add FlatWireframeGrid helper class

Blarg.GameFramework/Blarg.GameFramework.csproj

@@ -132,6 +132,7 @@
     <Compile Include="Graphics\CustomShaders\CustomVertexSkinningShader.cs" />
     <Compile Include="Graphics\SpriteBatch.cs" />
     <Compile Include="Graphics\BillboardSpriteBatch.cs" />
+    <Compile Include="Graphics\Helpers\FlatWireframeGrid.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets" />
   <ItemGroup>
@@ -145,6 +146,7 @@
     <Folder Include="Graphics\BuiltinShaders\" />
     <Folder Include="Support\" />
     <Folder Include="Graphics\CustomShaders\" />
+    <Folder Include="Graphics\Helpers\" />
   </ItemGroup>
   <ItemGroup>
     <EmbeddedResource Include="Resources\Fonts\Vera.ttf" />

Blarg.GameFramework/Graphics/Helpers/FlatWireframeGrid.cs

@@ -0,0 +1,63 @@
+using System;
+
+namespace Blarg.GameFramework.Graphics.Helpers
+{
+	public class FlatWireframeGrid
+	{
+		VertexBuffer _horizontalPoints;
+		VertexBuffer _verticalPoints;
+
+		public int Width { get; private set; }
+		public int Height { get; private set; }
+
+		public GraphicsDevice GraphicsDevice { get; private set; }
+
+		public FlatWireframeGrid(GraphicsDevice graphicsDevice, int width, int height)
+		{
+			if (graphicsDevice == null)
+				throw new ArgumentNullException("graphicsDevice");
+			if (width < 1)
+				throw new ArgumentOutOfRangeException("width");
+			if (height < 1)
+				throw new ArgumentOutOfRangeException("height");
+
+			GraphicsDevice = graphicsDevice;
+			Width = width;
+			Height = height;
+
+			_horizontalPoints = new VertexBuffer(GraphicsDevice, VertexAttributeDeclarations.ColorPosition3D, width * 2 + 2, BufferObjectUsage.Static);
+			_verticalPoints = new VertexBuffer(GraphicsDevice, VertexAttributeDeclarations.ColorPosition3D, height * 2 + 2, BufferObjectUsage.Static);
+
+			var gridColor = Color.White;
+
+			for (int i = 0; i < height + 1; ++i)
+			{
+				_horizontalPoints.SetPosition3D((i * 2), -(width / 2.0f), 0.0f, i - (height / 2.0f));
+				_horizontalPoints.SetColor((i * 2), ref gridColor);
+				_horizontalPoints.SetPosition3D((i * 2) + 1, width / 2.0f, 0.0f, i - (height / 2.0f));
+				_horizontalPoints.SetColor((i * 2) + 1, ref gridColor);
+			}
+
+			for (int i = 0; i < width + 1; ++i)
+			{
+				_verticalPoints.SetPosition3D((i * 2), i - (width / 2.0f), 0.0f, -(height / 2.0f));
+				_verticalPoints.SetColor((i * 2), ref gridColor);
+				_verticalPoints.SetPosition3D((i * 2) + 1, i - (width / 2.0f), 0.0f, height / 2.0f);
+				_verticalPoints.SetColor((i * 2) + 1, ref gridColor);
+			}
+		}
+
+		public void Render()
+		{
+			RenderState.Default.Apply();
+
+			GraphicsDevice.BindVertexBuffer(_horizontalPoints);
+			GraphicsDevice.RenderLines(0, _horizontalPoints.NumElements / 2);
+			GraphicsDevice.UnbindVertexBuffer();
+
+			GraphicsDevice.BindVertexBuffer(_verticalPoints);
+			GraphicsDevice.RenderLines(0, _verticalPoints.NumElements / 2);
+			GraphicsDevice.UnbindVertexBuffer();
+		}
+	}
+}