basic setup

composables/useScrollProgress.js

@@ -0,0 +1,46 @@
+import {
+    useElementBounding,
+    useIntersectionObserver,
+    useWindowSize,
+} from '@vueuse/core'
+import { ref } from 'vue'
+import { mapRange, clamp } from '@/libs/math'
+import useLenis from '@/composables/useLenis'
+
+const { height: wHeight } = useWindowSize()
+
+export const useScrollProgress = (el, callback, entry = 0.5, exit = 0.5) => {
+    const isActive = ref(true)
+    const smoothProgress = ref(0)
+
+    const { height, top } = useElementBounding(el)
+
+    const isIntersected = ref(false)
+    const { stop } = useIntersectionObserver(el, ([{ isIntersecting }]) => {
+        isIntersected.value = isIntersecting
+    })
+
+    useLenis(({ scroll }) => {
+        if (!isActive.value) return
+        if (!height.value || !wHeight.value) return
+        if (!isIntersected.value) return
+
+        const pageTop = scroll + top.value
+
+        const start = pageTop - wHeight.value * entry
+        const end = pageTop + height.value - wHeight.value * exit
+
+        let rawProgress = mapRange(start, end, scroll, 0, 1)
+        rawProgress = clamp(0, rawProgress, 1)
+
+        smoothProgress.value += (rawProgress - smoothProgress.value) * 0.1
+        callback?.(smoothProgress.value)
+    })
+
+    const destroy = () => {
+        isActive.value = false
+        stop?.()
+    }
+
+    return { destroy }
+}