Merge pull request #111424 from lawnjelly/span

[3.x] Add `Span` and some basic uses from `Geometry`.

core/cowdata.h

@@ -38,6 +38,7 @@
 #include "core/error_macros.h"
 #include "core/os/memory.h"
 #include "core/safe_refcount.h"
+#include "core/span.h"
 
 template <class T>
 class Vector;
@@ -132,6 +133,9 @@ public:
 		}
 	}
 
+	_FORCE_INLINE_ operator Span<T>() const { return Span<T>(ptr(), size()); }
+	_FORCE_INLINE_ Span<T> span() const { return operator Span<T>(); }
+
 	_FORCE_INLINE_ void clear() { resize(0); }
 	_FORCE_INLINE_ bool empty() const { return _ptr == nullptr; }
 

core/local_vector.h

@@ -35,6 +35,7 @@
 #include "core/os/memory.h"
 #include "core/pool_vector.h"
 #include "core/sort_array.h"
+#include "core/span.h"
 #include "core/vector.h"
 
 #include <type_traits>
@@ -283,6 +284,9 @@ public:
 		return ret;
 	}
 
+	_FORCE_INLINE_ Span<T> span() const { return Span(data, count); }
+	_FORCE_INLINE_ operator Span<T>() const { return span(); }
+
 	_FORCE_INLINE_ LocalVector() {}
 	_FORCE_INLINE_ LocalVector(const LocalVector &p_from) {
 		resize(p_from.size());
@@ -290,12 +294,21 @@ public:
 			data[i] = p_from.data[i];
 		}
 	}
+
+	LocalVector(const Span<T> &p_from) {
+		resize(p_from.size());
+		for (U i = 0; i < count; i++) {
+			data[i] = p_from[i];
+		}
+	}
+
 	LocalVector(const Vector<T> &p_from) {
 		resize(p_from.size());
 		for (U i = 0; i < count; i++) {
 			data[i] = p_from[i];
 		}
 	}
+
 	LocalVector(const PoolVector<T> &p_from) {
 		resize(p_from.size());
 		typename PoolVector<T>::Read r = p_from.read();

core/math/bvh.h

@@ -396,7 +396,7 @@ public:
 			return 0;
 		}
 
-		Vector<Vector3> convex_points = Geometry::compute_convex_mesh_points(&p_convex[0], p_convex.size());
+		Vector<Vector3> convex_points = Geometry::compute_convex_mesh_points(p_convex);
 		if (convex_points.size() == 0) {
 			return 0;
 		}

core/math/delaunay.h

@@ -31,6 +31,7 @@
 #ifndef DELAUNAY_H
 #define DELAUNAY_H
 
+#include "core/local_vector.h"
 #include "core/math/rect2.h"
 
 class Delaunay2D {
@@ -58,7 +59,7 @@ public:
 		}
 	};
 
-	static bool circum_circle_contains(const Vector<Vector2> &p_vertices, const Triangle &p_triangle, int p_vertex) {
+	static bool circum_circle_contains(const Span<Vector2> &p_vertices, const Triangle &p_triangle, int p_vertex) {
 		Vector2 p1 = p_vertices[p_triangle.points[0]];
 		Vector2 p2 = p_vertices[p_triangle.points[1]];
 		Vector2 p3 = p_vertices[p_triangle.points[2]];
@@ -77,7 +78,7 @@ public:
 		return d <= r;
 	}
 
-	static bool edge_compare(const Vector<Vector2> &p_vertices, const Edge &p_a, const Edge &p_b) {
+	static bool edge_compare(const Span<Vector2> &p_vertices, const Edge &p_a, const Edge &p_b) {
 		if (p_vertices[p_a.edge[0]].is_equal_approx(p_vertices[p_b.edge[0]]) && p_vertices[p_a.edge[1]].is_equal_approx(p_vertices[p_b.edge[1]])) {
 			return true;
 		}
@@ -89,12 +90,12 @@ public:
 		return false;
 	}
 
-	static Vector<Triangle> triangulate(const Vector<Vector2> &p_points) {
+	static Vector<Triangle> triangulate(const Span<Vector2> &p_points) {
-		Vector<Vector2> points = p_points;
+		LocalVector<Vector2> points(p_points);
 		Vector<Triangle> triangles;
 
 		Rect2 rect;
-		for (int i = 0; i < p_points.size(); i++) {
+		for (uint32_t i = 0; i < p_points.size(); i++) {
 			if (i == 0) {
 				rect.position = p_points[i];
 			} else {
@@ -111,7 +112,7 @@ public:
 
 		triangles.push_back(Triangle(p_points.size() + 0, p_points.size() + 1, p_points.size() + 2));
 
