refactor(Sky.vue, Sparkles/component.vue): streamline instance exposure and remove unused refs

- Updated `Sky.vue` to directly expose the `skyImpl` instance instead of using a shallow reference, improving clarity and performance.
- Removed the unused `sparkleRef` in `Sparkles/component.vue`, simplifying the component structure while maintaining functionality.
- These changes enhance code maintainability and align with best practices for instance management in Vue components.

Author: alvarosabu

src/core/staging/Sky.vue

@@ -3,7 +3,7 @@ import { useTres } from '@tresjs/core'
 // eslint-disable-file vue/attribute-hyphenation
 import { MathUtils, Vector3 } from 'three'
 import { Sky as SkyImpl } from 'three-stdlib'
-import { computed, shallowRef, watch } from 'vue'
+import { computed, watch } from 'vue'
 
 export interface SkyProps {
   /**
@@ -53,7 +53,6 @@ watch(props, () => {
   invalidate()
 })
 
-const skyRef = shallowRef<SkyImpl>()
 const skyImpl = new SkyImpl()
 const sunPosition = computed(() =>
   getSunPosition(props.azimuth, props.elevation),
@@ -66,14 +65,13 @@ function getSunPosition(azimuth: number, elevation: number) {
 }
 
 defineExpose({
-  instance: skyRef,
+  instance: skyImpl,
   sunPosition: sunPosition.value,
 })
 </script>
 
 <template>
   <primitive
-    ref="skyRef"
     :object="skyImpl"
     :material-uniforms-turbidity-value="props.turbidity"
     :material-uniforms-rayleigh-value="props.rayleigh"

src/core/staging/Sparkles/component.vue

@@ -323,6 +323,8 @@ const shaderMaterialParameters: ShaderMaterialParameters = {
 const mat = new ShaderMaterial(shaderMaterialParameters)
 const sparkles = new Points(undefined, mat)
 
+defineExpose({ instance: sparkles })
+
 const u = mat.uniforms
 const NOW = { immediate: true }
 
@@ -414,11 +416,8 @@ onUnmounted(() => {
   infoTexture.value.dispose()
   mat.dispose()
 })
-
-const sparkleRef = shallowRef()
-defineExpose({ instance: sparkles })
 </script>
 
 <template>
-  <primitive ref="sparkleRef" :object="sparkles" />
+  <primitive :object="sparkles" />
 </template>