From f87c0e2ecd7e1c45eca496b5e9cb7748bb3997b1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20L=C3=BCbe=C3=9F?= <simon.luebess@gmail.com>
Date: Tue, 2 Mar 2021 22:25:38 +0100
Subject: [PATCH] Raycasting world now returns intersection location and face

---
 Sandbox/src/VoxelFun/VoxelTestLayer.bf | 14 ++++++++++----
 Sandbox/src/VoxelFun/World.bf          | 24 +++++++++++++++++++++++-
 2 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/Sandbox/src/VoxelFun/VoxelTestLayer.bf b/Sandbox/src/VoxelFun/VoxelTestLayer.bf
index 6d20ab5..82ec78e 100644
--- a/Sandbox/src/VoxelFun/VoxelTestLayer.bf
+++ b/Sandbox/src/VoxelFun/VoxelTestLayer.bf
@@ -380,7 +380,7 @@ namespace Sandbox.VoxelFun
 				Renderer.Submit(_quadGeometryBinding, _effect, transform);
 			}
 			
-			_effect.Variables["BaseColor"].SetData(_squareColor1);
+			//_effect.Variables["BaseColor"].SetData(_squareColor1);
 			
 			_texture.Bind();
 			Renderer.Submit(_quadGeometryBinding, _textureEffect, .Scaling(1.5f));
@@ -392,8 +392,6 @@ namespace Sandbox.VoxelFun
 
 			//Ray ray = .(.(0.5f, 128.5f, 0.5f), .(0, -0.1f, -0.1f));
 
-			_effect.Variables["BaseColor"].SetData(.Red);
-
 			_texture.Bind();
 
 			Matrix mat = .Translation(ray.Start);
@@ -415,15 +413,21 @@ namespace Sandbox.VoxelFun
 			Renderer.Submit(_lineGeometryBinding, _textureEffect, mat3);
 
 			//Point3 lookedAtBlock = _world.RaycastBlock(ray, 10, _cubeGeo, _textureEffect);
-			Point3 lookedAtBlock = _world.RaycastBlock(.(_camera.Position, _camera.Transform.Forward), 10, _cubeGeo, _textureEffect);
+			Point3 lookedAtBlock = _world.RaycastBlock(.(_camera.Position, _camera.Transform.Forward), 10, _cubeGeo, _textureEffect, let intersection, let intersectFace);
+
+			intersectFace.ToString(intersectedFaceName..Clear());
 			
 			Renderer.Submit(_cubeGeo, _textureEffect, .Translation((Vector3)lookedAtBlock));
+			
+			Renderer.Submit(_cubeGeo, _textureEffect, .Translation(intersection) * .Scaling(0.1f) * .Translation(-0.5f, -0.5f, -0.5f));
 
 			_world.ChunkManager.Draw();
 
 			Renderer.EndScene();
 		}
 
+		String intersectedFaceName = new String() ~ delete _;
+
 		ColorRGBA _squareColor0 = ColorRGBA.CornflowerBlue;
 		ColorRGBA _squareColor1;
 
@@ -450,6 +454,8 @@ namespace Sandbox.VoxelFun
 
 			ImGui.Begin("Test");
 
+			ImGui.LabelText("Intersected Face", intersectedFaceName);
+
 			ImGui.DragFloat("Slow Speed", &movementSpeed, 1.0f, 0.01f, 100.0f);
 			ImGui.DragFloat("Fast Speed", &movementSpeedFast, 1.0f, 1f, 10000.0f);
 
diff --git a/Sandbox/src/VoxelFun/World.bf b/Sandbox/src/VoxelFun/World.bf
index 7cf8346..215e0ce 100644
--- a/Sandbox/src/VoxelFun/World.bf
+++ b/Sandbox/src/VoxelFun/World.bf
@@ -181,7 +181,7 @@ namespace Sandbox.VoxelFun
 			return Vector3.Floor(chunkPosition);
 		}
 
-		public Point3 RaycastBlock(Ray ray, float maxDistance, GeometryBinding geo, Effect effect)
+		public Point3 RaycastBlock(Ray ray, float maxDistance, GeometryBinding geo, Effect effect, out Vector3 intersectionPosition, out BlockFace intersectionFace)
 		{
 			Vector3 start = ray.Start;
 			Vector3 dir = ray.Direction.Normalized();
@@ -194,35 +194,45 @@ namespace Sandbox.VoxelFun
 
 			Point3 step;
 
+			BlockFace xFace;
+			BlockFace yFace;
+			BlockFace zFace;
+
 			if(dir.X < 0)
 			{
+				xFace = .Right;
 				step.X = -1;
 				rayLengths.X = (start.X - (float)(walker.X)) * unitStepSize.X;
 			}
 			else
 			{
+				xFace = .Left;
 				step.X = 1;
 				rayLengths.X = ((float)(walker.X + 1) - start.X) * unitStepSize.X;
 			}
 
 			if(dir.Y < 0)
 			{
+				yFace = .Top;
 				step.Y = -1;
 				rayLengths.Y = (start.Y - (float)(walker.Y)) * unitStepSize.Y;
 			}
 			else
 			{
+				yFace = .Bottom;
 				step.Y = 1;
 				rayLengths.Y = ((float)(walker.Y + 1) - start.Y) * unitStepSize.Y;
 			}
 			
 			if(dir.Z < 0)
 			{
+				zFace = .Back;
 				step.Z = -1;
 				rayLengths.Z = (start.Z - (float)(walker.Z)) * unitStepSize.Z;
 			}
 			else
 			{
+				zFace = .Front;
 				step.Z = 1;
 				rayLengths.Z = ((float)(walker.Z + 1) - start.Z) * unitStepSize.Z;
 			}
@@ -238,12 +248,16 @@ namespace Sandbox.VoxelFun
 						walker.X += step.X;
 						distance = rayLengths.X;
 						rayLengths.X += unitStepSize.X;
+
+						intersectionFace = xFace;
 					}
 					else
 					{
 						walker.Z += step.Z;
 						distance = rayLengths.Z;
 						rayLengths.Z += unitStepSize.Z;
+
+						intersectionFace = zFace;
 					}
 				}
 				else
@@ -253,12 +267,16 @@ namespace Sandbox.VoxelFun
 						walker.Y += step.Y;
 						distance = rayLengths.Y;
 						rayLengths.Y += unitStepSize.Y;
+
+						intersectionFace = yFace;
 					}
 					else
 					{
 						walker.Z += step.Z;
 						distance = rayLengths.Z;
 						rayLengths.Z += unitStepSize.Z;
+
+						intersectionFace = zFace;
 					}
 				}
 
@@ -272,11 +290,15 @@ namespace Sandbox.VoxelFun
 
 				if(blockData != 0)
 				{
+					intersectionPosition = start + distance * dir;
+
 					return walker;
 				}
 				
 			}
 
+			intersectionFace = .None;
+			intersectionPosition = .(float.NaN);
 			return .(int.MaxValue, int.MaxValue, int.MaxValue);
 		}
 	}