feat: reset previous position on start play for world space simulation

close #303
mob-sakai · Jun 18, 2024 · 0130346 · 0130346
1 parent 1581ec5
commit 0130346
Showing 1 changed file with 11 additions and 9 deletions.
diff --git a/Packages/src/Runtime/UIParticleRenderer.cs b/Packages/src/Runtime/UIParticleRenderer.cs
@@ -37,8 +37,8 @@ internal class UIParticleRenderer : MaskableGraphic
         private UIParticle _parent;
         private ParticleSystem _particleSystem;
         private float _prevCanvasScale;
-        private Vector3 _prevPsPos;
-        private Vector3 _prevScale;
+        private Vector3? _prevPsPos;
+        private Vector3? _prevScale;
         private Vector2Int _prevScreenSize;
         private bool _prewarm;
         private ParticleSystemRenderer _renderer;
@@ -146,6 +146,8 @@ protected override void OnDisable()
             ModifiedMaterial.Remove(_modifiedMaterial);
             _modifiedMaterial = null;
             _currentMaterialForRendering = null;
+            _prevScale = null;
+            _prevPsPos = null;
         }
 
         public static UIParticleRenderer AddRenderer(UIParticle parent, int index)
@@ -296,7 +298,7 @@ public void UpdateMesh(Camera bakeCamera)
 #if UNITY_EDITOR
                 if (!Application.isPlaying)
                 {
-                    SimulateForEditor(psPos - _prevPsPos, scale);
+                    SimulateForEditor(psPos - _prevPsPos.GetValueOrDefault(), scale);
                 }
                 else
 #endif
@@ -581,7 +583,7 @@ private void ResolveResolutionChange(Vector3 psPos, Vector3 scale)
             var isWorldSpace = _particleSystem.IsWorldSpace();
             var canvasScale = _parent.canvas ? _parent.canvas.scaleFactor : 1f;
             var resolutionChanged = _prevScreenSize != screenSize || _prevCanvasScale != canvasScale;
-            if (resolutionChanged && isWorldSpace)
+            if (resolutionChanged && isWorldSpace && _prevPsPos.HasValue && _prevScale.HasValue)
             {
                 // Update particle array size and get particles.
                 var size = _particleSystem.particleCount;
@@ -592,8 +594,8 @@ private void ResolveResolutionChange(Vector3 psPos, Vector3 scale)
                 // (psPos / scale) / (prevPsPos / prevScale) -> psPos * scale.inv * prevPsPos.inv * prevScale
                 var modifier = psPos.GetScaled(
                     scale.Inverse(),
-                    _prevPsPos.Inverse(),
-                    _prevScale);
+                    _prevPsPos.Value.Inverse(),
+                    _prevScale.Value);
                 for (var i = 0; i < size; i++)
                 {
                     var particle = particles[i];
@@ -640,12 +642,12 @@ private void Simulate(Vector3 scale, bool paused)
             var rateOverDistance = emission.enabled
                                    && 0 < emission.rateOverDistance.constant
                                    && 0 < emission.rateOverDistanceMultiplier;
-            if (rateOverDistance && !paused)
+            if (rateOverDistance && !paused && _prevPsPos.HasValue && _prevScale.HasValue)
             {
                 // (For rate-over-distance emission,) Move to previous scaled position, simulate (delta = 0).
                 var prevScaledPos = isLocalSpace
-                    ? _prevPsPos
-                    : _prevPsPos.GetScaled(_prevScale.Inverse());
+                    ? _prevPsPos.Value
+                    : _prevPsPos.Value.GetScaled(_prevScale.Value.Inverse());
                 psTransform.SetPositionAndRotation(prevScaledPos, originWorldRotation);
                 _particleSystem.Simulate(0, false, false, false);
             }