/*************************************************************************/
/*  cpu_particles_2d.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 "cpu_particles_2d.h"
#include "core/containers/rid.h"
#include "core/core_string_names.h"
#include "core/os/os.h"
#include "core/containers/fixed_array.h"
#include "core/math/transform_interpolator.h"

#include "scene/2d/canvas_item.h"
#include "scene/resources/material/particles_material.h"
#include "scene/resources/texture.h"
#include "servers/rendering_server.h"

void CPUParticles2D::set_emitting(bool p_emitting) {
	if (emitting == p_emitting) {
		return;
	}

	emitting = p_emitting;
	if (emitting) {
		set_process_internal(true);
	}
}

void CPUParticles2D::set_amount(int p_amount) {
	ERR_FAIL_COND_MSG(p_amount < 1, "Amount of particles must be greater than 0.");

	particles.resize(p_amount);
	particles_prev.resize(p_amount);
	{
		PoolVector<Particle>::Write w = particles.write();

		// each particle must be set to false
		// zeroing the data also prevents uninitialized memory being sent to GPU
		memset(static_cast<void *>(&w[0]), 0, p_amount * sizeof(Particle));
		// cast to prevent compiler warning .. note this relies on Particle not containing any complex types.
		// an alternative is to use some zero method per item but the generated code will be far less efficient.

		for (int i = 0; i < p_amount; i++) {
			particles_prev[i].blank();
		}
	}

	particle_data.resize((8 + 4 + 1) * p_amount);
	particle_data_prev.resize(particle_data.size());

	// We must fill immediately to prevent garbage data and Nans
	// being sent to the visual server with set_as_bulk_array,
	// if this is sent before being regularly updated.
	particle_data.fill(0);
	particle_data_prev.fill(0);

	RS::get_singleton()->multimesh_allocate(multimesh, p_amount, RS::MULTIMESH_TRANSFORM_2D, RS::MULTIMESH_COLOR_8BIT, RS::MULTIMESH_CUSTOM_DATA_FLOAT);

	particle_order.resize(p_amount);
}
void CPUParticles2D::set_lifetime(float p_lifetime) {
	ERR_FAIL_COND_MSG(p_lifetime <= 0, "Particles lifetime must be greater than 0.");
	lifetime = p_lifetime;
}

void CPUParticles2D::set_one_shot(bool p_one_shot) {
	one_shot = p_one_shot;
}

void CPUParticles2D::set_pre_process_time(float p_time) {
	pre_process_time = p_time;
}
void CPUParticles2D::set_explosiveness_ratio(float p_ratio) {
	explosiveness_ratio = p_ratio;
}
void CPUParticles2D::set_randomness_ratio(float p_ratio) {
	randomness_ratio = p_ratio;
}
void CPUParticles2D::set_lifetime_randomness(float p_random) {
	lifetime_randomness = p_random;
}
void CPUParticles2D::set_use_local_coordinates(bool p_enable) {
	local_coords = p_enable;

#ifdef PANDEMONIUM_CPU_PARTICLES_2D_LEGACY_COMPATIBILITY
	// We only need NOTIFICATION_TRANSFORM_CHANGED when in global mode
	// non-interpolated for legacy particles
	// (because they are in local space and need inverse parent xform applying).
	set_notify_transform(!_interpolated && !local_coords);

	// Prevent sending item transforms when using global coords,
	// and inform VisualServer to use identity mode.
	set_canvas_item_use_identity_transform(_interpolated && !local_coords);

	// Always reset this, as it is unused when interpolation is on.
	// (i.e. We do particles in global space, rather than pseudo globalspace.)
	inv_emission_transform = Transform2D();
#else
	// When not using legacy, there is never a need for NOTIFICATION_TRANSFORM_CHANGED,
	// so we leave it at the default (false).
	set_canvas_item_use_identity_transform(!local_coords);

