fix #23; In overlay, particle size is too small

UIParticle.cs

@@ -229,6 +229,7 @@ namespace Coffee.UIExtensions
 
 				if (m_ParticleSystem && canvas)
 				{
+					var rootCanvas = canvas.rootCanvas;
 					Profiler.BeginSample ("Disable ParticleSystemRenderer");
 					if (Application.isPlaying)
 					{
@@ -239,7 +240,7 @@ namespace Coffee.UIExtensions
 					Profiler.BeginSample ("Make Matrix");
 					scaleaMatrix = m_ParticleSystem.main.scalingMode == ParticleSystemScalingMode.Hierarchy
 					                               ? Matrix4x4.Scale (scale * Vector3.one)
-					                               : Matrix4x4.Scale (scale * canvas.rootCanvas.transform.localScale);
+					                               : Matrix4x4.Scale (scale * rootCanvas.transform.localScale);
 					Matrix4x4 matrix = default (Matrix4x4);
 					switch (m_ParticleSystem.main.simulationSpace)
 					{
@@ -263,13 +264,21 @@ namespace Coffee.UIExtensions
 					if (0 < m_ParticleSystem.particleCount)
 					{
 						Profiler.BeginSample ("Bake Mesh");
+						var cam = rootCanvas.renderMode == RenderMode.ScreenSpaceOverlay
+							? UIParticleOverlayCamera.GetCameraForOvrelay (rootCanvas)
+							: canvas.worldCamera ?? Camera.main;
+
+						if (!cam)
+						{
+							return;
+						}
 						if (m_IsTrail)
 						{
-							_renderer.BakeTrailsMesh (_mesh, true);
+							_renderer.BakeTrailsMesh (_mesh, cam, true);
 						}
 						else
 						{
-							_renderer.BakeMesh (_mesh, true);
+							_renderer.BakeMesh (_mesh, cam, true);
 						}
 						Profiler.EndSample ();
 

UIParticleOverlayCamera.cs

@@ -0,0 +1,110 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace Coffee.UIExtensions
+{
+	/// <summary>
+	/// </summary>
+	[ExecuteInEditMode]
+	public class UIParticleOverlayCamera : MonoBehaviour
+	{
+		//################################
+		// Public/Protected Members.
+		//################################
+		/// <summary>
+		/// Get instance object.
+		/// If instance does not exist, Find instance in scene, or create new one.
+		/// </summary>
+		public static UIParticleOverlayCamera instance
+		{
+			get
+			{
+				// Find instance in scene, or create new one.
+				if (object.ReferenceEquals (s_Instance, null))
+				{
+					s_Instance = FindObjectOfType<UIParticleOverlayCamera> () ?? new GameObject (typeof (UIParticleOverlayCamera).Name, typeof (UIParticleOverlayCamera)).GetComponent<UIParticleOverlayCamera> ();
+					s_Instance.gameObject.SetActive (true);
+					s_Instance.enabled = true;
+				}
+				return s_Instance;
+			}
+		}
+
+		public static Camera GetCameraForOvrelay (Canvas canvas)
+		{
+			var i = instance;
+			var rt = canvas.rootCanvas.transform as RectTransform;
+			var cam = i.cameraForOvrelay;
+			var trans = i.transform;
+			cam.enabled = false;
+
+			var pos = rt.localPosition;
+			cam.orthographic = true;
+			cam.orthographicSize = Mathf.Max (pos.x, pos.y);
+			cam.nearClipPlane = 0.3f;
+			cam.farClipPlane = 1000f;
+			pos.z -= 100;
+			trans.localPosition = pos;
+
+			return cam;
+		}
+
+		//################################
+		// Private Members.
+		//################################
+		Camera cameraForOvrelay { get { return m_Camera ? m_Camera : (m_Camera = GetComponent<Camera> ()) ? m_Camera : (m_Camera = gameObject.AddComponent<Camera> ()); } }
+		Camera m_Camera;
+		static UIParticleOverlayCamera s_Instance;
+
+		/// <summary>
+		/// Awake is called when the script instance is being loaded.
+		/// </summary>
+		void Awake ()
+		{
+			// Hold the instance.
+			if (s_Instance == null)
+			{
+				s_Instance = GetComponent<UIParticleOverlayCamera> ();
+			}
+			// If the instance is duplicated, destroy itself.
+			else if (s_Instance != this)
+			{
+				UnityEngine.Debug.LogWarning ("Multiple " + typeof (UIParticleOverlayCamera).Name + " in scene.", this.gameObject);
+				enabled = false;
+#if UNITY_EDITOR
+
+				if (!Application.isPlaying)
+				{
+					DestroyImmediate (gameObject);
+				}
+				else
+#endif
+				{
+					Destroy (gameObject);
+				}
+				return;
+			}
+
+			cameraForOvrelay.enabled = false;
+
+			// Singleton has DontDestroy flag.
+			if (Application.isPlaying)
+			{
+				DontDestroyOnLoad (gameObject);
+			}
+		}
+
+		/// <summary>
+		/// This function is called when the MonoBehaviour will be destroyed.
+		/// </summary>
+		void OnDestroy ()
+		{
+			// Clear instance on destroy.
+			if (s_Instance == this)
+			{
+				s_Instance = null;
+			}
+		}
+	}
+}

UIParticleOverlayCamera.cs.meta

@@ -0,0 +1,11 @@
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