godot/editor/plugins/curve_editor_plugin.cpp

/**************************************************************************/
/*  curve_editor_plugin.cpp                                               */
/**************************************************************************/
/*                         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.                  */
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#include "curve_editor_plugin.h"

#include "canvas_item_editor_plugin.h"
#include "core/input/input.h"
#include "core/math/geometry_2d.h"
#include "core/os/keyboard.h"
#include "editor/editor_interface.h"
#include "editor/editor_node.h"
#include "editor/editor_settings.h"
#include "editor/editor_string_names.h"
#include "editor/editor_undo_redo_manager.h"
#include "editor/gui/editor_spin_slider.h"
#include "editor/themes/editor_scale.h"
#include "scene/gui/flow_container.h"
#include "scene/gui/menu_button.h"
#include "scene/gui/popup_menu.h"
#include "scene/gui/separator.h"
#include "scene/resources/image_texture.h"

CurveEdit::CurveEdit() {
	set_focus_mode(FOCUS_ALL);
	set_clip_contents(true);
}

void CurveEdit::_bind_methods() {
	ClassDB::bind_method(D_METHOD("set_selected_index", "index"), &CurveEdit::set_selected_index);
}

void CurveEdit::set_curve(Ref<Curve> p_curve) {
	if (p_curve == curve) {
		return;
	}

	if (curve.is_valid()) {
		curve->disconnect_changed(callable_mp(this, &CurveEdit::_curve_changed));
		curve->disconnect(Curve::SIGNAL_RANGE_CHANGED, callable_mp(this, &CurveEdit::_curve_changed));
	}

	curve = p_curve;

	if (curve.is_valid()) {
		curve->connect_changed(callable_mp(this, &CurveEdit::_curve_changed));
		curve->connect(Curve::SIGNAL_RANGE_CHANGED, callable_mp(this, &CurveEdit::_curve_changed));
	}

	// Note: if you edit a curve, then set another, and try to undo,
	// it will normally apply on the previous curve, but you won't see it.
}

Ref<Curve> CurveEdit::get_curve() {
	return curve;
}

void CurveEdit::set_snap_enabled(bool p_enabled) {
	snap_enabled = p_enabled;
	queue_redraw();
	if (curve.is_valid()) {
		if (snap_enabled) {
			curve->set_meta(SNAME("_snap_enabled"), true);
		} else {
			curve->remove_meta(SNAME("_snap_enabled"));
		}
	}
}

void CurveEdit::set_snap_count(int p_snap_count) {
	snap_count = p_snap_count;
	queue_redraw();
	if (curve.is_valid()) {
		if (snap_count != CurveEditor::DEFAULT_SNAP) {
			curve->set_meta(SNAME("_snap_count"), snap_count);
		} else {
			curve->remove_meta(SNAME("_snap_count"));
		}
	}
}

Size2 CurveEdit::get_minimum_size() const {
	return Vector2(64, MAX(135, get_size().x * ASPECT_RATIO)) * EDSCALE;
}

void CurveEdit::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_MOUSE_EXIT: {
			if (hovered_index != -1 || hovered_tangent_index != TANGENT_NONE) {
				hovered_index = -1;
				hovered_tangent_index = TANGENT_NONE;
				queue_redraw();
			}
		} break;
		case NOTIFICATION_THEME_CHANGED:
		case EditorSettings::NOTIFICATION_EDITOR_SETTINGS_CHANGED: {
			float gizmo_scale = EDITOR_GET("interface/touchscreen/scale_gizmo_handles");
			point_radius = Math::round(BASE_POINT_RADIUS * get_theme_default_base_scale() * gizmo_scale);
			hover_radius = Math::round(BASE_HOVER_RADIUS * get_theme_default_base_scale() * gizmo_scale);
			tangent_radius = Math::round(BASE_TANGENT_RADIUS * get_theme_default_base_scale() * gizmo_scale);
			tangent_hover_radius = Math::round(BASE_TANGENT_HOVER_RADIUS * get_theme_default_base_scale() * gizmo_scale);
			tangent_length = Math::round(BASE_TANGENT_LENGTH * get_theme_default_base_scale());
		} break;
		case NOTIFICATION_DRAW: {
			_redraw();
		} break;
		case NOTIFICATION_VISIBILITY_CHANGED: {
			if (!is_visible()) {
				grabbing = GRAB_NONE;
			}
		} break;
	}
}

void CurveEdit::gui_input(const Ref<InputEvent> &p_event) {
	ERR_FAIL_COND(p_event.is_null());
	if (curve.is_null()) {
		return;
	}

	Ref<InputEventKey> k = p_event;
	if (k.is_valid()) {
		// Deleting points or making tangents linear.
		if (k->is_pressed() && k->get_keycode() == Key::KEY_DELETE) {
			if (selected_tangent_index != TANGENT_NONE) {
				toggle_linear(selected_index, selected_tangent_index);
			} else if (selected_index != -1) {
				if (grabbing == GRAB_ADD) {
					curve->remove_point(selected_index); // Point is temporary, so remove directly from curve.
					set_selected_index(-1);
				} else {
					remove_point(selected_index);
				}
				grabbing = GRAB_NONE;
				hovered_index = -1;
				hovered_tangent_index = TANGENT_NONE;
			}
			accept_event();
		}

		if (k->get_keycode() == Key::SHIFT || k->get_keycode() == Key::ALT) {
			queue_redraw(); // Redraw to show the axes or constraints.
		}
	}

	Ref<InputEventMouseButton> mb = p_event;
	if (mb.is_valid() && mb->is_pressed()) {
		Vector2 mpos = mb->get_position();

		if (mb->get_button_index() == MouseButton::RIGHT || mb->get_button_index() == MouseButton::MIDDLE) {
			if (mb->get_button_index() == MouseButton::RIGHT && grabbing == GRAB_MOVE) {
				// Move a point to its old position.
				curve->set_point_value(selected_index, initial_grab_pos.y);
				curve->set_point_offset(selected_index, initial_grab_pos.x);
				set_selected_index(initial_grab_index);
				hovered_index = get_point_at(mpos);
				grabbing = GRAB_NONE;
			} else {
				// Remove a point or make a tangent linear.
				selected_tangent_index = get_tangent_at(mpos);
				if (selected_tangent_index != TANGENT_NONE) {
					toggle_linear(selected_index, selected_tangent_index);
				} else {
					int point_to_remove = get_point_at(mpos);
					if (point_to_remove == -1) {
						set_selected_index(-1); // Nothing on the place of the click, just deselect the point.
					} else {
						if (grabbing == GRAB_ADD) {
							curve->remove_point(point_to_remove); // Point is temporary, so remove directly from curve.
							set_selected_index(-1);
						} else {
							remove_point(point_to_remove);
						}
						hovered_index = get_point_at(mpos);
						grabbing = GRAB_NONE;
					}
				}
			}
		}