	// We only need NOTIFICATION_TRANSFORM_CHANGED
	// when following an interpolated target.
	set_notify_transform(_interpolation_data.interpolated_follow);
#endif
}

void CPUParticles2D::set_speed_scale(float p_scale) {
	speed_scale = p_scale;
}

bool CPUParticles2D::is_emitting() const {
	return emitting;
}
int CPUParticles2D::get_amount() const {
	return particles.size();
}
float CPUParticles2D::get_lifetime() const {
	return lifetime;
}
bool CPUParticles2D::get_one_shot() const {
	return one_shot;
}

float CPUParticles2D::get_pre_process_time() const {
	return pre_process_time;
}
float CPUParticles2D::get_explosiveness_ratio() const {
	return explosiveness_ratio;
}
float CPUParticles2D::get_randomness_ratio() const {
	return randomness_ratio;
}
float CPUParticles2D::get_lifetime_randomness() const {
	return lifetime_randomness;
}

bool CPUParticles2D::get_use_local_coordinates() const {
	return local_coords;
}

float CPUParticles2D::get_speed_scale() const {
	return speed_scale;
}

void CPUParticles2D::set_draw_order(DrawOrder p_order) {
	draw_order = p_order;
}

CPUParticles2D::DrawOrder CPUParticles2D::get_draw_order() const {
	return draw_order;
}

void CPUParticles2D::_update_mesh_texture() {
	Size2 tex_size;
	if (texture.is_valid()) {
		tex_size = texture->get_size();
	} else {
		tex_size = Size2(1, 1);
	}
	PoolVector<Vector2> vertices;
	vertices.push_back(-tex_size * 0.5);
	vertices.push_back(-tex_size * 0.5 + Vector2(tex_size.x, 0));
	vertices.push_back(-tex_size * 0.5 + Vector2(tex_size.x, tex_size.y));
	vertices.push_back(-tex_size * 0.5 + Vector2(0, tex_size.y));
	PoolVector<Vector2> uvs;
	AtlasTexture *atlas_texure = Object::cast_to<AtlasTexture>(*texture);
	if (atlas_texure && atlas_texure->get_atlas().is_valid()) {
		Rect2 region_rect = atlas_texure->get_region();
		Size2 atlas_size = atlas_texure->get_atlas()->get_size();
		uvs.push_back(Vector2(region_rect.position.x / atlas_size.x, region_rect.position.y / atlas_size.y));
		uvs.push_back(Vector2((region_rect.position.x + region_rect.size.x) / atlas_size.x, region_rect.position.y / atlas_size.y));
		uvs.push_back(Vector2((region_rect.position.x + region_rect.size.x) / atlas_size.x, (region_rect.position.y + region_rect.size.y) / atlas_size.y));
		uvs.push_back(Vector2(region_rect.position.x / atlas_size.x, (region_rect.position.y + region_rect.size.y) / atlas_size.y));
	} else {
		uvs.push_back(Vector2(0, 0));
		uvs.push_back(Vector2(1, 0));
		uvs.push_back(Vector2(1, 1));
		uvs.push_back(Vector2(0, 1));
	}
	PoolVector<Color> colors;
	colors.push_back(Color(1, 1, 1, 1));
	colors.push_back(Color(1, 1, 1, 1));
	colors.push_back(Color(1, 1, 1, 1));
	colors.push_back(Color(1, 1, 1, 1));
	PoolVector<int> indices;
	indices.push_back(0);
	indices.push_back(1);
	indices.push_back(2);
	indices.push_back(2);
	indices.push_back(3);
	indices.push_back(0);

	Array arr;
	arr.resize(RS::ARRAY_MAX);
	arr[RS::ARRAY_VERTEX] = vertices;
	arr[RS::ARRAY_TEX_UV] = uvs;
	arr[RS::ARRAY_COLOR] = colors;
	arr[RS::ARRAY_INDEX] = indices;

	RS::get_singleton()->mesh_clear(mesh);
	RS::get_singleton()->mesh_add_surface_from_arrays(mesh, RS::PRIMITIVE_TRIANGLES, arr);
}

void CPUParticles2D::set_texture(const Ref<Texture> &p_texture) {
	if (p_texture == texture) {
		return;
	}

	if (texture.is_valid()) {
		texture->disconnect(CoreStringNames::get_singleton()->changed, this, "_texture_changed");
	}

	texture = p_texture;

	if (texture.is_valid()) {
		texture->connect(CoreStringNames::get_singleton()->changed, this, "_texture_changed");
	}

	update();
	_update_mesh_texture();
}

void CPUParticles2D::_texture_changed() {
	if (texture.is_valid()) {
		update();
		_update_mesh_texture();
	}
}

Ref<Texture> CPUParticles2D::get_texture() const {
	return texture;
}

void CPUParticles2D::set_normalmap(const Ref<Texture> &p_normalmap) {
	normalmap = p_normalmap;
	update();
}