-		for (int i = 0; i < p_points.size(); i++) {
+		for (uint32_t i = 0; i < p_points.size(); i++) {
 			//std::cout << "Traitement du point " << *p << std::endl;
 			//std::cout << "_triangles contains " << _triangles.size() << " elements" << std::endl;
 
@@ -150,10 +151,12 @@ public:
 			}
 		}
 
+		int point_count = p_points.size();
+
 		for (int i = 0; i < triangles.size(); i++) {
 			bool invalid = false;
 			for (int j = 0; j < 3; j++) {
-				if (triangles[i].points[j] >= p_points.size()) {
+				if (triangles[i].points[j] >= point_count) {
 					invalid = true;
 					break;
 				}

core/math/geometry.cpp

@@ -1398,11 +1398,13 @@ bool Geometry::convex_hull_intersects_convex_hull(const Plane *p_planes_a, int p
 	return false;
 }
 
-Vector<Vector3> Geometry::compute_convex_mesh_points(const Plane *p_planes, int p_plane_count, real_t p_epsilon) {
+Vector<Vector3> Geometry::compute_convex_mesh_points(const Span<Plane> &p_planes, real_t p_epsilon) {
 	Vector<Vector3> points;
 
 	// Iterate through every unique combination of any three planes.
-	for (int i = p_plane_count - 1; i >= 0; i--) {
+	int plane_count = p_planes.size();
+
+	for (int i = plane_count - 1; i >= 0; i--) {
 		for (int j = i - 1; j >= 0; j--) {
 			for (int k = j - 1; k >= 0; k--) {
 				// Find the point where these planes all cross over (if they
@@ -1412,7 +1414,7 @@ Vector<Vector3> Geometry::compute_convex_mesh_points(const Plane *p_planes, int
 					// See if any *other* plane excludes this point because it's
 					// on the wrong side.
 					bool excluded = false;
-					for (int n = 0; n < p_plane_count; n++) {
+					for (int n = 0; n < plane_count; n++) {
 						if (n != i && n != j && n != k) {
 							real_t dist = p_planes[n].distance_to(convex_shape_point);
 							if (dist > p_epsilon) {

core/math/geometry.h

@@ -806,7 +806,7 @@ public:
 		return _polypath_offset(p_polygon, p_delta, p_join_type, p_end_type);
 	}
 
-	static Vector<int> triangulate_delaunay_2d(const Vector<Vector2> &p_points) {
+	static Vector<int> triangulate_delaunay_2d(const Span<Vector2> &p_points) {
 		Vector<Delaunay2D::Triangle> tr = Delaunay2D::triangulate(p_points);
 		Vector<int> triangles;
 
@@ -1017,7 +1017,7 @@ public:
 	};
 	static Vector<PackRectsResult> partial_pack_rects(const Vector<Vector2i> &p_sizes, const Size2i &p_atlas_size);
 
-	static Vector<Vector3> compute_convex_mesh_points(const Plane *p_planes, int p_plane_count, real_t p_epsilon = CMP_EPSILON);
+	static Vector<Vector3> compute_convex_mesh_points(const Span<Plane> &p_planes, real_t p_epsilon = CMP_EPSILON);
 	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 bool verify_indices(const int *p_indices, int p_num_indices, int p_num_vertices);

core/math/octree_definition.inc

@@ -1575,7 +1575,7 @@ OCTREE_FUNC(int)::cull_convex(const Vector<Plane> &p_convex, T **p_result_array,
 		return 0;
 	}
 
-	Vector<Vector3> convex_points = Geometry::compute_convex_mesh_points(&p_convex[0], p_convex.size());
+	Vector<Vector3> convex_points = Geometry::compute_convex_mesh_points(p_convex);
 	if (convex_points.size() == 0) {
 		return 0;
 	}