		// Selecting or creating points.
		if (mb->get_button_index() == MouseButton::LEFT) {
			if (grabbing == GRAB_NONE) {
				selected_tangent_index = get_tangent_at(mpos);
				if (selected_tangent_index == TANGENT_NONE) {
					set_selected_index(get_point_at(mpos));
				}
				queue_redraw();
			}

			if (selected_index != -1) {
				// If an existing point/tangent was grabbed, remember a few things about it.
				grabbing = GRAB_MOVE;
				initial_grab_pos = curve->get_point_position(selected_index);
				initial_grab_index = selected_index;
				if (selected_index > 0) {
					initial_grab_left_tangent = curve->get_point_left_tangent(selected_index);
				}
				if (selected_index < curve->get_point_count() - 1) {
					initial_grab_right_tangent = curve->get_point_right_tangent(selected_index);
				}
			} else if (grabbing == GRAB_NONE) {
				// Adding a new point. Insert a temporary point for the user to adjust, so it's not in the undo/redo.
				Vector2 new_pos = get_world_pos(mpos).clamp(Vector2(0.0, curve->get_min_value()), Vector2(1.0, curve->get_max_value()));
				if (snap_enabled || mb->is_command_or_control_pressed()) {
					new_pos.x = Math::snapped(new_pos.x, 1.0 / snap_count);
					new_pos.y = Math::snapped(new_pos.y - curve->get_min_value(), curve->get_range() / snap_count) + curve->get_min_value();
				}

				new_pos.x = get_offset_without_collision(selected_index, new_pos.x, mpos.x >= get_view_pos(new_pos).x);

				// Add a temporary point for the user to adjust before adding it permanently.
				int new_idx = curve->add_point_no_update(new_pos);
				set_selected_index(new_idx);
				grabbing = GRAB_ADD;
				initial_grab_pos = new_pos;
			}
		}
	}

	if (mb.is_valid() && mb->get_button_index() == MouseButton::LEFT && !mb->is_pressed()) {
		if (selected_tangent_index != TANGENT_NONE) {
			// Finish moving a tangent control.
			if (selected_index == 0) {
				set_point_right_tangent(selected_index, curve->get_point_right_tangent(selected_index));
			} else if (selected_index == curve->get_point_count() - 1) {
				set_point_left_tangent(selected_index, curve->get_point_left_tangent(selected_index));
			} else {
				set_point_tangents(selected_index, curve->get_point_left_tangent(selected_index), curve->get_point_right_tangent(selected_index));
			}
			grabbing = GRAB_NONE;
		} else if (grabbing == GRAB_MOVE) {
			// Finish moving a point.
			set_point_position(selected_index, curve->get_point_position(selected_index));
			grabbing = GRAB_NONE;
		} else if (grabbing == GRAB_ADD) {
			// Finish inserting a new point. Remove the temporary point and insert a permanent one in its place.
			Vector2 new_pos = curve->get_point_position(selected_index);
			curve->remove_point(selected_index);
			add_point(new_pos);
			grabbing = GRAB_NONE;
		}
		queue_redraw();
	}

	Ref<InputEventMouseMotion> mm = p_event;
	if (mm.is_valid()) {
		Vector2 mpos = mm->get_position();

		if (grabbing != GRAB_NONE && curve.is_valid()) {
			if (selected_index != -1) {
				if (selected_tangent_index == TANGENT_NONE) {
					// Drag point.
					Vector2 new_pos = get_world_pos(mpos).clamp(Vector2(0.0, curve->get_min_value()), Vector2(1.0, curve->get_max_value()));

					if (snap_enabled || mm->is_command_or_control_pressed()) {
						new_pos.x = Math::snapped(new_pos.x, 1.0 / snap_count);
						new_pos.y = Math::snapped(new_pos.y - curve->get_min_value(), curve->get_range() / snap_count) + curve->get_min_value();
					}

					// Allow to snap to axes with Shift.
					if (mm->is_shift_pressed()) {
						Vector2 initial_mpos = get_view_pos(initial_grab_pos);
						if (Math::abs(mpos.x - initial_mpos.x) > Math::abs(mpos.y - initial_mpos.y)) {
							new_pos.y = initial_grab_pos.y;
						} else {
							new_pos.x = initial_grab_pos.x;
						}
					}

					// Allow to constraint the point between the adjacent two with Alt.
					if (mm->is_alt_pressed()) {
						float prev_point_offset = (selected_index > 0) ? (curve->get_point_position(selected_index - 1).x + 0.00001) : 0.0;
						float next_point_offset = (selected_index < curve->get_point_count() - 1) ? (curve->get_point_position(selected_index + 1).x - 0.00001) : 1.0;
						new_pos.x = CLAMP(new_pos.x, prev_point_offset, next_point_offset);
					}

					new_pos.x = get_offset_without_collision(selected_index, new_pos.x, mpos.x >= get_view_pos(new_pos).x);

					// The index may change if the point is dragged across another one.
					int i = curve->set_point_offset(selected_index, new_pos.x);
					hovered_index = i;
					set_selected_index(i);

					new_pos.y = CLAMP(new_pos.y, curve->get_min_value(), curve->get_max_value());
					curve->set_point_value(selected_index, new_pos.y);

				} else {
					// Drag tangent.

					const Vector2 new_pos = curve->get_point_position(selected_index);
					const Vector2 control_pos = get_world_pos(mpos);

					Vector2 dir = (control_pos - new_pos).normalized();
					real_t tangent = dir.y / (dir.x > 0 ? MAX(dir.x, 0.00001) : MIN(dir.x, -0.00001));