Ref<Texture> CPUParticles2D::get_normalmap() const {
	return normalmap;
}

void CPUParticles2D::set_fixed_fps(int p_count) {
	fixed_fps = p_count;
}

int CPUParticles2D::get_fixed_fps() const {
	return fixed_fps;
}

void CPUParticles2D::set_fractional_delta(bool p_enable) {
	fractional_delta = p_enable;
}

bool CPUParticles2D::get_fractional_delta() const {
	return fractional_delta;
}

String CPUParticles2D::get_configuration_warning() const {
	String warnings = Node2D::get_configuration_warning();

	CanvasItemMaterial *mat = Object::cast_to<CanvasItemMaterial>(get_material().ptr());

	if (get_material().is_null() || (mat && !mat->get_particles_animation())) {
		if (get_param(PARAM_ANIM_SPEED) != 0.0 || get_param(PARAM_ANIM_OFFSET) != 0.0 ||
				get_param_curve(PARAM_ANIM_SPEED).is_valid() || get_param_curve(PARAM_ANIM_OFFSET).is_valid()) {
			if (warnings != String()) {
				warnings += "\n\n";
			}
			warnings += "- " + TTR("CPUParticles2D animation requires the usage of a CanvasItemMaterial with \"Particles Animation\" enabled.");
		}
	}

	return warnings;
}

void CPUParticles2D::restart() {
	time = 0;
	inactive_time = 0;
	frame_remainder = 0;
	cycle = 0;
	emitting = false;

	{
		int pc = particles.size();
		PoolVector<Particle>::Write w = particles.write();

		for (int i = 0; i < pc; i++) {
			w[i].active = false;
		}
	}

	set_emitting(true);
}

void CPUParticles2D::set_direction(Vector2 p_direction) {
	direction = p_direction;
}

Vector2 CPUParticles2D::get_direction() const {
	return direction;
}

void CPUParticles2D::set_spread(float p_spread) {
	spread = p_spread;
}

float CPUParticles2D::get_spread() const {
	return spread;
}

void CPUParticles2D::set_param(Parameter p_param, float p_value) {
	ERR_FAIL_INDEX(p_param, PARAM_MAX);

	parameters[p_param] = p_value;
}
float CPUParticles2D::get_param(Parameter p_param) const {
	ERR_FAIL_INDEX_V(p_param, PARAM_MAX, 0);

	return parameters[p_param];
}

void CPUParticles2D::set_param_randomness(Parameter p_param, float p_value) {
	ERR_FAIL_INDEX(p_param, PARAM_MAX);

	randomness[p_param] = p_value;
}
float CPUParticles2D::get_param_randomness(Parameter p_param) const {
	ERR_FAIL_INDEX_V(p_param, PARAM_MAX, 0);

	return randomness[p_param];
}

static void _adjust_curve_range(const Ref<Curve> &p_curve, float p_min, float p_max) {
	Ref<Curve> curve = p_curve;
	if (!curve.is_valid()) {
		return;
	}

	curve->ensure_default_setup(p_min, p_max);
}

void CPUParticles2D::set_param_curve(Parameter p_param, const Ref<Curve> &p_curve) {
	ERR_FAIL_INDEX(p_param, PARAM_MAX);

	curve_parameters[p_param] = p_curve;

	switch (p_param) {
		case PARAM_INITIAL_LINEAR_VELOCITY: {
			//do none for this one
		} break;
		case PARAM_ANGULAR_VELOCITY: {
			_adjust_curve_range(p_curve, -360, 360);
		} break;
		case PARAM_ORBIT_VELOCITY: {
			_adjust_curve_range(p_curve, -500, 500);
		} break;
		case PARAM_LINEAR_ACCEL: {
			_adjust_curve_range(p_curve, -200, 200);
		} break;
		case PARAM_RADIAL_ACCEL: {
			_adjust_curve_range(p_curve, -200, 200);
		} break;
		case PARAM_TANGENTIAL_ACCEL: {
			_adjust_curve_range(p_curve, -200, 200);
		} break;
		case PARAM_DAMPING: {
			_adjust_curve_range(p_curve, 0, 100);
		} break;
		case PARAM_ANGLE: {
			_adjust_curve_range(p_curve, -360, 360);
		} break;
		case PARAM_SCALE: {
		} break;
		case PARAM_HUE_VARIATION: {
			_adjust_curve_range(p_curve, -1, 1);
		} break;
		case PARAM_ANIM_SPEED: {
			_adjust_curve_range(p_curve, 0, 200);
		} break;
		case PARAM_ANIM_OFFSET: {
		} break;
		default: {
		}
	}
}
Ref<Curve> CPUParticles2D::get_param_curve(Parameter p_param) const {
	ERR_FAIL_INDEX_V(p_param, PARAM_MAX, Ref<Curve>());

