/*************************************************************************/
/*  spring_arm.cpp                                                       */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
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#include "spring_arm.h"
#include "core/config/engine.h"
#include "scene/3d/collision_object.h"
#include "scene/resources/shape.h"
#include "scene/resources/sphere_shape.h"
#include "scene/resources/world.h"
#include "servers/physics_server.h"

SpringArm::SpringArm() :
		spring_length(1),
		current_spring_length(0),
		keep_child_basis(false),
		mask(1),
		margin(0.01) {}

void SpringArm::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_ENTER_TREE:
			if (!Engine::get_singleton()->is_editor_hint()) {
				set_physics_process_internal(true);
			}
			break;
		case NOTIFICATION_EXIT_TREE:
			if (!Engine::get_singleton()->is_editor_hint()) {
				set_physics_process_internal(false);
			}
			break;
		case NOTIFICATION_INTERNAL_PHYSICS_PROCESS:
			process_spring();
			break;
	}
}

void SpringArm::_bind_methods() {
	ClassDB::bind_method(D_METHOD("get_hit_length"), &SpringArm::get_hit_length);

	ClassDB::bind_method(D_METHOD("set_length", "length"), &SpringArm::set_length);
	ClassDB::bind_method(D_METHOD("get_length"), &SpringArm::get_length);

	ClassDB::bind_method(D_METHOD("set_shape", "shape"), &SpringArm::set_shape);
	ClassDB::bind_method(D_METHOD("get_shape"), &SpringArm::get_shape);

	ClassDB::bind_method(D_METHOD("add_excluded_object", "RID"), &SpringArm::add_excluded_object);
	ClassDB::bind_method(D_METHOD("remove_excluded_object", "RID"), &SpringArm::remove_excluded_object);
	ClassDB::bind_method(D_METHOD("clear_excluded_objects"), &SpringArm::clear_excluded_objects);

	ClassDB::bind_method(D_METHOD("set_collision_mask", "mask"), &SpringArm::set_mask);
	ClassDB::bind_method(D_METHOD("get_collision_mask"), &SpringArm::get_mask);

	ClassDB::bind_method(D_METHOD("set_margin", "margin"), &SpringArm::set_margin);
	ClassDB::bind_method(D_METHOD("get_margin"), &SpringArm::get_margin);

	ADD_PROPERTY(PropertyInfo(Variant::INT, "collision_mask", PROPERTY_HINT_LAYERS_3D_PHYSICS), "set_collision_mask", "get_collision_mask");
	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "shape", PROPERTY_HINT_RESOURCE_TYPE, "Shape"), "set_shape", "get_shape");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "spring_length"), "set_length", "get_length");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "margin"), "set_margin", "get_margin");
}

float SpringArm::get_length() const {
	return spring_length;
}

void SpringArm::set_length(float p_length) {
	if (is_inside_tree() && (Engine::get_singleton()->is_editor_hint() || get_tree()->is_debugging_collisions_hint())) {
		update_gizmos();
	}

	spring_length = p_length;
}

void SpringArm::set_shape(Ref<Shape> p_shape) {
	shape = p_shape;
}

Ref<Shape> SpringArm::get_shape() const {
	return shape;
}

void SpringArm::set_mask(uint32_t p_mask) {
	mask = p_mask;
}

uint32_t SpringArm::get_mask() {
	return mask;
}

float SpringArm::get_margin() {
	return margin;
}

void SpringArm::set_margin(float p_margin) {
	margin = p_margin;
}

void SpringArm::add_excluded_object(RID p_rid) {
	excluded_objects.insert(p_rid);
}

bool SpringArm::remove_excluded_object(RID p_rid) {
	return excluded_objects.erase(p_rid);
}

void SpringArm::clear_excluded_objects() {
	excluded_objects.clear();
}

float SpringArm::get_hit_length() {
	return current_spring_length;
}

void SpringArm::process_spring() {
	// From
	real_t motion_delta(1);
	real_t motion_delta_unsafe(1);

	Vector3 motion;
	const Vector3 cast_direction(get_global_transform().basis.xform(Vector3(0, 0, 1)));

	if (shape.is_null()) {
		motion = Vector3(cast_direction * (spring_length));
		PhysicsDirectSpaceState::RayResult r;
		bool intersected = get_world()->get_direct_space_state()->intersect_ray(get_global_transform().origin, get_global_transform().origin + motion, r, excluded_objects, mask);
		if (intersected) {
			float dist = get_global_transform().origin.distance_to(r.position);
			dist -= margin;
			motion_delta = dist / (spring_length);
		}
	} else {
		motion = Vector3(cast_direction * spring_length);
		get_world()->get_direct_space_state()->cast_motion(shape->get_rid(), get_global_transform(), motion, 0, motion_delta, motion_delta_unsafe, excluded_objects, mask);
	}

	current_spring_length = spring_length * motion_delta;
	Transform childs_transform;
	childs_transform.origin = get_global_transform().origin + cast_direction * (spring_length * motion_delta);

	for (int i = get_child_count() - 1; 0 <= i; --i) {
		Spatial *child = Object::cast_to<Spatial>(get_child(i));
		if (child) {
			childs_transform.basis = child->get_global_transform().basis;
			child->set_global_transform(childs_transform);
		}
	}
}