feat: add v-always-look-at directive

docs/.vitepress/config.ts

@@ -111,6 +111,7 @@ export default defineConfig({
         items: [
           { text: 'v-log', link: '/guide/directives/v-log' },
           { text: 'v-light-helper', link: '/guide/directives/v-light-helper' },
+          { text: 'v-always-look-at', link: '/guide/directives/v-always-look-at' },
         ],
       },
     ],

docs/guide/directives/v-always-look-at.md

@@ -0,0 +1,59 @@
+# v-always-look-at 👀
+
+With the new directive v-always-look-at provided by **TresJS**, you can add easily command an [Object3D](https://threejs.org/docs/index.html?q=object#api/en/core/Object3D) to always look at a specific position, this could be passed as a Vector3 or an Array.
+
+```vue{3}
+<script setup lang="ts">
+import { TresCanvas } from '@tresjs/core'
+import { Box, vAlwaysLookAt } from '@tresjs/cientos'
+</script>
+<template>
+    <TresCanvas >
+      <TresPerspectiveCamera :position="[0, 2, 5]" />
+      <Box
+        v-always-look-at="new Vector3(0, 0, 0)"
+      />
+  </TresCanvas>
+</template>
+```
+No matter where the Box move will always look-at the position [0,0,0]
+
+### Why not use the in built method look-at?
+
+You could ask, this is fine but I can use the :look-at method directly in the component, why should I need this?
+
+The answers is that with the method :look-at you will indicated to look at that position just once, when the instance is mounted, then if the object changes this will not get updated
+
+## You can look at other instance too!
+
+Another advantage is that you can look at an instance in movement, for example with the camera, like so:
+
+```vue{3}
+<script setup lang="ts">
+import { shallowRef } from 'vue'
+import { TresCanvas, useRenderLoop } from '@tresjs/core'
+import { Box, vAlwaysLookAt } from '@tresjs/cientos'
+
+const sphereRef = shallowRef()
+
+const { onLoop } = useRenderLoop()
+
+// here we update the position of the sphere and the camera will always follow the object
+onLoop(({ elapsed }) => {
+  if (sphereRef.value) {
+    sphereRef.value.value.position.y = Math.sin(elapsed) * 1.5
+  }
+})
+</script>
+<template>
+    <TresCanvas >
+      <TresPerspectiveCamera :position="[0, 2, 5]"
+        v-always-look-at="sphereRef"
+       />
+      <Sphere
+         ref="sphereRef"
+         :scale="0.5"
+       />
+  </TresCanvas>
+</template>
+```

playground/src/pages/directives/vAlwaysLookAt.vue

@@ -0,0 +1,60 @@
+<script setup lang="ts">
+import { shallowRef } from 'vue'
+import { TresCanvas, useRenderLoop } from '@tresjs/core'
+import { Stars, Sphere, Box, vAlwaysLookAt } from '@tresjs/cientos'
+import { SRGBColorSpace, NoToneMapping, Vector3 } from 'three'
+
+const gl = {
+  clearColor: '#333',
+  outputColorSpace: SRGBColorSpace,
+  toneMapping: NoToneMapping,
+}
+const sphereRef = shallowRef()
+const box1Ref = shallowRef()
+const box2Ref = shallowRef()
+
+const { onLoop } = useRenderLoop()
+
+onLoop(({ elapsed }) => {
+  if (sphereRef.value && box1Ref.value && box2Ref.value) {
+    sphereRef.value.value.position.y = Math.sin(elapsed) * 1.5
+    box2Ref.value.value.position.y = Math.sin(elapsed * 1.2) * 1.5 + 2
+    const boxAngle = elapsed * 0.75
+    box1Ref.value.value.position.x = Math.cos(boxAngle) * 5
+  }
+})
+</script>
+
+<template>
+  <TresCanvas v-bind="gl">
+    <!-- The camera observe a TresMesh -->
+    <TresPerspectiveCamera
+      v-always-look-at="sphereRef"
+      :position="[0, 2, 7.5]"
+    />
+    <Stars />
+    <Sphere
+      ref="sphereRef"
+      :scale="0.5"
+    />
+    <!-- This box use an array -->
+    <Box
+      ref="box1Ref"
+      v-always-look-at="[0, 0, 0]"
+      :color="0x00ff00"
+      :args="[1, 1, 0.1]"
+      name="greenBox"
+      :scale="1"
+      :position="[-2, 1, -3]"
+    />
+    <!-- This box use a Vector3 -->
+    <Box
+      ref="box2Ref"
+      v-always-look-at="new Vector3(0, 0, 0)"
+      :color="0xff0000"
+      :scale="1"
+      :position="[-2, 1, -3]"
+    />
+    <TresGridHelper :args="[10, 10]" />
+  </TresCanvas>
+</template>

playground/src/router/routes/directives.ts

@@ -9,4 +9,9 @@ export const directivesRoutes = [
     name: 'vLightHelper',
     component: () => import('../../pages/directives/vLightHelper.vue'),
   },
+  {
+    path: '/directives/v-always-look-at',
+    name: 'vAlwaysLookAt',
+    component: () => import('../../pages/directives/vAlwaysLookAt.vue'),
+  },
 ]

src/core/directives/index.ts

@@ -1,4 +1,5 @@
 import { vLog } from './vLog'
 import { vLightHelper } from './vLightHelper'
+import { vAlwaysLookAt } from './vAlwaysLookAt'
 
-export { vLog, vLightHelper }
+export { vLog, vLightHelper, vAlwaysLookAt }

src/core/directives/vAlwaysLookAt.ts

@@ -0,0 +1,19 @@
+import { useRenderLoop } from '@tresjs/core'
+import { Vector3 } from 'three'
+import type { Object3D } from 'three'
+
+export const vAlwaysLookAt = {
+  updated: (el: Object3D, binding: any) => {
+    let observer = binding.value
+    if (binding.value && binding.value?.value?.isMesh) {
+      observer = binding.value.value.position
+    }
+    if (Array.isArray(binding.value)) {
+      observer = new Vector3(...observer)
+    }
+    const { onLoop } = useRenderLoop()
+    onLoop(() => {
+      el.lookAt(observer)
+    })
+  },
+}