					// Must keep track of the hovered index as the cursor might move outside of the editor while dragging.
					hovered_tangent_index = selected_tangent_index;

					// Adjust the tangents.
					if (selected_tangent_index == TANGENT_LEFT) {
						curve->set_point_left_tangent(selected_index, tangent);

						// Align the other tangent if it isn't linear and Shift is not pressed.
						// If Shift is pressed at any point, restore the initial angle of the other tangent.
						if (selected_index != (curve->get_point_count() - 1) && curve->get_point_right_mode(selected_index) != Curve::TANGENT_LINEAR) {
							curve->set_point_right_tangent(selected_index, mm->is_shift_pressed() ? initial_grab_right_tangent : tangent);
						}

					} else {
						curve->set_point_right_tangent(selected_index, tangent);

						if (selected_index != 0 && curve->get_point_left_mode(selected_index) != Curve::TANGENT_LINEAR) {
							curve->set_point_left_tangent(selected_index, mm->is_shift_pressed() ? initial_grab_left_tangent : tangent);
						}
					}
				}
			}
		} else {
			// Grab mode is GRAB_NONE, so do hovering logic.
			hovered_index = get_point_at(mpos);
			hovered_tangent_index = get_tangent_at(mpos);
			queue_redraw();
		}
	}
}

void CurveEdit::use_preset(int p_preset_id) {
	ERR_FAIL_COND(p_preset_id < 0 || p_preset_id >= PRESET_COUNT);
	ERR_FAIL_COND(curve.is_null());

	Array previous_data = curve->get_data();
	curve->clear_points();

	float min_value = curve->get_min_value();
	float max_value = curve->get_max_value();

	switch (p_preset_id) {
		case PRESET_CONSTANT:
			curve->add_point(Vector2(0, (min_value + max_value) / 2.0));
			curve->add_point(Vector2(1, (min_value + max_value) / 2.0));
			curve->set_point_right_mode(0, Curve::TANGENT_LINEAR);
			curve->set_point_left_mode(1, Curve::TANGENT_LINEAR);
			break;

		case PRESET_LINEAR:
			curve->add_point(Vector2(0, min_value));
			curve->add_point(Vector2(1, max_value));
			curve->set_point_right_mode(0, Curve::TANGENT_LINEAR);
			curve->set_point_left_mode(1, Curve::TANGENT_LINEAR);
			break;

		case PRESET_EASE_IN:
			curve->add_point(Vector2(0, min_value));
			curve->add_point(Vector2(1, max_value), curve->get_range() * 1.4, 0);
			break;

		case PRESET_EASE_OUT:
			curve->add_point(Vector2(0, min_value), 0, curve->get_range() * 1.4);
			curve->add_point(Vector2(1, max_value));
			break;

		case PRESET_SMOOTHSTEP:
			curve->add_point(Vector2(0, min_value));
			curve->add_point(Vector2(1, max_value));
			break;

		default:
			break;
	}

	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
	undo_redo->create_action(TTR("Load Curve Preset"));
	undo_redo->add_do_method(*curve, "_set_data", curve->get_data());
	undo_redo->add_do_method(this, "set_selected_index", -1);
	undo_redo->add_undo_method(*curve, "_set_data", previous_data);
	undo_redo->add_undo_method(this, "set_selected_index", selected_index);
	undo_redo->commit_action();
}

void CurveEdit::_curve_changed() {
	queue_redraw();
	// Point count can change in case of undo.
	if (selected_index >= curve->get_point_count()) {
		set_selected_index(-1);
	}
}

int CurveEdit::get_point_at(Vector2 p_pos) const {
	if (curve.is_null()) {
		return -1;
	}

	// Use a square-shaped hover region. If hovering multiple points, pick the closer one.
	const Rect2 hover_rect = Rect2(p_pos, Vector2(0, 0)).grow(hover_radius);
	int closest_idx = -1;
	float closest_dist_squared = hover_radius * hover_radius * 2;

	for (int i = 0; i < curve->get_point_count(); ++i) {
		Vector2 p = get_view_pos(curve->get_point_position(i));
		if (hover_rect.has_point(p) && p.distance_squared_to(p_pos) < closest_dist_squared) {
			closest_dist_squared = p.distance_squared_to(p_pos);
			closest_idx = i;
		}
	}

	return closest_idx;
}

CurveEdit::TangentIndex CurveEdit::get_tangent_at(Vector2 p_pos) const {
	if (curve.is_null() || selected_index < 0) {
		return TANGENT_NONE;
	}

	const Rect2 hover_rect = Rect2(p_pos, Vector2(0, 0)).grow(tangent_hover_radius);

	if (selected_index != 0) {
		Vector2 control_pos = get_tangent_view_pos(selected_index, TANGENT_LEFT);
		if (hover_rect.has_point(control_pos)) {
			return TANGENT_LEFT;
		}
	}

	if (selected_index != curve->get_point_count() - 1) {
		Vector2 control_pos = get_tangent_view_pos(selected_index, TANGENT_RIGHT);
		if (hover_rect.has_point(control_pos)) {
			return TANGENT_RIGHT;
		}
	}

	return TANGENT_NONE;
}

// FIXME: This function should be bounded better.
float CurveEdit::get_offset_without_collision(int p_current_index, float p_offset, bool p_prioritize_right) {
	float safe_offset = p_offset;
	bool prioritizing_right = p_prioritize_right;

	for (int i = 0; i < curve->get_point_count(); i++) {
		if (i == p_current_index) {
			continue;
		}

		if (curve->get_point_position(i).x > safe_offset) {
			break;
		}

		if (curve->get_point_position(i).x == safe_offset) {
			if (prioritizing_right) {
				safe_offset += 0.00001;
				if (safe_offset > 1.0) {
					safe_offset = 1.0;
					prioritizing_right = false;
				}
			} else {
				safe_offset -= 0.00001;
				if (safe_offset < 0.0) {
					safe_offset = 0.0;
					prioritizing_right = true;
				}
			}
			i = -1;
		}
	}

	return safe_offset;
}

void CurveEdit::add_point(Vector2 p_pos) {
	ERR_FAIL_COND(curve.is_null());

