Combining Custom Vertex Shader with MeshReflectorMaterial

To deform a mesh using a custom vertex shader while still using the MeshReflectorMaterial from drei, you'll need to extend the material and inject your custom vertex shader code. Here's a solution that should work for your needs:

Approach: Extending MeshReflectorMaterial

You can use the onBeforeCompile callback of the material to inject your custom vertex shader code:

JSXCopied
import { MeshReflectorMaterial } from '@react-three/drei'
import { useRef, useEffect } from 'react'
import * as THREE from 'three'

// Your custom vertex shader code
const customVertexShader = `
  // Your deformation logic here
  vec4 modelPosition = modelMatrix * vec4(position, 1.0);
  
  // Example deformation (sine wave)
  modelPosition.y += sin(modelPosition.x * 10.0 + time) * 0.1;
  
  gl_Position = projectionMatrix * viewMatrix * modelPosition;
`

function DeformedReflector() {
  const materialRef = useRef()
  const timeRef = useRef({ value: 0 })
  
  useEffect(() => {
    if (materialRef.current) {
      // Add uniform for animation if needed
      materialRef.current.userData.time = timeRef.current
      
      // Original onBeforeCompile function
      const originalOnBeforeCompile = materialRef.current.onBeforeCompile
      
      materialRef.current.onBeforeCompile = (shader, renderer) => {
        // First run the original onBeforeCompile if it exists
        if (originalOnBeforeCompile) {
          originalOnBeforeCompile.call(materialRef.current, shader, renderer)
        }
        
        // Add custom uniform
        shader.uniforms.time = timeRef.current
        
        // Inject custom vertex code
        shader.vertexShader = shader.vertexShader.replace(
          'void main() {',
          `
          uniform float time;
          void main() {
          `
        )
        
        // Replace the position calculation
        shader.vertexShader = shader.vertexShader.replace(
          'gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );',
          customVertexShader
        )
      }
      
      // Make sure the material gets recompiled
      materialRef.current.needsUpdate = true
    }
  }, [])
  
  // Animation loop to update time
  useFrame((state) => {
    timeRef.current.value = state.clock.elapsedTime
  })
  
  return (
    <mesh rotation={[-Math.PI / 2, 0, 0]}>
      <planeGeometry args={[10, 10, 100, 100]} />
      <MeshReflectorMaterial
        ref={materialRef}
        resolution={512}
        mirror={0.5}
        mixBlur={10}
        mixStrength={1}
        blur={[300, 100]}
        metalness={0.6}
        roughness={0.4}
      />
    </mesh>
  )
}

Alternative: Using ShaderMaterial with MeshReflectorMaterial Features

If you need more control, you could create a custom shader material that incorporates both your deformation logic and the reflection features:

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

// Create a custom shader material
const CustomReflectorMaterial = shaderMaterial(
  {
    time: 0,
    reflectionMap: null,
    // Add other uniforms needed for reflection
  },
  // Vertex shader
  `
    uniform float time;
    varying vec2 vUv;
    varying vec3 vPosition;
    varying vec3 vNormal;
    
    void main() {
      vUv = uv;
      vPosition = position;
      vNormal = normal;
      
      // Your custom deformation
      vec4 modelPosition = modelMatrix * vec4(position, 1.0);
      modelPosition.y += sin(modelPosition.x * 10.0 + time) * 0.1;
      
      gl_Position = projectionMatrix * viewMatrix * modelPosition;
    }
  `,
  // Fragment shader
  `
    uniform sampler2D reflectionMap;
    varying vec2 vUv;
    varying vec3 vPosition;
    varying vec3 vNormal;
    
    void main() {
      // Sample reflection map
      vec4 reflection = texture2D(reflectionMap, vUv);
      
      // Your custom shading logic
      gl_FragColor = reflection;
    }
  `
)

// Extend for use in JSX
extend({ CustomReflectorMaterial })

// Then in your component
function DeformedReflector() {
  const materialRef = useRef()
  
  useFrame((state) => {
    if (materialRef.current) {
      materialRef.current.time = state.clock.elapsedTime
    }
  })
  
  // You would need to implement reflection rendering separately
  
  return (
    <mesh rotation={[-Math.PI / 2, 0, 0]}>
      <planeGeometry args={[10, 10, 100, 100]} />
      <customReflectorMaterial ref={materialRef} />
    </mesh>
  )
}

Loading External GLSL Files

If you prefer to keep your shader code in separate files:

JSXCopied
import { useEffect } from 'react'
import vertexShader from './vertex.glsl'

function DeformedReflector() {
  const materialRef = useRef()
  
  useEffect(() => {
    if (materialRef.current) {
      materialRef.current.onBeforeCompile = (shader) => {
        // Inject your external shader code
        shader.vertexShader = shader.vertexShader.replace(
          'gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );',
          vertexShader
        )
      }
      materialRef.current.needsUpdate = true
    }
  }, [])
  
  return (
    <mesh>
      <planeGeometry args={[10, 10, 100, 100]} />
      <MeshReflectorMaterial ref={materialRef} {...reflectorProps} />
    </mesh>
  )
}

The first approach using onBeforeCompile is likely the simplest solution for your needs, as it allows you to keep using MeshReflectorMaterial while adding your custom deformation logic.