/*************************************************************************/
/*  cpu_particles_2d.h                                                   */
/*************************************************************************/
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#ifndef CPU_PARTICLES_2D_H
#define CPU_PARTICLES_2D_H

#include "core/templates/rid.h"
#include "scene/2d/node_2d.h"
#include "scene/resources/texture.h"

class CPUParticles2D : public Node2D {
private:
	GDCLASS(CPUParticles2D, Node2D);

public:
	enum DrawOrder {
		DRAW_ORDER_INDEX,
		DRAW_ORDER_LIFETIME,
	};

	enum Parameter {
		PARAM_INITIAL_LINEAR_VELOCITY,
		PARAM_ANGULAR_VELOCITY,
		PARAM_ORBIT_VELOCITY,
		PARAM_LINEAR_ACCEL,
		PARAM_RADIAL_ACCEL,
		PARAM_TANGENTIAL_ACCEL,
		PARAM_DAMPING,
		PARAM_ANGLE,
		PARAM_SCALE,
		PARAM_HUE_VARIATION,
		PARAM_ANIM_SPEED,
		PARAM_ANIM_OFFSET,
		PARAM_MAX
	};

	enum ParticleFlags {
		PARTICLE_FLAG_ALIGN_Y_TO_VELOCITY,
		PARTICLE_FLAG_ROTATE_Y, // Unused, but exposed for consistency with 3D.
		PARTICLE_FLAG_DISABLE_Z, // Unused, but exposed for consistency with 3D.
		PARTICLE_FLAG_MAX
	};

	enum EmissionShape {
		EMISSION_SHAPE_POINT,
		EMISSION_SHAPE_SPHERE,
		EMISSION_SHAPE_RECTANGLE,
		EMISSION_SHAPE_POINTS,
		EMISSION_SHAPE_DIRECTED_POINTS,
		EMISSION_SHAPE_MAX
	};

private:
	bool emitting = false;

	struct Particle {
		Transform2D transform;
		Color color;
		float custom[4] = {};
		real_t rotation = 0.0;
		Vector2 velocity;
		bool active = false;
		real_t angle_rand = 0.0;
		real_t scale_rand = 0.0;
		real_t hue_rot_rand = 0.0;
		real_t anim_offset_rand = 0.0;
		float time = 0.0;
		float lifetime = 0.0;
		Color base_color;

		uint32_t seed = 0;
	};

	float time = 0.0;
	float inactive_time = 0.0;
	float frame_remainder = 0.0;
	int cycle = 0;
	bool redraw = false;

	RID mesh;
	RID multimesh;

	Vector<Particle> particles;
	Vector<float> particle_data;
	Vector<int> particle_order;

	struct SortLifetime {
		const Particle *particles = nullptr;

		bool operator()(int p_a, int p_b) const {
			return particles[p_a].time > particles[p_b].time;
		}
	};

	struct SortAxis {
		const Particle *particles = nullptr;
		Vector2 axis;
		bool operator()(int p_a, int p_b) const {
			return axis.dot(particles[p_a].transform[2]) < axis.dot(particles[p_b].transform[2]);
		}
	};

	//

	bool one_shot = false;

	float lifetime = 1.0;
	float pre_process_time = 0.0;
	real_t explosiveness_ratio = 0.0;
	real_t randomness_ratio = 0.0;
	real_t lifetime_randomness = 0.0;
	real_t speed_scale = 1.0;
	bool local_coords;
	int fixed_fps = 0;
	bool fractional_delta = true;

	Transform2D inv_emission_transform;

	DrawOrder draw_order = DRAW_ORDER_INDEX;

	Ref<Texture2D> texture;

	////////

	Vector2 direction = Vector2(1, 0);
	real_t spread = 45.0;

	real_t parameters[PARAM_MAX];
	real_t randomness[PARAM_MAX];

	Ref<Curve> curve_parameters[PARAM_MAX];
	Color color;
	Ref<Gradient> color_ramp;

	bool particle_flags[PARTICLE_FLAG_MAX];

	EmissionShape emission_shape = EMISSION_SHAPE_POINT;
	real_t emission_sphere_radius = 1.0;
	Vector2 emission_rect_extents = Vector2(1, 1);
	Vector<Vector2> emission_points;
	Vector<Vector2> emission_normals;
	Vector<Color> emission_colors;
	int emission_point_count = 0;