	return curve_parameters[p_param];
}

void CPUParticles2D::set_color(const Color &p_color) {
	color = p_color;
}

Color CPUParticles2D::get_color() const {
	return color;
}

void CPUParticles2D::set_color_ramp(const Ref<Gradient> &p_ramp) {
	color_ramp = p_ramp;
}

Ref<Gradient> CPUParticles2D::get_color_ramp() const {
	return color_ramp;
}

void CPUParticles2D::set_color_initial_ramp(const Ref<Gradient> &p_ramp) {
	color_initial_ramp = p_ramp;
}

Ref<Gradient> CPUParticles2D::get_color_initial_ramp() const {
	return color_initial_ramp;
}

void CPUParticles2D::set_particle_flag(Flags p_flag, bool p_enable) {
	ERR_FAIL_INDEX(p_flag, FLAG_MAX);
	flags[p_flag] = p_enable;
}

bool CPUParticles2D::get_particle_flag(Flags p_flag) const {
	ERR_FAIL_INDEX_V(p_flag, FLAG_MAX, false);
	return flags[p_flag];
}

void CPUParticles2D::set_emission_shape(EmissionShape p_shape) {
	ERR_FAIL_INDEX(p_shape, EMISSION_SHAPE_MAX);
	emission_shape = p_shape;
	_change_notify();
}

void CPUParticles2D::set_emission_sphere_radius(float p_radius) {
	emission_sphere_radius = p_radius;
}

void CPUParticles2D::set_emission_rect_extents(Vector2 p_extents) {
	emission_rect_extents = p_extents;
}

void CPUParticles2D::set_emission_points(const PoolVector<Vector2> &p_points) {
	emission_points = p_points;
}

void CPUParticles2D::set_emission_normals(const PoolVector<Vector2> &p_normals) {
	emission_normals = p_normals;
}

void CPUParticles2D::set_emission_colors(const PoolVector<Color> &p_colors) {
	emission_colors = p_colors;
}

float CPUParticles2D::get_emission_sphere_radius() const {
	return emission_sphere_radius;
}
Vector2 CPUParticles2D::get_emission_rect_extents() const {
	return emission_rect_extents;
}
PoolVector<Vector2> CPUParticles2D::get_emission_points() const {
	return emission_points;
}
PoolVector<Vector2> CPUParticles2D::get_emission_normals() const {
	return emission_normals;
}

PoolVector<Color> CPUParticles2D::get_emission_colors() const {
	return emission_colors;
}

CPUParticles2D::EmissionShape CPUParticles2D::get_emission_shape() const {
	return emission_shape;
}
void CPUParticles2D::set_gravity(const Vector2 &p_gravity) {
	gravity = p_gravity;
}

Vector2 CPUParticles2D::get_gravity() const {
	return gravity;
}

void CPUParticles2D::_validate_property(PropertyInfo &property) const {
	if (property.name == "emission_sphere_radius" && emission_shape != EMISSION_SHAPE_SPHERE) {
		property.usage = 0;
	}

	if (property.name == "emission_rect_extents" && emission_shape != EMISSION_SHAPE_RECTANGLE) {
		property.usage = 0;
	}

	if ((property.name == "emission_point_texture" || property.name == "emission_color_texture") && (emission_shape < EMISSION_SHAPE_POINTS)) {
		property.usage = 0;
	}

	if (property.name == "emission_normals" && emission_shape != EMISSION_SHAPE_DIRECTED_POINTS) {
		property.usage = 0;
	}

	if (property.name == "emission_points" && emission_shape != EMISSION_SHAPE_POINTS && emission_shape != EMISSION_SHAPE_DIRECTED_POINTS) {
		property.usage = 0;
	}

	if (property.name == "emission_colors" && emission_shape != EMISSION_SHAPE_POINTS && emission_shape != EMISSION_SHAPE_DIRECTED_POINTS) {
		property.usage = 0;
	}
}