core/span.h

@@ -0,0 +1,220 @@
+/**************************************************************************/
+/*  span.h                                                                */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#pragma once
+
+#include "core/error_macros.h"
+#include "core/typedefs.h"
+
+// Equivalent of std::span.
+// Represents a view into a contiguous memory space.
+// DISCLAIMER: This data type does not own the underlying buffer. DO NOT STORE IT.
+//  Additionally, for the lifetime of the Span, do not resize the buffer, and do not insert or remove elements from it.
+//  Failure to respect this may lead to crashes or undefined behavior.
+template <typename T, class U = uint32_t>
+class Span {
+	const T *_ptr = nullptr;
+	U _len = 0;
+
+public:
+	static constexpr bool is_string = std::disjunction_v<
+			std::is_same<T, char>,
+			std::is_same<T, char16_t>,
+			std::is_same<T, char32_t>,
+			std::is_same<T, wchar_t>>;
+
+	_FORCE_INLINE_ constexpr Span() = default;
+
+	_FORCE_INLINE_ Span(const T *p_ptr, U p_len) :
+			_ptr(p_ptr), _len(p_len) {
+#ifdef DEBUG_ENABLED
+		// TODO In c++20, make this check run only in non-consteval, and make this constructor constexpr.
+		if (_ptr == nullptr && _len > 0) {
+			ERR_PRINT("Internal bug, please report: Span was created from nullptr with size > 0. Recovering by using size = 0.");
+			_len = 0;
+		}
+#endif
+	}
+
+	// Allows creating Span directly from C arrays and string literals.
+	template <size_t N>
+	_FORCE_INLINE_ constexpr Span(const T (&p_array)[N]) :
+			_ptr(p_array), _len(N) {
+		if constexpr (is_string) {
+			// Cut off the \0 terminator implicitly added to string literals.
+			if (N > 0 && p_array[N - 1] == '\0') {
+				_len--;
+			}
+		}
+	}
+
+	_FORCE_INLINE_ constexpr U size() const { return _len; }
+	_FORCE_INLINE_ constexpr bool is_empty() const { return _len == 0; }
+
+	_FORCE_INLINE_ constexpr const T *ptr() const { return _ptr; }
+
+	// NOTE: Span subscripts sanity check the bounds to avoid undefined behavior.
+	//       This is slower than direct buffer access and can prevent autovectorization.
+	//       If the bounds are known, use ptr() subscript instead.
+	_FORCE_INLINE_ constexpr const T &operator[](U p_idx) const {
+		CRASH_COND(p_idx >= _len);
+		return _ptr[p_idx];
+	}
+
+	_FORCE_INLINE_ constexpr const T *begin() const { return _ptr; }
+	_FORCE_INLINE_ constexpr const T *end() const { return _ptr + _len; }
+
+	template <typename T1>
+	_FORCE_INLINE_ constexpr Span<T1> reinterpret() const {
+		return Span<T1>(reinterpret_cast<const T1 *>(_ptr), _len * sizeof(T) / sizeof(T1));
+	}
+
+	// Algorithms.
+	constexpr int64_t find(const T &p_val, U p_from = 0) const;
+	constexpr int64_t find_sequence(const Span<T> &p_span, U p_from = 0) const;
+	constexpr int64_t rfind(const T &p_val, U p_from) const;
+	_FORCE_INLINE_ constexpr int64_t rfind(const T &p_val) const { return rfind(p_val, size() - 1); }
+	constexpr int64_t rfind_sequence(const Span<T> &p_span, U p_from) const;
+	_FORCE_INLINE_ constexpr int64_t rfind_sequence(const Span<T> &p_span) const { return rfind_sequence(p_span, size() - p_span.size()); }
+	constexpr U count(const T &p_val) const;
+	/// Find the index of the given value using binary search.
+	/// Note: Assumes that elements in the span are sorted. Otherwise, use find() instead.
+	template <typename Comparator = Comparator<T>>
+	constexpr U bisect(const T &p_value, bool p_before, Comparator compare = Comparator()) const;
+
+	/// The caller is responsible to ensure size() > 0.
+	constexpr T max() const;
+};
+
+template <typename T, class U>
+constexpr int64_t Span<T, U>::find(const T &p_val, U p_from) const {
+	for (U i = p_from; i < size(); i++) {
+		if (ptr()[i] == p_val) {
+			return i;
+		}
+	}
+	return -1;
+}
+
+template <typename T, class U>
+constexpr int64_t Span<T, U>::find_sequence(const Span<T> &p_span, U p_from) const {
+	for (U i = p_from; i <= size() - p_span.size(); i++) {
+		bool found = true;
+		for (U j = 0; j < p_span.size(); j++) {
+			if (ptr()[i + j] != p_span.ptr()[j]) {
+				found = false;
+				break;
+			}
+		}
+		if (found) {
+			return i;
+		}
+	}
+
+	return -1;
+}
+
+template <typename T, class U>
+constexpr int64_t Span<T, U>::rfind(const T &p_val, U p_from) const {
+	for (int64_t i = p_from; i >= 0; i--) {
+		if (ptr()[i] == p_val) {
+			return i;
+		}
+	}
+	return -1;
+}
+
+template <typename T, class U>
+constexpr int64_t Span<T, U>::rfind_sequence(const Span<T> &p_span, U p_from) const {
+	for (int64_t i = p_from; i >= 0; i--) {
+		bool found = true;
+		for (U j = 0; j < p_span.size(); j++) {
+			if (ptr()[i + j] != p_span.ptr()[j]) {
+				found = false;
+				break;
+			}
+		}
+		if (found) {
+			return i;
+		}
+	}
+
+	return -1;
+}
+
+template <typename T, class U>
+constexpr U Span<T, U>::count(const T &p_val) const {
+	U amount = 0;
+	for (U i = 0; i < size(); i++) {
+		if (ptr()[i] == p_val) {
+			amount++;
+		}
+	}
+	return amount;
+}
+
+template <typename T, class U>
+template <typename Comparator>
+constexpr U Span<T, U>::bisect(const T &p_value, bool p_before, Comparator compare) const {
+	U lo = 0;
+	U hi = size();
+	if (p_before) {
+		while (lo < hi) {
+			const U mid = (lo + hi) / 2;
+			if (compare(ptr()[mid], p_value)) {
+				lo = mid + 1;
+			} else {
+				hi = mid;
+			}
+		}
+	} else {
+		while (lo < hi) {
+			const U mid = (lo + hi) / 2;
+			if (compare(p_value, ptr()[mid])) {
+				hi = mid;
+			} else {
+				lo = mid + 1;
+			}
+		}
+	}
+	return lo;
+}
+
+template <typename T, class U>
+constexpr T Span<T, U>::max() const {
+	DEV_ASSERT(size() > 0);
+	T max_val = _ptr[0];
+	for (U i = 1; i < _len; ++i) {
+		if (_ptr[i] > max_val) {
+			max_val = _ptr[i];
+		}
+	}
+	return max_val;
+}