	// Add a point to get its index, then remove it immediately. Trick to feed the UndoRedo.
	int new_idx = curve->add_point(p_pos);
	curve->remove_point(new_idx);

	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
	undo_redo->create_action(TTR("Add Curve Point"));
	undo_redo->add_do_method(*curve, "add_point", p_pos);
	undo_redo->add_do_method(this, "set_selected_index", new_idx);
	undo_redo->add_undo_method(*curve, "remove_point", new_idx);
	undo_redo->add_undo_method(this, "set_selected_index", -1);
	undo_redo->commit_action();
}

void CurveEdit::remove_point(int p_index) {
	ERR_FAIL_COND(curve.is_null());
	ERR_FAIL_INDEX_MSG(p_index, curve->get_point_count(), "Curve point is out of bounds.");

	Curve::Point p = curve->get_point(p_index);
	Vector2 old_pos = (grabbing == GRAB_MOVE) ? initial_grab_pos : p.position;

	int new_selected_index = selected_index;
	// Reselect the old selected point if it's not the deleted one.
	if (new_selected_index > p_index) {
		new_selected_index -= 1;
	} else if (new_selected_index == p_index) {
		new_selected_index = -1;
	}

	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
	undo_redo->create_action(TTR("Remove Curve Point"));
	undo_redo->add_do_method(*curve, "remove_point", p_index);
	undo_redo->add_do_method(this, "set_selected_index", new_selected_index);
	undo_redo->add_undo_method(*curve, "add_point", old_pos, p.left_tangent, p.right_tangent, p.left_mode, p.right_mode);
	undo_redo->add_undo_method(this, "set_selected_index", selected_index);
	undo_redo->commit_action();
}

void CurveEdit::set_point_position(int p_index, Vector2 p_pos) {
	ERR_FAIL_COND(curve.is_null());
	ERR_FAIL_INDEX_MSG(p_index, curve->get_point_count(), "Curve point is out of bounds.");

	if (initial_grab_pos == p_pos) {
		return;
	}

	// Pretend the point started from its old place.
	curve->set_point_value(p_index, initial_grab_pos.y);
	curve->set_point_offset(p_index, initial_grab_pos.x);
	// Note: Changing the offset may modify the order.
	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
	undo_redo->create_action(TTR("Modify Curve Point"));
	undo_redo->add_do_method(*curve, "set_point_value", initial_grab_index, p_pos.y);
	undo_redo->add_do_method(*curve, "set_point_offset", initial_grab_index, p_pos.x);
	undo_redo->add_do_method(this, "set_selected_index", p_index);
	undo_redo->add_undo_method(*curve, "set_point_value", p_index, initial_grab_pos.y);
	undo_redo->add_undo_method(*curve, "set_point_offset", p_index, initial_grab_pos.x);
	undo_redo->add_undo_method(this, "set_selected_index", initial_grab_index);
	undo_redo->commit_action();
}

void CurveEdit::set_point_tangents(int p_index, float p_left, float p_right) {
	ERR_FAIL_COND(curve.is_null());
	ERR_FAIL_INDEX_MSG(p_index, curve->get_point_count(), "Curve point is out of bounds.");

	if (initial_grab_left_tangent == p_left) {
		set_point_right_tangent(p_index, p_right);
		return;
	} else if (initial_grab_right_tangent == p_right) {
		set_point_left_tangent(p_index, p_left);
		return;
	}

	curve->set_point_left_tangent(p_index, initial_grab_left_tangent);
	curve->set_point_right_tangent(p_index, initial_grab_right_tangent);
	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
	undo_redo->create_action(TTR("Modify Curve Point's Tangents"));
	undo_redo->add_do_method(*curve, "set_point_left_tangent", p_index, p_left);
	undo_redo->add_do_method(*curve, "set_point_right_tangent", p_index, p_right);
	undo_redo->add_do_method(this, "set_selected_index", p_index);
	undo_redo->add_undo_method(*curve, "set_point_left_tangent", p_index, initial_grab_left_tangent);
	undo_redo->add_undo_method(*curve, "set_point_right_tangent", p_index, initial_grab_right_tangent);
	undo_redo->add_undo_method(this, "set_selected_index", p_index);
	undo_redo->commit_action();
}

void CurveEdit::set_point_left_tangent(int p_index, float p_tangent) {
	ERR_FAIL_COND(curve.is_null());
	ERR_FAIL_INDEX_MSG(p_index, curve->get_point_count(), "Curve point is out of bounds.");

	if (initial_grab_left_tangent == p_tangent) {
		return;
	}

	curve->set_point_left_tangent(p_index, initial_grab_left_tangent);
	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
	undo_redo->create_action(TTR("Modify Curve Point's Left Tangent"));
	undo_redo->add_do_method(*curve, "set_point_left_tangent", p_index, p_tangent);
	undo_redo->add_do_method(this, "set_selected_index", p_index);
	undo_redo->add_undo_method(*curve, "set_point_left_tangent", p_index, initial_grab_left_tangent);
	undo_redo->add_undo_method(this, "set_selected_index", p_index);
	undo_redo->commit_action();
}

void CurveEdit::set_point_right_tangent(int p_index, float p_tangent) {
	ERR_FAIL_COND(curve.is_null());
	ERR_FAIL_INDEX_MSG(p_index, curve->get_point_count(), "Curve point is out of bounds.");

	if (initial_grab_right_tangent == p_tangent) {
		return;
	}

	curve->set_point_right_tangent(p_index, initial_grab_right_tangent);
	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
	undo_redo->create_action(TTR("Modify Curve Point's Right Tangent"));
	undo_redo->add_do_method(*curve, "set_point_right_tangent", p_index, p_tangent);
	undo_redo->add_do_method(this, "set_selected_index", p_index);
	undo_redo->add_undo_method(*curve, "set_point_right_tangent", p_index, initial_grab_right_tangent);
	undo_redo->add_undo_method(this, "set_selected_index", p_index);
	undo_redo->commit_action();
}

void CurveEdit::toggle_linear(int p_index, TangentIndex p_tangent) {
	ERR_FAIL_COND(curve.is_null());
	ERR_FAIL_INDEX_MSG(p_index, curve->get_point_count(), "Curve point is out of bounds.");

	if (p_tangent == TANGENT_NONE) {
		return;
	}

	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
	undo_redo->create_action(TTR("Toggle Linear Curve Point's Tangent"));

