From 5aa98e895599827b1c0b7a1cc96d00fd78a9ff8b Mon Sep 17 00:00:00 2001
From: Relintai <relintai@protonmail.com>
Date: Sun, 20 Nov 2022 02:33:40 +0100
Subject: [PATCH] Added Brenzenham's line algorithm found in the
 TileMapEditorPlugin to Geometry, and it's binder class.

---
 core/bind/core_bind.cpp |  6 +++
 core/bind/core_bind.h   |  2 +
 core/math/geometry.h    | 92 +++++++++++++++++++++++++++++++++++++++--
 3 files changed, 97 insertions(+), 3 deletions(-)

diff --git a/core/bind/core_bind.cpp b/core/bind/core_bind.cpp
index 890871151..dd311d8fc 100644
--- a/core/bind/core_bind.cpp
+++ b/core/bind/core_bind.cpp
@@ -1889,6 +1889,10 @@ int _Geometry::get_uv84_normal_bit(const Vector3 &p_vector) {
 	return Geometry::get_uv84_normal_bit(p_vector);
 }
 
+PoolVector2iArray _Geometry::brenzenham_line(int x0, int x1, int y0, int y1) {
+	return Geometry::brenzenham_line_pv(x0, x1, y0, y1);
+}
+
 void _Geometry::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("build_box_planes", "extents"), &_Geometry::build_box_planes);
 	ClassDB::bind_method(D_METHOD("build_cylinder_planes", "radius", "height", "sides", "axis"), &_Geometry::build_cylinder_planes, DEFVAL(Vector3::AXIS_Z));
@@ -1936,6 +1940,8 @@ void _Geometry::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("make_atlas", "sizes"), &_Geometry::make_atlas);
 
+	ClassDB::bind_method(D_METHOD("brenzenham_line", "x0", "x1", "y0", "y1"), &_Geometry::brenzenham_line);
+
 	BIND_ENUM_CONSTANT(OPERATION_UNION);
 	BIND_ENUM_CONSTANT(OPERATION_DIFFERENCE);
 	BIND_ENUM_CONSTANT(OPERATION_INTERSECTION);
diff --git a/core/bind/core_bind.h b/core/bind/core_bind.h
index 5c56febaa..a78fe18e9 100644
--- a/core/bind/core_bind.h
+++ b/core/bind/core_bind.h
@@ -505,6 +505,8 @@ public:
 
 	Dictionary make_atlas(const Vector<Size2> &p_rects);
 
+	PoolVector2iArray brenzenham_line(int x0, int x1, int y0, int y1);
+
 	_Geometry();
 };
 
diff --git a/core/math/geometry.h b/core/math/geometry.h
index 78c923cc3..854ae2749 100644
--- a/core/math/geometry.h
+++ b/core/math/geometry.h
@@ -30,16 +30,16 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
 /*************************************************************************/
 
+#include "core/containers/pool_vector.h"
+#include "core/containers/vector.h"
 #include "core/math/delaunay.h"
 #include "core/math/face3.h"
 #include "core/math/rect2.h"
 #include "core/math/triangulate.h"
-#include "core/math/vector3.h"
 #include "core/math/vector2i.h"
+#include "core/math/vector3.h"
 #include "core/object/object.h"
-#include "core/containers/pool_vector.h"
 #include "core/string/print_string.h"
-#include "core/containers/vector.h"
 
 class Geometry {
 public:
@@ -1021,6 +1021,92 @@ public:
 	static bool convex_hull_intersects_convex_hull(const Plane *p_planes_a, int p_plane_count_a, const Plane *p_planes_b, int p_plane_count_b);
 	static real_t calculate_convex_hull_volume(const Geometry::MeshData &p_md);
 
+	static _FORCE_INLINE_ Vector<Point2i> brenzenham_line(int x0, int x1, int y0, int y1) {
+		Vector<Point2i> points;
+
+		float dx = ABS(x1 - x0);
+		float dy = ABS(y1 - y0);
+
+		int x = x0;
+		int y = y0;
+
+		int sx = x0 > x1 ? -1 : 1;
+		int sy = y0 > y1 ? -1 : 1;
+
+		if (dx > dy) {
+			float err = dx / 2;
+
+			for (; x != x1; x += sx) {
+				points.push_back(Vector2(x, y));
+
+				err -= dy;
+				if (err < 0) {
+					y += sy;
+					err += dx;
+				}
+			}
+		} else {
+			float err = dy / 2;
+
+			for (; y != y1; y += sy) {
+				points.push_back(Vector2(x, y));
+
+				err -= dx;
+				if (err < 0) {
+					x += sx;
+					err += dy;
+				}
+			}
+		}
+
+		points.push_back(Vector2(x, y));
+
+		return points;
+	}
+
+	static _FORCE_INLINE_ PoolVector2iArray brenzenham_line_pv(int x0, int x1, int y0, int y1) {
+		PoolVector2iArray points;
+
+		float dx = ABS(x1 - x0);
+		float dy = ABS(y1 - y0);
+
+		int x = x0;
+		int y = y0;
+
+		int sx = x0 > x1 ? -1 : 1;
+		int sy = y0 > y1 ? -1 : 1;
+
+		if (dx > dy) {
+			float err = dx / 2;
+
+			for (; x != x1; x += sx) {
+				points.push_back(Vector2(x, y));
+
+				err -= dy;
+				if (err < 0) {
+					y += sy;
+					err += dx;
+				}
+			}
+		} else {
+			float err = dy / 2;
+
+			for (; y != y1; y += sy) {
+				points.push_back(Vector2(x, y));
+
+				err -= dx;
+				if (err < 0) {
+					x += sx;
+					err += dy;
+				}
+			}
+		}
+
+		points.push_back(Vector2(x, y));
+
+		return points;
+	}
+
 private:
 	static Vector<Vector<Point2>> _polypaths_do_operation(PolyBooleanOperation p_op, const Vector<Point2> &p_polypath_a, const Vector<Point2> &p_polypath_b, bool is_a_open = false);
 	static Vector<Vector<Point2>> _polypath_offset(const Vector<Point2> &p_polypath, real_t p_delta, PolyJoinType p_join_type, PolyEndType p_end_type);