simulation each frame
  useFrame(({ gl }) => {
    const source = pingPong.current ? fbo1 : fbo2
    const target = pingPong.current ? fbo2 : fbo1
    
    // Set the source texture as a uniform for the simulation
    simulationMaterial.uniforms.tSource.value = source.texture
    
    // Render to the target FBO
    gl.setRenderTarget(target)
    gl.render(scene, camera)
    gl.setRenderTarget(null)
    
    // Update the render material with the latest simulation result
    renderMaterial.uniforms.tMap.value = target.texture
    
    // Flip for next frame
    pingPong.current = !pingPong.current
  })
  
  // Return the render material that has the latest simulation result
  return renderMaterial
}

Using the Custom Hook in a Component

JSXCopied
import React, { useMemo } from 'react'
import { Canvas } from '@react-three/fiber'
import { usePingPongFBO } from './usePingPongFBO'
import * as THREE from 'three'

function ParticleSystem() {
  // Create simulation material
  const simulationMaterial = useMemo(() => {
    return new THREE.ShaderMaterial({
      uniforms: {
        tSource: { value: null },
        // Add other uniforms as needed
      },
      vertexShader: /* your vertex shader */,
      fragmentShader: /* your simulation fragment shader */
    })
  }, [])
  
  // Create render material
  const renderMaterial = useMemo(() => {
    return new THREE.ShaderMaterial({
      uniforms: {
        tMap: { value: null },
        // Add other uniforms as needed
      },
      vertexShader: /* your vertex shader */,
      fragmentShader: /* your render fragment shader */
    })
  }, [])
  
  // Use the ping-pong FBO hook
  const material = usePingPongFBO({
    width: 512,
    height: 512,
    simulationMaterial,
    renderMaterial
  })
  
  // Create particle geometry
  const geometry = useMemo(() => {
    // Create your particle geometry here
    return new THREE.BufferGeometry()
  }, [])
  
  return <points geometry={geometry} material={material} />
}

export default function App() {
  return (
    <Canvas>
      <ParticleSystem />
    </Canvas>
  )
}

Additional Considerations

1. You'll need to adapt the specific implementation details from the original FBO class, such as checkHardware(), createTarget(), etc.

2. The WebGLRenderTarget is managed by the useFBO hook, which simplifies the code.

3. You might need to adjust the shader code to work with React Three Fiber's coordinate system.

4. For more complex scenarios, you might need to use useRef to store and update additional state.

This approach should give you a good starting point for implementing ping-pong FBOs in React Three Fiber. Let me know if you need more specific details about any part of the implementation!