	Curve::TangentMode prev_mode = (p_tangent == TANGENT_LEFT) ? curve->get_point_left_mode(p_index) : curve->get_point_right_mode(p_index);
	Curve::TangentMode mode = (prev_mode == Curve::TANGENT_LINEAR) ? Curve::TANGENT_FREE : Curve::TANGENT_LINEAR;
	float prev_angle = (p_tangent == TANGENT_LEFT) ? curve->get_point_left_tangent(p_index) : curve->get_point_right_tangent(p_index);

	// Add different methods in the UndoRedo based on the tangent passed.
	if (p_tangent == TANGENT_LEFT) {
		undo_redo->add_do_method(*curve, "set_point_left_mode", p_index, mode);
		undo_redo->add_undo_method(*curve, "set_point_left_mode", p_index, prev_mode);
		undo_redo->add_undo_method(*curve, "set_point_left_tangent", p_index, prev_angle);
	} else {
		undo_redo->add_do_method(*curve, "set_point_right_mode", p_index, mode);
		undo_redo->add_undo_method(*curve, "set_point_right_mode", p_index, prev_mode);
		undo_redo->add_undo_method(*curve, "set_point_right_tangent", p_index, prev_angle);
	}

	undo_redo->commit_action();
}

void CurveEdit::set_selected_index(int p_index) {
	if (p_index != selected_index) {
		selected_index = p_index;
		queue_redraw();
	}
}

void CurveEdit::update_view_transform() {
	Ref<Font> font = get_theme_font(SNAME("font"), SNAME("Label"));
	int font_size = get_theme_font_size(SNAME("font_size"), SNAME("Label"));

	const real_t margin = font->get_height(font_size) + 2 * EDSCALE;

	float min_y = curve.is_valid() ? curve->get_min_value() : 0.0;
	float max_y = curve.is_valid() ? curve->get_max_value() : 1.0;

	const Rect2 world_rect = Rect2(Curve::MIN_X, min_y, Curve::MAX_X, max_y - min_y);
	const Size2 view_margin(margin, margin);
	const Size2 view_size = get_size() - view_margin * 2;
	const Vector2 scale = view_size / world_rect.size;

	Transform2D world_trans;
	world_trans.translate_local(-world_rect.position - Vector2(0, world_rect.size.y));
	world_trans.scale(Vector2(scale.x, -scale.y));

	Transform2D view_trans;
	view_trans.translate_local(view_margin);

	_world_to_view = view_trans * world_trans;
}

Vector2 CurveEdit::get_tangent_view_pos(int p_index, TangentIndex p_tangent) const {
	Vector2 dir;
	if (p_tangent == TANGENT_LEFT) {
		dir = -Vector2(1, curve->get_point_left_tangent(p_index));
	} else {
		dir = Vector2(1, curve->get_point_right_tangent(p_index));
	}

	Vector2 point_pos = curve->get_point_position(p_index);
	Vector2 point_view_pos = get_view_pos(point_pos);
	Vector2 control_view_pos = get_view_pos(point_pos + dir);

	Vector2 distance_from_point = tangent_length * (control_view_pos - point_view_pos).normalized();
	Vector2 tangent_view_pos = point_view_pos + distance_from_point;

	// Since the tangent is long, it might slip outside of the area of the editor for points close to the domain/range boundaries.
	// The code below shrinks the tangent control by up to 50% so it always stays inside the editor for points within the bounds.
	float fraction_inside = 1.0;
	if (distance_from_point.x != 0.0) {
		fraction_inside = MIN(fraction_inside, ((distance_from_point.x > 0 ? get_rect().size.x : 0) - point_view_pos.x) / distance_from_point.x);
	}
	if (distance_from_point.y != 0.0) {
		fraction_inside = MIN(fraction_inside, ((distance_from_point.y > 0 ? get_rect().size.y : 0) - point_view_pos.y) / distance_from_point.y);
	}

	if (fraction_inside < 1.0 && fraction_inside > 0.5) {
		tangent_view_pos = point_view_pos + distance_from_point * fraction_inside;
	}

	return tangent_view_pos;
}

Vector2 CurveEdit::get_view_pos(Vector2 p_world_pos) const {
	return _world_to_view.xform(p_world_pos);
}

Vector2 CurveEdit::get_world_pos(Vector2 p_view_pos) const {
	return _world_to_view.affine_inverse().xform(p_view_pos);
}

// Uses non-baked points, but takes advantage of ordered iteration to be faster.
template <typename T>
static void plot_curve_accurate(const Curve &curve, float step, Vector2 scaling, T plot_func) {
	if (curve.get_point_count() <= 1) {
		// Not enough points to make a curve, so it's just a straight line.
		// The added tiny vectors make the drawn line stay exactly within the bounds in practice.
		float y = curve.sample(0);
		plot_func(Vector2(0, y) * scaling + Vector2(0.5, 0), Vector2(1.f, y) * scaling - Vector2(1.5, 0), true);

	} else {
		Vector2 first_point = curve.get_point_position(0);
		Vector2 last_point = curve.get_point_position(curve.get_point_count() - 1);

		// Edge lines
		plot_func(Vector2(0, first_point.y) * scaling + Vector2(0.5, 0), first_point * scaling, false);
		plot_func(Vector2(Curve::MAX_X, last_point.y) * scaling - Vector2(1.5, 0), last_point * scaling, false);

		// Draw section by section, so that we get maximum precision near points.
		// It's an accurate representation, but slower than using the baked one.
		for (int i = 1; i < curve.get_point_count(); ++i) {
			Vector2 a = curve.get_point_position(i - 1);
			Vector2 b = curve.get_point_position(i);

			Vector2 pos = a;
			Vector2 prev_pos = a;

			float scaled_step = step / scaling.x;
			float samples = (b.x - a.x) / scaled_step;

			for (int j = 1; j < samples; j++) {
				float x = j * scaled_step;
				pos.x = a.x + x;
				pos.y = curve.sample_local_nocheck(i - 1, x);
				plot_func(prev_pos * scaling, pos * scaling, true);
				prev_pos = pos;
			}

			plot_func(prev_pos * scaling, b * scaling, true);
		}
	}
}

struct CanvasItemPlotCurve {
	CanvasItem &ci;
	Color color1;
	Color color2;

	CanvasItemPlotCurve(CanvasItem &p_ci, Color p_color1, Color p_color2) :
			ci(p_ci),
			color1(p_color1),
			color2(p_color2) {}

	void operator()(Vector2 pos0, Vector2 pos1, bool in_definition) {
		ci.draw_line(pos0, pos1, in_definition ? color1 : color2, 0.5, true);
	}
};

void CurveEdit::_redraw() {
	if (curve.is_null()) {
		return;
	}

	update_view_transform();

	// Draw background.