	Vector2 gravity = Vector2(0, 98);

	void _update_internal();
	void _particles_process(float p_delta);
	void _update_particle_data_buffer();

	Mutex update_mutex;

	void _update_render_thread();

	void _update_mesh_texture();

	void _set_redraw(bool p_redraw);

	void _texture_changed();

protected:
	static void _bind_methods();
	void _notification(int p_what);
	virtual void _validate_property(PropertyInfo &property) const override;

public:
	void set_emitting(bool p_emitting);
	void set_amount(int p_amount);
	void set_lifetime(float p_lifetime);
	void set_one_shot(bool p_one_shot);
	void set_pre_process_time(float p_time);
	void set_explosiveness_ratio(real_t p_ratio);
	void set_randomness_ratio(real_t p_ratio);
	void set_lifetime_randomness(float p_random);
	void set_visibility_aabb(const Rect2 &p_aabb);
	void set_use_local_coordinates(bool p_enable);
	void set_speed_scale(real_t p_scale);

	bool is_emitting() const;
	int get_amount() const;
	float get_lifetime() const;
	bool get_one_shot() const;
	float get_pre_process_time() const;
	real_t get_explosiveness_ratio() const;
	real_t get_randomness_ratio() const;
	float get_lifetime_randomness() const;
	Rect2 get_visibility_aabb() const;
	bool get_use_local_coordinates() const;
	real_t get_speed_scale() const;

	void set_fixed_fps(int p_count);
	int get_fixed_fps() const;

	void set_fractional_delta(bool p_enable);
	bool get_fractional_delta() const;

	void set_draw_order(DrawOrder p_order);
	DrawOrder get_draw_order() const;

	void set_draw_passes(int p_count);
	int get_draw_passes() const;

	void set_texture(const Ref<Texture2D> &p_texture);
	Ref<Texture2D> get_texture() const;

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

	void set_direction(Vector2 p_direction);
	Vector2 get_direction() const;

	void set_spread(real_t p_spread);
	real_t get_spread() const;

	void set_param(Parameter p_param, real_t p_value);
	real_t get_param(Parameter p_param) const;

	void set_param_randomness(Parameter p_param, real_t p_value);
	real_t get_param_randomness(Parameter p_param) const;

	void set_param_curve(Parameter p_param, const Ref<Curve> &p_curve);
	Ref<Curve> get_param_curve(Parameter p_param) const;

	void set_color(const Color &p_color);
	Color get_color() const;

	void set_color_ramp(const Ref<Gradient> &p_ramp);
	Ref<Gradient> get_color_ramp() const;

	void set_particle_flag(ParticleFlags p_particle_flag, bool p_enable);
	bool get_particle_flag(ParticleFlags p_particle_flag) const;

	void set_emission_shape(EmissionShape p_shape);
	void set_emission_sphere_radius(real_t p_radius);
	void set_emission_rect_extents(Vector2 p_extents);
	void set_emission_points(const Vector<Vector2> &p_points);
	void set_emission_normals(const Vector<Vector2> &p_normals);
	void set_emission_colors(const Vector<Color> &p_colors);
	void set_emission_point_count(int p_count);

	EmissionShape get_emission_shape() const;
	real_t get_emission_sphere_radius() const;
	Vector2 get_emission_rect_extents() const;
	Vector<Vector2> get_emission_points() const;
	Vector<Vector2> get_emission_normals() const;
	Vector<Color> get_emission_colors() const;
	int get_emission_point_count() const;

	void set_gravity(const Vector2 &p_gravity);
	Vector2 get_gravity() const;

	virtual String get_configuration_warning() const override;

	void restart();

	void convert_from_particles(Node *p_particles);

	CPUParticles2D();
	~CPUParticles2D();
};

VARIANT_ENUM_CAST(CPUParticles2D::DrawOrder)
VARIANT_ENUM_CAST(CPUParticles2D::Parameter)
VARIANT_ENUM_CAST(CPUParticles2D::ParticleFlags)
VARIANT_ENUM_CAST(CPUParticles2D::EmissionShape)

#endif // CPU_PARTICLES_2D_H