From 151e08ac18355099c170a914228cb9d817449af2 Mon Sep 17 00:00:00 2001
From: Yxure <93406322+Yxure@users.noreply.github.com>
Date: Thu, 18 Nov 2021 23:47:54 +0100
Subject: [PATCH] Fixed closed path rotation and added auto tilt checkbox

---
 scene/resources/curve.cpp | 41 +++++++++++++++++++++++++++++++++++++++
 scene/resources/curve.h   |  3 +++
 2 files changed, 44 insertions(+)

diff --git a/scene/resources/curve.cpp b/scene/resources/curve.cpp
index b530a72033cf..81331b81063a 100644
--- a/scene/resources/curve.cpp
+++ b/scene/resources/curve.cpp
@@ -1313,6 +1313,33 @@ void Curve3D::_bake() const {
 
 		idx++;
 	}
+
+	//Tilt smoothing, paralell rotation frame does not guarantee that the rotation at the beginning of the curve is equal to that at the end of the curve.
+	//Check out: Wang, W., Juttler, B., Zheng, D., and Liu, Y. 2008. Computation of rotation minimizing frame.
+
+	if (auto_tilts) {
+
+		//Calculate tilt angle difference between first and last baked up vector
+		Vector3 first_up = up_write[0];
+		Vector3 last_up = up_write[pointlist.size() - 1];
+		Vector3 tangent = Vector3(0, 0, 0);
+
+		for (int i = 0; i < idx; i++) {
+			tangent = (w[0] - w[i]);
+			if (tangent.length_squared() > CMP_EPSILON2) {
+				break;
+			}
+		}
+		tangent = tangent.normalized();
+		float phi = first_up.signed_angle_to(last_up, tangent);
+
+		for (int i = 0; i < idx; i++) {
+			wt[i] += phi * float(i) / float(idx - 1);
+		}
+	}
+
+
+
 }
 
 float Curve3D::get_baked_length() const {
@@ -1584,6 +1611,16 @@ bool Curve3D::is_up_vector_enabled() const {
 	return up_vector_enabled;
 }
 
+void Curve3D::set_auto_tilts(bool p_auto_tilts) {
+	auto_tilts = p_auto_tilts;
+	baked_cache_dirty = true;
+	emit_signal(CoreStringNames::get_singleton()->changed);
+}
+
+bool Curve3D::is_auto_tilts() const {
+	return auto_tilts;
+}
+
 Dictionary Curve3D::_get_data() const {
 	Dictionary dc;
 
@@ -1684,6 +1721,8 @@ void Curve3D::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_bake_interval"), &Curve3D::get_bake_interval);
 	ClassDB::bind_method(D_METHOD("set_up_vector_enabled", "enable"), &Curve3D::set_up_vector_enabled);
 	ClassDB::bind_method(D_METHOD("is_up_vector_enabled"), &Curve3D::is_up_vector_enabled);
+	ClassDB::bind_method(D_METHOD("set_auto_tilts", "enable"), &Curve3D::set_auto_tilts);
+	ClassDB::bind_method(D_METHOD("is_auto_tilts"), &Curve3D::is_auto_tilts);
 
 	ClassDB::bind_method(D_METHOD("get_baked_length"), &Curve3D::get_baked_length);
 	ClassDB::bind_method(D_METHOD("interpolate_baked", "offset", "cubic"), &Curve3D::interpolate_baked, DEFVAL(false));
@@ -1701,6 +1740,8 @@ void Curve3D::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "bake_interval", PROPERTY_HINT_RANGE, "0.01,512,0.01"), "set_bake_interval", "get_bake_interval");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "_data", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL), "_set_data", "_get_data");
 
+	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "auto_tilts"), "set_auto_tilts", "is_auto_tilts");
+
 	ADD_GROUP("Up Vector", "up_vector_");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "up_vector_enabled"), "set_up_vector_enabled", "is_up_vector_enabled");
 }
diff --git a/scene/resources/curve.h b/scene/resources/curve.h
index 5808fd650861..804ba51161d7 100644
--- a/scene/resources/curve.h
+++ b/scene/resources/curve.h
@@ -232,6 +232,7 @@ class Curve3D : public Resource {
 
 	float bake_interval = 0.2;
 	bool up_vector_enabled = true;
+	bool auto_tilts= true;
 
 	void _bake_segment3d(Map<float, Vector3> &r_bake, float p_begin, float p_end, const Vector3 &p_a, const Vector3 &p_out, const Vector3 &p_b, const Vector3 &p_in, int p_depth, int p_max_depth, float p_tol) const;
 	Dictionary _get_data() const;
@@ -261,6 +262,8 @@ class Curve3D : public Resource {
 	float get_bake_interval() const;
 	void set_up_vector_enabled(bool p_enable);
 	bool is_up_vector_enabled() const;
+	void set_auto_tilts(bool p_auto_tilts);
+	bool is_auto_tilts() const;
 
 	float get_baked_length() const;
 	Vector3 interpolate_baked(float p_offset, bool p_cubic = false) const;