	Vector2 view_size = get_rect().size;
	draw_style_box(get_theme_stylebox(SNAME("panel"), SNAME("Tree")), Rect2(Point2(), view_size));

	// Draw snapping grid, then primary grid.
	draw_set_transform_matrix(_world_to_view);

	Vector2 min_edge = get_world_pos(Vector2(0, view_size.y));
	Vector2 max_edge = get_world_pos(Vector2(view_size.x, 0));

	const Color grid_color_primary = get_theme_color(SNAME("mono_color"), EditorStringName(Editor)) * Color(1, 1, 1, 0.25);
	const Color grid_color = get_theme_color(SNAME("mono_color"), EditorStringName(Editor)) * Color(1, 1, 1, 0.1);

	const Vector2i grid_steps = Vector2i(4, 2);
	const Vector2 step_size = Vector2(1, curve->get_range()) / grid_steps;

	draw_line(Vector2(min_edge.x, curve->get_min_value()), Vector2(max_edge.x, curve->get_min_value()), grid_color_primary);
	draw_line(Vector2(max_edge.x, curve->get_max_value()), Vector2(min_edge.x, curve->get_max_value()), grid_color_primary);
	draw_line(Vector2(0, min_edge.y), Vector2(0, max_edge.y), grid_color_primary);
	draw_line(Vector2(1, max_edge.y), Vector2(1, min_edge.y), grid_color_primary);

	for (int i = 1; i < grid_steps.x; i++) {
		real_t x = i * step_size.x;
		draw_line(Vector2(x, min_edge.y), Vector2(x, max_edge.y), grid_color);
	}

	for (int i = 1; i < grid_steps.y; i++) {
		real_t y = curve->get_min_value() + i * step_size.y;
		draw_line(Vector2(min_edge.x, y), Vector2(max_edge.x, y), grid_color);
	}

	// Draw number markings.
	draw_set_transform_matrix(Transform2D());

	Ref<Font> font = get_theme_font(SNAME("font"), SNAME("Label"));
	int font_size = get_theme_font_size(SNAME("font_size"), SNAME("Label"));
	float font_height = font->get_height(font_size);
	Color text_color = get_theme_color(SNAME("font_color"), EditorStringName(Editor));

	for (int i = 0; i <= grid_steps.x; ++i) {
		real_t x = i * step_size.x;
		draw_string(font, get_view_pos(Vector2(x - step_size.x / 2, curve->get_min_value())) + Vector2(0, font_height - Math::round(2 * EDSCALE)), String::num(x, 2), HORIZONTAL_ALIGNMENT_CENTER, get_view_pos(Vector2(step_size.x, 0)).x, font_size, text_color);
	}

	for (int i = 0; i <= grid_steps.y; ++i) {
		real_t y = curve->get_min_value() + i * step_size.y;
		draw_string(font, get_view_pos(Vector2(0, y)) + Vector2(2, -2), String::num(y, 2), HORIZONTAL_ALIGNMENT_LEFT, -1, font_size, text_color);
	}

	// Draw curve.

	// An unusual transform so we can offset the curve before scaling it up, allowing the curve to be antialiased.
	// The scaling up ensures that the curve rendering doesn't break when we use a quad line to draw it.
	draw_set_transform_matrix(Transform2D(0, get_view_pos(Vector2(0, 0))));

	const Color line_color = get_theme_color(SNAME("font_color"), EditorStringName(Editor));
	const Color edge_line_color = get_theme_color(SNAME("font_color"), EditorStringName(Editor)) * Color(1, 1, 1, 0.75);

	CanvasItemPlotCurve plot_func(*this, line_color, edge_line_color);
	plot_curve_accurate(**curve, 2.f, (get_view_pos(Vector2(1, curve->get_max_value())) - get_view_pos(Vector2(0, curve->get_min_value()))) / Vector2(1, curve->get_range()), plot_func);

	// Draw points, except for the selected one.
	draw_set_transform_matrix(Transform2D());

	bool shift_pressed = Input::get_singleton()->is_key_pressed(Key::SHIFT);

	const Color point_color = get_theme_color(SNAME("font_color"), EditorStringName(Editor));

	for (int i = 0; i < curve->get_point_count(); ++i) {
		Vector2 pos = get_view_pos(curve->get_point_position(i));
		if (selected_index != i) {
			draw_rect(Rect2(pos, Vector2(0, 0)).grow(point_radius), point_color);
		}
		if (hovered_index == i && hovered_tangent_index == TANGENT_NONE) {
			draw_rect(Rect2(pos, Vector2(0, 0)).grow(hover_radius - Math::round(3 * EDSCALE)), line_color, false, Math::round(1 * EDSCALE));
		}
	}

	// Draw selected point and its tangents.

	if (selected_index >= 0) {
		const Vector2 point_pos = curve->get_point_position(selected_index);
		const Color selected_point_color = get_theme_color(SNAME("accent_color"), EditorStringName(Editor));