core/vector.h

@@ -84,6 +84,10 @@ public:
 	_FORCE_INLINE_ const T &get(int p_index) const { return _cowdata.get(p_index); }
 	_FORCE_INLINE_ void set(int p_index, const T &p_elem) { _cowdata.set(p_index, p_elem); }
 	_FORCE_INLINE_ int size() const { return _cowdata.size(); }
+
+	_FORCE_INLINE_ operator Span<T>() const { return _cowdata.span(); }
+	_FORCE_INLINE_ Span<T> span() const { return _cowdata.span(); }
+
 	Error resize(int p_size) { return _cowdata.resize(p_size); }
 	_FORCE_INLINE_ const T &operator[](int p_index) const { return _cowdata.get(p_index); }
 	Error insert(int p_pos, T p_val) { return _cowdata.insert(p_pos, p_val); }

editor/spatial_editor_gizmos.cpp

@@ -536,7 +536,7 @@ bool EditorSpatialGizmo::intersect_frustum(const Camera *p_camera, const Vector<
 			transformed_frustum.push_back(it.xform(p_frustum[i]));
 		}
 
-		Vector<Vector3> convex_points = Geometry::compute_convex_mesh_points(p_frustum.ptr(), p_frustum.size());
+		Vector<Vector3> convex_points = Geometry::compute_convex_mesh_points(p_frustum);
 
 		if (collision_mesh->inside_convex_shape(transformed_frustum.ptr(), transformed_frustum.size(), convex_points.ptr(), convex_points.size(), mesh_scale)) {
 			return true;

scene/3d/room.cpp

@@ -172,7 +172,7 @@ PoolVector<Vector3> Room::generate_points() {
 	scaled_epsilon = MAX(scaled_epsilon * 0.01, 0.001);
 
 	LocalVector<Vector3, int32_t> pts;
-	pts = Geometry::compute_convex_mesh_points(&_planes[0], _planes.size(), scaled_epsilon);
+	pts = Geometry::compute_convex_mesh_points(Span<Plane>(_planes.ptr(), _planes.size()), scaled_epsilon);
 
 	// eliminate duplicates
 	for (int n = 0; n < pts.size(); n++) {

scene/3d/room_manager.cpp

@@ -784,7 +784,7 @@ void RoomManager::_generate_room_overlap_zones() {
 
 			memcpy(dest, &other->_planes[0], other->_planes.size() * sizeof(Plane));
 
-			Vector<Vector3> overlap_pts = Geometry::compute_convex_mesh_points(planes.ptr(), planes.size());
+			Vector<Vector3> overlap_pts = Geometry::compute_convex_mesh_points(Span<Plane>(planes.ptr(), planes.size()));
 
 			if (overlap_pts.size() < 4) {
 				continue;
@@ -1642,7 +1642,7 @@ void RoomManager::_build_simplified_bound(const Room *p_room, Geometry::MeshData
 		return;
 	}
 
-	Vector<Vector3> pts = Geometry::compute_convex_mesh_points(&r_planes[0], r_planes.size(), 0.001);
+	Vector<Vector3> pts = Geometry::compute_convex_mesh_points(Span<Plane>(r_planes.ptr(), r_planes.size()), 0.001);
 	Error err = _build_room_convex_hull(p_room, pts, r_md);
 
 	if (err != OK) {