Replaces cooldown circle (#956)

Content.Client/UserInterface/CooldownGraphic.cs

@@ -0,0 +1,33 @@
+using Robust.Client.Graphics.Drawing;
+using Robust.Client.Interfaces.GameObjects.Components;
+using Robust.Client.Interfaces.Graphics;
+using Robust.Shared.Maths;
+using System;
+
+namespace Robust.Client.UserInterface.Controls
+{
+    public class CooldownGraphic : Control
+    {
+        public float Fraction { get; set; }
+
+        protected override void Draw(DrawingHandleScreen handle)
+        {
+            const int maxSegments = 64;
+            const float segment = MathHelper.TwoPi / maxSegments;
+
+            var segments = (int)Math.Max(2, Math.Ceiling(maxSegments * Fraction)); // ensure that we always have 3 vertices
+            var max = MathHelper.TwoPi * Fraction;
+            var radius = (Math.Min(SizeBox.Height, SizeBox.Width) / 2) * 0.875f; // 28/32 = 0.875 - 2 pixels inwards from the edge
+
+            Span<Vector2> vertices = stackalloc Vector2[segments + 1];
+            vertices[0] = PixelPosition + SizeBox.Center;
+            for (int i = 0; i < segments; i++)
+            {
+                var angle = MathHelper.Pi + Math.Min(max, segment * i);
+                vertices[i + 1] = vertices[0] + new Vector2((float) Math.Sin(angle) * radius, (float) Math.Cos(angle) * radius);
+            }
+
+            handle.DrawPrimitives(DrawPrimitiveTopology.TriangleFan, vertices, new Color(0.3f, 0.3f, 0.4f, 0.5f));
+        }
+    }
+}