		// Draw tangents if not dragging a point, or if holding a point without having moved it yet.
		if (grabbing == GRAB_NONE || initial_grab_pos == point_pos || selected_tangent_index != TANGENT_NONE) {
			const Color selected_tangent_color = get_theme_color(SNAME("accent_color"), EditorStringName(Editor)).darkened(0.25);
			const Color tangent_color = get_theme_color(SNAME("font_color"), EditorStringName(Editor)).darkened(0.25);

			if (selected_index != 0) {
				Vector2 control_pos = get_tangent_view_pos(selected_index, TANGENT_LEFT);
				Color left_tangent_color = (selected_tangent_index == TANGENT_LEFT) ? selected_tangent_color : tangent_color;

				draw_line(get_view_pos(point_pos), control_pos, left_tangent_color, 0.5 * EDSCALE, true);
				// Square for linear mode, circle otherwise.
				if (curve->get_point_left_mode(selected_index) == Curve::TANGENT_FREE) {
					draw_circle(control_pos, tangent_radius, left_tangent_color);
				} else {
					draw_rect(Rect2(control_pos, Vector2(0, 0)).grow(tangent_radius), left_tangent_color);
				}
				// Hover indicator.
				if (hovered_tangent_index == TANGENT_LEFT || (hovered_tangent_index == TANGENT_RIGHT && !shift_pressed && curve->get_point_left_mode(selected_index) != Curve::TANGENT_LINEAR)) {
					draw_rect(Rect2(control_pos, Vector2(0, 0)).grow(tangent_hover_radius - Math::round(3 * EDSCALE)), tangent_color, false, Math::round(1 * EDSCALE));
				}
			}

			if (selected_index != curve->get_point_count() - 1) {
				Vector2 control_pos = get_tangent_view_pos(selected_index, TANGENT_RIGHT);
				Color right_tangent_color = (selected_tangent_index == TANGENT_RIGHT) ? selected_tangent_color : tangent_color;

				draw_line(get_view_pos(point_pos), control_pos, right_tangent_color, 0.5 * EDSCALE, true);
				// Square for linear mode, circle otherwise.
				if (curve->get_point_right_mode(selected_index) == Curve::TANGENT_FREE) {
					draw_circle(control_pos, tangent_radius, right_tangent_color);
				} else {
					draw_rect(Rect2(control_pos, Vector2(0, 0)).grow(tangent_radius), right_tangent_color);
				}
				// Hover indicator.
				if (hovered_tangent_index == TANGENT_RIGHT || (hovered_tangent_index == TANGENT_LEFT && !shift_pressed && curve->get_point_right_mode(selected_index) != Curve::TANGENT_LINEAR)) {
					draw_rect(Rect2(control_pos, Vector2(0, 0)).grow(tangent_hover_radius - Math::round(3 * EDSCALE)), tangent_color, false, Math::round(1 * EDSCALE));
				}
			}
		}

		draw_rect(Rect2(get_view_pos(point_pos), Vector2(0, 0)).grow(point_radius), selected_point_color);
	}

	// Draw help text.

	if (selected_index > 0 && selected_index < curve->get_point_count() - 1 && selected_tangent_index == TANGENT_NONE && hovered_tangent_index != TANGENT_NONE && !shift_pressed) {
		float width = view_size.x - 50 * EDSCALE;
		text_color.a *= 0.4;

		draw_multiline_string(font, Vector2(25 * EDSCALE, font_height - Math::round(2 * EDSCALE)), TTR("Hold Shift to edit tangents individually"), HORIZONTAL_ALIGNMENT_CENTER, width, font_size, -1, text_color);

	} else if (selected_index != -1 && selected_tangent_index == TANGENT_NONE) {
		const Vector2 point_pos = curve->get_point_position(selected_index);
		float width = view_size.x - 50 * EDSCALE;
		text_color.a *= 0.8;

		draw_string(font, Vector2(25 * EDSCALE, font_height - Math::round(2 * EDSCALE)), vformat("(%.2f, %.2f)", point_pos.x, point_pos.y), HORIZONTAL_ALIGNMENT_CENTER, width, font_size, text_color);

	} else if (selected_index != -1 && selected_tangent_index != TANGENT_NONE) {
		float width = view_size.x - 50 * EDSCALE;
		text_color.a *= 0.8;
		real_t theta = Math::rad_to_deg(Math::atan(selected_tangent_index == TANGENT_LEFT ? -1 * curve->get_point_left_tangent(selected_index) : curve->get_point_right_tangent(selected_index)));

		draw_string(font, Vector2(25 * EDSCALE, font_height - Math::round(2 * EDSCALE)), String::num(theta, 1) + String::utf8(" °"), HORIZONTAL_ALIGNMENT_CENTER, width, font_size, text_color);
	}

	// Draw temporary constraints and snapping axes.
	draw_set_transform_matrix(_world_to_view);

	if (Input::get_singleton()->is_key_pressed(Key::ALT) && grabbing != GRAB_NONE && selected_tangent_index == TANGENT_NONE) {
		float prev_point_offset = (selected_index > 0) ? curve->get_point_position(selected_index - 1).x : 0.0;
		float next_point_offset = (selected_index < curve->get_point_count() - 1) ? curve->get_point_position(selected_index + 1).x : 1.0;

		draw_line(Vector2(prev_point_offset, curve->get_min_value()), Vector2(prev_point_offset, curve->get_max_value()), Color(point_color, 0.6));
		draw_line(Vector2(next_point_offset, curve->get_min_value()), Vector2(next_point_offset, curve->get_max_value()), Color(point_color, 0.6));
	}

	if (shift_pressed && grabbing != GRAB_NONE && selected_tangent_index == TANGENT_NONE) {
		draw_line(Vector2(initial_grab_pos.x, curve->get_min_value()), Vector2(initial_grab_pos.x, curve->get_max_value()), get_theme_color(SNAME("axis_x_color"), EditorStringName(Editor)).darkened(0.4));
		draw_line(Vector2(0, initial_grab_pos.y), Vector2(1, initial_grab_pos.y), get_theme_color(SNAME("axis_y_color"), EditorStringName(Editor)).darkened(0.4));
	}
}

