From 40ca0402d60142c106867c1400640ae237af7ce6 Mon Sep 17 00:00:00 2001
From: cosmonaut <evan@moonside.games>
Date: Thu, 10 Dec 2020 17:38:18 -0800
Subject: [PATCH] instance data struct

---
 Data/InstanceData.cs | 60 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 Data/InstanceData.cs

diff --git a/Data/InstanceData.cs b/Data/InstanceData.cs
new file mode 100644
index 0000000..97b7746
--- /dev/null
+++ b/Data/InstanceData.cs
@@ -0,0 +1,60 @@
+using System.Collections.Generic;
+using Microsoft.Xna.Framework.Graphics;
+
+namespace Kav
+{
+    public class InstanceData<T> where T : struct, IVertexType
+    {
+        public T[] InstanceDataArray { get; }
+        public DynamicVertexBuffer VertexBuffer { get; }
+        public int InstanceCount { get; private set; }
+
+        public InstanceData(GraphicsDevice graphicsDevice, int size)
+        {
+            InstanceDataArray = new T[size];
+
+            VertexBuffer = new DynamicVertexBuffer(
+                graphicsDevice,
+                typeof(T),
+                size,
+                BufferUsage.WriteOnly
+            );
+
+            InstanceCount = 0;
+        }
+
+        public void AddAndSetData(IEnumerable<T> data)
+        {
+            InstanceCount = 0;
+            foreach (var datum in data)
+            {
+                AddData(datum);
+            }
+
+            if (InstanceCount == 0) { throw new System.Exception(); }
+
+            SetData();
+        }
+
+        public void AddData(T datum)
+        {
+            InstanceDataArray[InstanceCount] = datum;
+            InstanceCount += 1;
+        }
+
+        public void SetData()
+        {
+            VertexBuffer.SetData(
+                InstanceDataArray,
+                0,
+                InstanceCount,
+                SetDataOptions.NoOverwrite
+            );
+        }
+
+        public void Clear()
+        {
+            InstanceCount = 0;
+        }
+    }
+}