feat: Autofocus effect (#192)

* feat(Autofocus): new effect

* fix1

* fix2: mdx doc

* tweaks

* fixes review drcmda

docs/effects/autofocus.mdx

@@ -0,0 +1,52 @@
+---
+title: Autofocus
+nav: 1
+---
+
+An auto-focus effect, that extends `<DepthOfField>`.
+
+Based on [ektogamat/AutoFocusDOF](https://github.com/ektogamat/AutoFocusDOF).
+
+```tsx
+export type AutofocusProps = typeof DepthOfField & {
+  target?: [number, number, number] // undefined
+  mouse?: boolean // false
+  debug?: number // undefined
+  manual?: boolean // false
+  smoothTime?: number // .25
+}
+```
+
+```tsx
+<EffectComposer>
+  <Autofocus />
+</EffectComposer>
+```
+
+Ref-api:
+
+```tsx
+type AutofocusApi = {
+  dofRef: RefObject<DepthOfFieldEffect>
+  hitpoint: THREE.Vector3
+  update: (delta: number, updateTarget: boolean) => void
+}
+```
+
+```tsx
+<Autofocus ref={autofocusRef} />
+```
+
+Associated with `manual` prop, you can for example, animate the DOF target yourself:
+
+```tsx
+useFrame((_, delta) => {
+  const api = autofocusRef.current
+  api.update(delta, false) // update hitpoint only
+  easing.damp3(api.dofRef.curent.target, api.hitpoint, 0.5, delta) // custom easing
+})
+```
+
+## Example
+
+<Codesandbox id="dfw6w4" />

package.json

@@ -45,6 +45,7 @@
     "release": "semantic-release"
   },
   "dependencies": {
+    "maath": "^0.5.3",
     "postprocessing": "^6.30.2",
     "screen-space-reflections": "2.5.0",
     "three-stdlib": "^2.21.10"