///////////////////////

const int CurveEditor::DEFAULT_SNAP = 10;

void CurveEditor::_set_snap_enabled(bool p_enabled) {
	curve_editor_rect->set_snap_enabled(p_enabled);
	snap_count_edit->set_visible(p_enabled);
}

void CurveEditor::_set_snap_count(int p_snap_count) {
	curve_editor_rect->set_snap_count(CLAMP(p_snap_count, 2, 100));
}

void CurveEditor::_on_preset_item_selected(int p_preset_id) {
	curve_editor_rect->use_preset(p_preset_id);
}

void CurveEditor::set_curve(const Ref<Curve> &p_curve) {
	curve_editor_rect->set_curve(p_curve);
}

void CurveEditor::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_THEME_CHANGED: {
			spacing = Math::round(BASE_SPACING * get_theme_default_base_scale());
			snap_button->set_icon(get_editor_theme_icon(SNAME("SnapGrid")));
			PopupMenu *p = presets_button->get_popup();
			p->clear();
			p->add_icon_item(get_editor_theme_icon(SNAME("CurveConstant")), TTR("Constant"), CurveEdit::PRESET_CONSTANT);
			p->add_icon_item(get_editor_theme_icon(SNAME("CurveLinear")), TTR("Linear"), CurveEdit::PRESET_LINEAR);
			p->add_icon_item(get_editor_theme_icon(SNAME("CurveIn")), TTR("Ease In"), CurveEdit::PRESET_EASE_IN);
			p->add_icon_item(get_editor_theme_icon(SNAME("CurveOut")), TTR("Ease Out"), CurveEdit::PRESET_EASE_OUT);
			p->add_icon_item(get_editor_theme_icon(SNAME("CurveInOut")), TTR("Smoothstep"), CurveEdit::PRESET_SMOOTHSTEP);
		} break;
		case NOTIFICATION_READY: {
			Ref<Curve> curve = curve_editor_rect->get_curve();
			if (curve.is_valid()) {
				// Set snapping settings based on the curve's meta.
				snap_button->set_pressed(curve->get_meta("_snap_enabled", false));
				snap_count_edit->set_value(curve->get_meta("_snap_count", DEFAULT_SNAP));
			}
		} break;
		case NOTIFICATION_RESIZED:
			curve_editor_rect->update_minimum_size();
			break;
	}
}

CurveEditor::CurveEditor() {
	HFlowContainer *toolbar = memnew(HFlowContainer);
	add_child(toolbar);

	snap_button = memnew(Button);
	snap_button->set_tooltip_text(TTR("Toggle Grid Snap"));
	snap_button->set_toggle_mode(true);
	toolbar->add_child(snap_button);
	snap_button->connect("toggled", callable_mp(this, &CurveEditor::_set_snap_enabled));

	toolbar->add_child(memnew(VSeparator));

	snap_count_edit = memnew(EditorSpinSlider);
	snap_count_edit->set_min(2);
	snap_count_edit->set_max(100);
	snap_count_edit->set_value(DEFAULT_SNAP);
	snap_count_edit->set_custom_minimum_size(Size2(65 * EDSCALE, 0));
	toolbar->add_child(snap_count_edit);
	snap_count_edit->connect("value_changed", callable_mp(this, &CurveEditor::_set_snap_count));

	presets_button = memnew(MenuButton);
	presets_button->set_text(TTR("Presets"));
	presets_button->set_switch_on_hover(true);
	presets_button->set_h_size_flags(SIZE_EXPAND | SIZE_SHRINK_END);
	toolbar->add_child(presets_button);
	presets_button->get_popup()->connect("id_pressed", callable_mp(this, &CurveEditor::_on_preset_item_selected));

	curve_editor_rect = memnew(CurveEdit);
	add_child(curve_editor_rect);

	// Some empty space below. Not a part of the curve editor so it can't draw in it.
	Control *empty_space = memnew(Control);
	empty_space->set_custom_minimum_size(Vector2(0, spacing));
	add_child(empty_space);

	set_mouse_filter(MOUSE_FILTER_STOP);
	_set_snap_enabled(snap_button->is_pressed());
	_set_snap_count(snap_count_edit->get_value());
}

///////////////////////

bool EditorInspectorPluginCurve::can_handle(Object *p_object) {
	return Object::cast_to<Curve>(p_object) != nullptr;
}

void EditorInspectorPluginCurve::parse_begin(Object *p_object) {
	Curve *curve = Object::cast_to<Curve>(p_object);
	ERR_FAIL_NULL(curve);
	Ref<Curve> c(curve);

	CurveEditor *editor = memnew(CurveEditor);
	editor->set_curve(c);
	add_custom_control(editor);
}

CurveEditorPlugin::CurveEditorPlugin() {
	Ref<EditorInspectorPluginCurve> plugin;
	plugin.instantiate();
	add_inspector_plugin(plugin);

	EditorInterface::get_singleton()->get_resource_previewer()->add_preview_generator(memnew(CurvePreviewGenerator));
}

///////////////////////

bool CurvePreviewGenerator::handles(const String &p_type) const {
	return p_type == "Curve";
}

Ref<Texture2D> CurvePreviewGenerator::generate(const Ref<Resource> &p_from, const Size2 &p_size, Dictionary &p_metadata) const {
	Ref<Curve> curve = p_from;
	if (curve.is_null()) {
		return Ref<Texture2D>();
	}

	Size2 thumbnail_size = p_size * EDSCALE;
	Ref<Image> img_ref;
	img_ref.instantiate();
	Image &im = **img_ref;
	im.initialize_data(thumbnail_size.x, thumbnail_size.y, false, Image::FORMAT_RGBA8);

	Color bg_color(0.1, 0.1, 0.1, 1.0);
	Color line_color(0.8, 0.8, 0.8, 1.0);

	im.fill(bg_color);
	// Set the first pixel of the thumbnail.
	float v = (curve->sample_baked(0) - curve->get_min_value()) / curve->get_range();
	int y = CLAMP(im.get_height() - v * im.get_height(), 0, im.get_height() - 1);
	im.set_pixel(0, y, line_color);

	// Plot a line towards the next point.
	int prev_y = y;
	for (int x = 1; x < im.get_width(); ++x) {
		float t = static_cast<float>(x) / im.get_width();
		v = (curve->sample_baked(t) - curve->get_min_value()) / curve->get_range();
		y = CLAMP(im.get_height() - v * im.get_height(), 0, im.get_height() - 1);

		Vector<Point2i> points = Geometry2D::bresenham_line(Point2i(x - 1, prev_y), Point2i(x, y));
		for (Point2i point : points) {
			im.set_pixelv(point, line_color);
		}
		prev_y = y;
	}

	return ImageTexture::create_from_image(img_ref);
}