From 8a8db47f6c1be032cffb4f623cc197945894467f Mon Sep 17 00:00:00 2001
From: Antoine Pilote <antoinepilote1@hotmail.com>
Date: Wed, 12 Jul 2023 16:10:20 -0400
Subject: [PATCH] Added lookat

---
 Editor/resources/Scripts/Scene.wren       |  4 ++
 Nuake/src/Core/Maths.cpp                  | 48 ++++++++++++++++++++++-
 Nuake/src/Core/Maths.h                    |  2 +
 Nuake/src/Scripting/Modules/SceneModule.h | 16 ++++++++
 4 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/Editor/resources/Scripts/Scene.wren b/Editor/resources/Scripts/Scene.wren
index 4b870cbd..b6bfd84a 100644
--- a/Editor/resources/Scripts/Scene.wren
+++ b/Editor/resources/Scripts/Scene.wren
@@ -44,6 +44,7 @@ class Scene {
 	foreign static GetTranslation_(e)
 	foreign static SetTranslation_(e, x, y, z)
 	foreign static SetRotation_(e, x, y, z)
+	foreign static SetLookAt_(e, x, y, z)
 	foreign static GetRotation_(e)
 	//foreign static SetScale_(e, x, y, z)
 
@@ -111,6 +112,9 @@ class TransformComponent {
 		Scene.SetRotation_(_entityId, t.x, t.y, t.z)
 	}
 
+	SetLookAt(t) {
+		Scene.SetLookAt_(_entityId, t.x, t.y, t.z)
+	}
 }
 
 class Light {
diff --git a/Nuake/src/Core/Maths.cpp b/Nuake/src/Core/Maths.cpp
index f77709c5..971339eb 100644
--- a/Nuake/src/Core/Maths.cpp
+++ b/Nuake/src/Core/Maths.cpp
@@ -2,9 +2,55 @@
 
 using namespace Nuake;
 
+Quat Nuake::LookAt(Vector3 sourcePoint, Vector3 destPoint)
+{
+    Vector3 forwardVector = glm::normalize(destPoint - sourcePoint);
+
+    float dot = glm::dot(Vector3(0, 0, 1), forwardVector);
+    if (glm::abs(dot - (-1.0f)) < 0.000001f)
+    {
+        return Quat(0, 1, 0, 3.1415926535897932f);
+    }
+    if (glm::abs(dot - (1.0f)) < 0.000001f)
+    {
+        return Quat(); // identity
+    }
+
+    float rotAngle = acos(dot);
+    Vector3 rotAxis = glm::cross(Vector3(0, 0, 1), forwardVector);
+    rotAxis = glm::normalize(rotAxis);
+    return CreateFromAxisAngle(rotAxis, rotAngle);
+}
+
+// just in case you need that function also
+Quat Nuake::CreateFromAxisAngle(Vector3 axis, float angle)
+{
+    float halfAngle = angle * .5f;
+    float s = sin(halfAngle);
+    Quat q;
+    q.x = axis.x * s;
+    q.y = axis.y * s;
+    q.z = axis.z * s;
+    q.w = cos(halfAngle);
+    return q;
+}
+
 Quat Nuake::QuatFromEuler(float x, float y, float z)
 {
-	return Quat(Vector3(Rad(z), Rad(y), Rad(x)));
+    Quat q;
+
+    float cr = cos(x * 0.5);
+    float sr = sin(x * 0.5);
+    float cp = cos(y * 0.5);
+    float sp = sin(y * 0.5);
+    float cy = cos(z * 0.5);
+    float sy = sin(z * 0.5);
+
+    q.w = cr * cp * cy + sr * sp * sy;
+    q.x = sr * cp * cy - cr * sp * sy;
+    q.y = cr * sp * cy + sr * cp * sy;
+    q.z = cr * cp * sy - sr * sp * cy;
+    return q;
 }
 
 Vector3 Nuake::QuatToDirection(const Quat& quat)
diff --git a/Nuake/src/Core/Maths.h b/Nuake/src/Core/Maths.h
index c16fba0e..13a91871 100644
--- a/Nuake/src/Core/Maths.h
+++ b/Nuake/src/Core/Maths.h
@@ -20,6 +20,8 @@ namespace Nuake
 	using Matrix3 = glm::mat3;
 #define Rad(degrees) glm::radians(degrees)
 
+	Quat LookAt(Vector3 sourcePoint, Vector3 destPoint);
+	Quat CreateFromAxisAngle(Vector3 axis, float angle);
 	Quat QuatFromEuler(float x, float y, float z);
 	Vector3 QuatToDirection(const Quat& quat);
 }
diff --git a/Nuake/src/Scripting/Modules/SceneModule.h b/Nuake/src/Scripting/Modules/SceneModule.h
index 2e0087d7..fbaa0ac5 100644
--- a/Nuake/src/Scripting/Modules/SceneModule.h
+++ b/Nuake/src/Scripting/Modules/SceneModule.h
@@ -40,6 +40,8 @@ namespace Nuake {
 				RegisterMethod("SetTranslation_(_,_,_,_)", (void*)SetTranslation);
 				RegisterMethod("GetRotation_(_)", (void*)GetRotation);
 				RegisterMethod("SetRotation_(_,_,_,_)", (void*)SetRotation);
+				RegisterMethod("SetLookAt_(_,_,_,_)", (void*)SetLookAt);
+
 				RegisterMethod("SetLightIntensity_(_,_)", (void*)SetLightIntensity);
 				RegisterMethod("GetLightIntensity_(_)", (void*)GetLightIntensity);
 
@@ -263,6 +265,20 @@ namespace Nuake {
 				transform.SetLocalRotation(QuatFromEuler(x, y, z));
 			}
 
+			static void SetLookAt(WrenVM* vm)
+			{
+				double handle = wrenGetSlotDouble(vm, 1);
+				Entity ent = Entity((entt::entity)handle, Engine::GetCurrentScene().get());
+				auto& transform = ent.GetComponent<TransformComponent>();
+				// set the slots
+				float x = (float)wrenGetSlotDouble(vm, 2);
+				float y = (float)wrenGetSlotDouble(vm, 3);
+				float z = (float)wrenGetSlotDouble(vm, 4);
+				Vector3 targetPosition = Vector3(x, y, z);
+				Quat rotation = LookAt(transform.GetGlobalPosition(), transform.GetGlobalPosition() + targetPosition);
+				transform.SetLocalRotation(rotation);
+			}
+
 			static void SetTranslation(WrenVM* vm)
 			{
 				double handle = wrenGetSlotDouble(vm, 1);