src/Autofocus.tsx

@@ -0,0 +1,139 @@
+import * as THREE from 'three'
+import React, {
+  useRef,
+  useContext,
+  useState,
+  useEffect,
+  useCallback,
+  forwardRef,
+  useImperativeHandle,
+  RefObject,
+} from 'react'
+import { useThree, useFrame, createPortal } from '@react-three/fiber'
+import { CopyPass, DepthPickingPass, DepthOfFieldEffect } from 'postprocessing'
+import { DepthOfField, EffectComposerContext } from './index'
+import { easing } from 'maath'
+
+export type AutofocusProps = typeof DepthOfField & {
+  target?: [number, number, number]
+  mouse?: boolean
+  debug?: number
+  manual?: boolean
+  smoothTime?: number
+}
+
+export type AutofocusApi = {
+  dofRef: RefObject<DepthOfFieldEffect>
+  hitpoint: THREE.Vector3
+  update: (delta: number, updateTarget: boolean) => void
+}
+
+export const Autofocus = forwardRef<AutofocusApi, AutofocusProps>(
+  (
+    { target = undefined, mouse: followMouse = false, debug = undefined, manual = false, smoothTime = 0, ...props },
+    fref
+  ) => {
+    const dofRef = useRef<DepthOfFieldEffect>(null)
+    const hitpointRef = useRef<THREE.Mesh>(null)
+    const targetRef = useRef<THREE.Mesh>(null)
+
+    const scene = useThree(({ scene }) => scene)
+    const pointer = useThree(({ pointer }) => pointer)
+    const { composer, camera } = useContext(EffectComposerContext)
+
+    // see: https://codesandbox.io/s/depthpickingpass-x130hg
+    const [depthPickingPass] = useState(new DepthPickingPass())
+    const [copyPass] = useState(new CopyPass())
+    useEffect(() => {
+      composer.addPass(depthPickingPass)
+      composer.addPass(copyPass)
+      return () => {
+        composer.removePass(depthPickingPass)
+        composer.removePass(copyPass)
+      }
+    }, [composer, depthPickingPass, copyPass])
+
+    const [hitpoint] = useState(new THREE.Vector3(0, 0, 0))
+
+    const [ndc] = useState(new THREE.Vector3(0, 0, 0))
+    const getHit = useCallback(
+      async (x: number, y: number) => {
+        ndc.x = x
+        ndc.y = y
+        ndc.z = await depthPickingPass.readDepth(ndc)
+        ndc.z = ndc.z * 2.0 - 1.0
+        const hit = 1 - ndc.z > 0.0000001 // it is missed if ndc.z is close to 1
+        return hit ? ndc.unproject(camera) : false
+      },
+      [ndc, depthPickingPass, camera]
+    )
+
+    const update = useCallback(
+      async (delta: number, updateTarget = true) => {
+        // Update hitpoint
+        if (target) {
+          hitpoint.set(...target)
+        } else {
+          const { x, y } = followMouse ? pointer : { x: 0, y: 0 }
+          const hit = await getHit(x, y)
+          if (hit) hitpoint.copy(hit)
+        }
+
+        // Update target
+        if (updateTarget && dofRef.current?.target) {
+          if (smoothTime > 0 && delta > 0) {
+            easing.damp3(dofRef.current.target, hitpoint, smoothTime, delta)
+          } else {
+            dofRef.current.target.copy(hitpoint)
+          }
+        }
+      },
+      [target, hitpoint, followMouse, getHit, smoothTime, pointer]
+    )
+
+    useFrame(async (_, delta) => {
+      if (!manual) {
+        update(delta)
+      }
+      if (hitpointRef.current) {
+        hitpointRef.current.position.copy(hitpoint)
+      }
+      if (targetRef.current && dofRef.current?.target) {
+        targetRef.current.position.copy(dofRef.current.target)
+      }
+    })
+
+    // Ref API
+    useImperativeHandle(
+      fref,
+      () => ({
+        dofRef,
+        hitpoint,
+        update,
+      }),
+      [hitpoint, update]
+    )
+
+    return (
+      <>
+        {debug
+          ? createPortal(
+              <>
+                <mesh ref={hitpointRef}>
+                  <sphereGeometry args={[debug, 16, 16]} />
+                  <meshBasicMaterial color="#00ff00" opacity={1} transparent depthWrite={false} />
+                </mesh>
+                <mesh ref={targetRef}>
+                  <sphereGeometry args={[debug / 2, 16, 16]} />
+                  <meshBasicMaterial color="#00ff00" opacity={0.5} transparent depthWrite={false} />
+                </mesh>
+              </>,
+              scene
+            )
+          : null}
+
+        <DepthOfField ref={dofRef} {...props} target={hitpoint} />
+      </>
+    )
+  }
+)

src/index.tsx

@@ -30,5 +30,6 @@ export * from './effects/TiltShift2'
 export * from './effects/SSR'
 
 export * from './Selection'
+export * from './Autofocus'
 export * from './EffectComposer'
 export * from './util'

yarn.lock

@@ -3338,6 +3338,11 @@ lru-cache@^9.0.0:
   resolved "https://registry.yarnpkg.com/lru-cache/-/lru-cache-9.1.1.tgz#c58a93de58630b688de39ad04ef02ef26f1902f1"
   integrity sha512-65/Jky17UwSb0BuB9V+MyDpsOtXKmYwzhyl+cOa9XUiI4uV2Ouy/2voFP3+al0BjZbJgMBD8FojMpAf+Z+qn4A==
 
+maath@^0.5.3:
+  version "0.5.3"
+  resolved "https://registry.yarnpkg.com/maath/-/maath-0.5.3.tgz#777a1f9b8463c6ffb199ea43406874a357c0cd58"
+  integrity sha512-ut63A4zTd9abtpi+sOHW1fPWPtAFrjK0E17eAthx1k93W/T2cWLKV5oaswyotJVDvvW1EXSdokAqhK5KOu0Qdw==
+
 magic-string@^0.27.0:
   version "0.27.0"
   resolved "https://registry.yarnpkg.com/magic-string/-/magic-string-0.27.0.tgz#e4a3413b4bab6d98d2becffd48b4a257effdbbf3"