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Assets/Packages/com.unity.uiextensions/Runtime/Scripts/Primitives/UILineRendererFIFO.cs

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+/// Credit Steve Westhoff, jack.sydorenko, firagon
+/// Sourced from - https://bitbucket.org/UnityUIExtensions/unity-ui-extensions/issues/324
+/// Refactored and updated for performance from UILineRenderer by Steve Westhoff
+
+using System.Collections.Generic;
+
+namespace UnityEngine.UI.Extensions
+{
+	[AddComponentMenu("UI/Extensions/Primitives/UILineRendererFIFO")]
+	[RequireComponent(typeof(RectTransform))]
+	public class UILineRendererFIFO : UIPrimitiveBase
+	{
+        private static readonly Vector2[] middleUvs = new[] { new Vector2(0.5f, 0), new Vector2(0.5f, 1), new Vector2(0.5f, 1), new Vector2(0.5f, 0) };
+        private List<Vector2> addedPoints = new List<Vector2>();
+        private bool needsResize;
+
+        [SerializeField, Tooltip("Thickness of the line")]
+        private float lineThickness = 1;
+
+		[SerializeField, Tooltip("Points to draw lines between\n Can be improved using the Resolution Option")]
+		private List<Vector2> points = new List<Vector2>();
+
+		[SerializeField, Tooltip("Segments to be drawn\n This is a list of arrays of points")]
+		private List<UIVertex[]> segments = new List<UIVertex[]>();
+
+        /// <summary>
+		/// Thickness of the line
+		/// </summary>
+		public float LineThickness
+        {
+            get { return lineThickness; }
+            set { lineThickness = value; SetAllDirty(); }
+        }
+
+        /// <summary>
+        /// Points to be drawn in the line.
+        /// </summary>
+        /// <remarks>Don't add points to the list directly, use the add / remove functions</remarks>
+        public List<Vector2> Points
+        {
+            get
+            {
+                return points;
+            }
+
+            set
+            {
+                if (points == value)
+                    return;
+                points = value;
+                SetAllDirty();
+            }
+        }
+
+        /// <summary>
+        /// Adds to head
+        /// </summary>
+        /// <param name="point"></param>
+        public void AddPoint(Vector2 point) {
+			points.Add(point);
+			addedPoints.Add(point);
+		}
+
+		/// <summary>
+		/// Removes from tail (FIFO)
+		/// </summary>
+		public void RemovePoint() {
+			points.RemoveAt(0);
+			needsResize = true;
+		}
+
+        /// <summary>
+		/// Clear all the points from the LineRenderer
+		/// </summary>
+		public void ClearPoints()
+        {
+            segments.Clear();
+            points.Clear();
+            addedPoints.Clear();
+            needsResize = false;
+        }
+
+        public void Resize() {
+			needsResize = true;
+		}
+
+		protected override void OnPopulateMesh(VertexHelper vertexHelper) {
+			vertexHelper.Clear();
+			if(needsResize) {
+				needsResize = false;
+				segments.Clear();
+				addedPoints = new List<Vector2>(points);
+			}
+			int count = addedPoints.Count;
+			if(count > 1) {
+				PopulateMesh(addedPoints, vertexHelper);
+				if(count % 2 == 0) {
+					addedPoints.Clear();
+				} else {
+					Vector2 extraPoint = addedPoints[count - 1];
+					addedPoints.Clear();
+					addedPoints.Add(extraPoint);
+				}
+			}
+		}
+
+		void PopulateMesh(List<Vector2> pointsToDraw, VertexHelper vertexHelper) {
+			if(ImproveResolution != ResolutionMode.None) {
+				pointsToDraw = IncreaseResolution(pointsToDraw);
+			}
+			float sizeX = rectTransform.rect.width;
+			float sizeY = rectTransform.rect.height;
+			float offsetX = -rectTransform.pivot.x * sizeX;
+			float offsetY = -rectTransform.pivot.y * sizeY;
+			for(int i = 1; i < pointsToDraw.Count; i += 2) {
+				Vector2 start = pointsToDraw[i - 1];
+				Vector2 end = pointsToDraw[i];
+				start = new Vector2(start.x * sizeX + offsetX, start.y * sizeY + offsetY);
+				end = new Vector2(end.x * sizeX + offsetX, end.y * sizeY + offsetY);
+				UIVertex[] segment = CreateLineSegment(start, end, segments.Count > 1 ? segments[segments.Count - 2] : null);
+				segments.Add(segment);
+			}
+			for(int i = 0; i < segments.Count; i++) {
+				vertexHelper.AddUIVertexQuad(segments[i]);
+			}
+			if(vertexHelper.currentVertCount > 64000) {
+				Debug.LogError("Max Verticies size is 64000, current mesh vertcies count is [" + vertexHelper.currentVertCount + "] - Cannot Draw");
+				vertexHelper.Clear();
+			}
+		}
+
+		UIVertex[] CreateLineSegment(Vector2 start, Vector2 end, UIVertex[] previousVert = null) {
+			Vector2 offset = new Vector2(start.y - end.y, end.x - start.x).normalized * lineThickness * 0.5f;
+			Vector2 v1;
+			Vector2 v2;
+			if(previousVert != null) {
+				v1 = new Vector2(previousVert[3].position.x, previousVert[3].position.y);
+				v2 = new Vector2(previousVert[2].position.x, previousVert[2].position.y);
+			} else {
+				v1 = start - offset;
+				v2 = start + offset;
+			}
+			return SetVbo(new[] { v1, v2, end + offset, end - offset }, middleUvs);
+		}
+	}
+}