From e239de52d68a1ab51003204109e884dc1e14ac05 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20L=C3=BCbe=C3=9F?= <simon.luebess@gmail.com>
Date: Fri, 20 Aug 2021 19:44:26 +0200
Subject: [PATCH] Added Line and Ray drawing

---
 GlitchyEngine/src/Renderer/Renderer.bf  | 92 ++++++++++++++++++++++++-
 Sandbox/content/Shaders/lineShader.hlsl | 31 +++++++++
 2 files changed, 122 insertions(+), 1 deletion(-)
 create mode 100644 Sandbox/content/Shaders/lineShader.hlsl

diff --git a/GlitchyEngine/src/Renderer/Renderer.bf b/GlitchyEngine/src/Renderer/Renderer.bf
index 5f1e4ca..4738b04 100644
--- a/GlitchyEngine/src/Renderer/Renderer.bf
+++ b/GlitchyEngine/src/Renderer/Renderer.bf
@@ -23,7 +23,11 @@ namespace GlitchyEngine.Renderer
 
 		static SceneConstants _sceneConstants;
 
-		public static void Init(GraphicsContext context)
+		static Effect LineEffect ~ _?.ReleaseRef();
+		static VertexBuffer LineVertices ~ _?.ReleaseRef();
+		static GeometryBinding LineGeometry ~ _?.ReleaseRef();
+
+		public static void Init(GraphicsContext context, EffectLibrary effectLibrary)
 		{
 			_context = context..AddRef();
 			/*
@@ -35,6 +39,32 @@ namespace GlitchyEngine.Renderer
 			*/
 
 			RenderCommand.Init();
+
+			InitLineRenderer(effectLibrary);
+		}
+
+		static void InitLineRenderer(EffectLibrary effectLibrary)
+		{
+			LineEffect = effectLibrary.Load("content\\Shaders\\lineShader.hlsl");
+
+			LineGeometry = new GeometryBinding(_context);
+			LineGeometry.SetPrimitiveTopology(.LineList);
+			
+			Vector4[2] vertices = .(.Zero, .Zero);
+			LineVertices = new VertexBuffer(_context, sizeof(Vector4), 2, .Dynamic, .Write);
+			LineVertices.SetData<Vector4>(vertices, 0, .WriteDiscard);
+			LineGeometry.SetVertexBufferSlot(LineVertices, 0);
+			
+			uint16[2] indices = .(0, 1);
+			IndexBuffer indexBuffer = new IndexBuffer(_context, 2, .Immutable);
+			indexBuffer.SetData(indices);
+			LineGeometry.SetIndexBuffer(indexBuffer);
+			indexBuffer.ReleaseRef();
+
+			VertexElement[] vertexElements = new VertexElement[1];
+			vertexElements[0] = .(.R32G32B32_Float, "POSITION");
+			VertexLayout layout = new VertexLayout(_context, vertexElements, true, LineEffect.VertexShader);
+			LineGeometry.SetVertexLayout(layout..ReleaseRefNoDelete());
 		}
 
 		public static void BeginScene(EcsWorld world, Entity cameraEntity)
@@ -88,5 +118,65 @@ namespace GlitchyEngine.Renderer
 			geometry.Bind();
 			RenderCommand.DrawIndexed(geometry);
 		}
+
+		/** @brief Draws a line.
+		 * @param start The start point of the line.
+		 * @param end The end point of the line.
+		 * @param color The color of the line.
+		 */
+		public static void DrawLine(Vector3 start, Vector3 end, Color color)
+		{
+			DrawLine(Vector4(start, 1.0f), Vector4(end, 1.0f), color, .Identity);
+		}
+		
+		/** @brief Draws a line.
+		 * @param start The start point of the line.
+		 * @param end The end point of the line.
+		 * @param color The color of the line.
+		 * @param transform A transform matrix transforming the line.
+		 */
+		public static void DrawLine(Vector3 start, Vector3 end, Color color, Matrix transform)
+		{
+			DrawLine(Vector4(start, 1.0f), Vector4(end, 1.0f), color, transform);
+		}
+		
+		/** @brief Draws a ray.
+		 * @param start The start point of the ray.
+		 * @param direction The direction of the ray.
+		 * @param color The color of the ray.
+		 */
+		public static void DrawRay(Vector3 start, Vector3 direction, Color color)
+		{
+			DrawLine(Vector4(start, 1.0f), Vector4(direction, 0.0f), color, .Identity);
+		}
+
+		/** @brief Draws a ray.
+		 * @param start The start point of the ray.
+		 * @param direction The direction of the ray.
+		 * @param color The color of the ray.
+		 * @param transform A transform matrix transforming the ray.
+		 */
+		public static void DrawRay(Vector3 start, Vector3 direction, Color color, Matrix transform)
+		{
+			DrawLine(Vector4(start, 1.0f), Vector4(direction, 0.0f), color, transform);
+		}
+		
+		/** @brief Draws a line.
+		 * @param start The start point of the line.
+		 * @param end The end point of the line.
+		 * @param color The color of the line.
+		 * @param transform A transform matrix transforming the line.
+		 */
+		public static void DrawLine(Vector4 start, Vector4 end, Color color, Matrix transform)
+		{
+			LineVertices.SetData(Vector4[2](start, end), 0, .WriteDiscard);
+			LineEffect.Variables["ViewProjection"].SetData(_sceneConstants.ViewProjection * transform);
+			LineEffect.Variables["Color"].SetData(color);
+
+			LineEffect.Bind(_context);
+
+			LineGeometry.Bind();
+			RenderCommand.DrawIndexed(LineGeometry);
+		}
 	}
 }
diff --git a/Sandbox/content/Shaders/lineShader.hlsl b/Sandbox/content/Shaders/lineShader.hlsl
new file mode 100644
index 0000000..1353f92
--- /dev/null
+++ b/Sandbox/content/Shaders/lineShader.hlsl
@@ -0,0 +1,31 @@
+cbuffer Constants : register(b0)
+{
+    float4x4 ViewProjection;
+    float4 Color;
+};
+
+struct VS_Input
+{
+    float4 Position : POSITION;
+};
+
+struct PS_Input
+{
+    float4 Position : SV_Position;
+};
+
+PS_Input VS(VS_Input input)
+{
+    PS_Input output;
+
+    output.Position = mul(ViewProjection, input.Position);
+
+    return output;
+}
+
+float4 PS(PS_Input input) : SV_Target0
+{
+    return Color;
+}
+
+#effect[VS=VS, PS=PS]