static uint32_t idhash(uint32_t x) {
	x = ((x >> uint32_t(16)) ^ x) * uint32_t(0x45d9f3b);
	x = ((x >> uint32_t(16)) ^ x) * uint32_t(0x45d9f3b);
	x = (x >> uint32_t(16)) ^ x;
	return x;
}

static float rand_from_seed(uint32_t &seed) {
	int k;
	int s = int(seed);
	if (s == 0) {
		s = 305420679;
	}
	k = s / 127773;
	s = 16807 * (s - k * 127773) - 2836 * k;
	if (s < 0) {
		s += 2147483647;
	}
	seed = uint32_t(s);
	return float(seed % uint32_t(65536)) / 65535.0;
}

void CPUParticles2D::_update_internal(bool p_on_physics_tick) {
	if (particles.size() == 0 || !is_visible_in_tree()) {
		_set_redraw(false);
		return;
	}

	// Change update mode?
	_refresh_interpolation_state();

	float delta = 0.0f;

	// Is this update occurring on a physics tick (i.e. interpolated), or a frame tick?
	if (p_on_physics_tick) {
		delta = get_physics_process_delta_time();
	} else {
		delta = get_process_delta_time();
	}

	if (emitting) {
		inactive_time = 0;
	} else {
		inactive_time += delta;
		if (inactive_time > lifetime * 1.2) {
			set_process_internal(false);
			_set_redraw(false);

			//reset variables
			time = 0;
			inactive_time = 0;
			frame_remainder = 0;
			cycle = 0;
			return;
		}
	}
	_set_redraw(true);

	if (time == 0 && pre_process_time > 0.0) {
		float frame_time;
		if (fixed_fps > 0) {
			frame_time = 1.0 / fixed_fps;
		} else {
			frame_time = 1.0 / 30.0;
		}

		float todo = pre_process_time;

		while (todo >= 0) {
			_particles_process(frame_time);
			todo -= frame_time;
		}
	}

	if (fixed_fps > 0) {
		float frame_time = 1.0 / fixed_fps;
		float decr = frame_time;

		float ldelta = delta;
		if (ldelta > 0.1) { //avoid recursive stalls if fps goes below 10
			ldelta = 0.1;
		} else if (ldelta <= 0.0) { //unlikely but..
			ldelta = 0.001;
		}
		float todo = frame_remainder + ldelta;

		while (todo >= frame_time) {
			_particles_process(frame_time);
			todo -= decr;
		}

		frame_remainder = todo;

	} else {
		_particles_process(delta);
	}

	_update_particle_data_buffer();

	// If we are interpolating, we send the data to the VisualServer
	// right away on a physics tick instead of waiting until a render frame.
	if (p_on_physics_tick && redraw) {
		_update_render_thread();
	}
}

void CPUParticles2D::_particle_process(Particle &r_p, const Transform2D &p_emission_xform, float p_local_delta, float &r_tv) {
	uint32_t alt_seed = r_p.seed;

	r_p.time += p_local_delta;
	r_p.custom[1] = r_p.time / lifetime;
	r_tv = r_p.time / r_p.lifetime;

	float tex_linear_velocity = 0.0;
	if (curve_parameters[PARAM_INITIAL_LINEAR_VELOCITY].is_valid()) {
		tex_linear_velocity = curve_parameters[PARAM_INITIAL_LINEAR_VELOCITY]->interpolate(r_tv);
	}

	float tex_orbit_velocity = 0.0;
	if (curve_parameters[PARAM_ORBIT_VELOCITY].is_valid()) {
		tex_orbit_velocity = curve_parameters[PARAM_ORBIT_VELOCITY]->interpolate(r_tv);
	}

	float tex_angular_velocity = 0.0;
	if (curve_parameters[PARAM_ANGULAR_VELOCITY].is_valid()) {
		tex_angular_velocity = curve_parameters[PARAM_ANGULAR_VELOCITY]->interpolate(r_tv);
	}

	float tex_linear_accel = 0.0;
	if (curve_parameters[PARAM_LINEAR_ACCEL].is_valid()) {
		tex_linear_accel = curve_parameters[PARAM_LINEAR_ACCEL]->interpolate(r_tv);
	}

	float tex_tangential_accel = 0.0;
	if (curve_parameters[PARAM_TANGENTIAL_ACCEL].is_valid()) {
		tex_tangential_accel = curve_parameters[PARAM_TANGENTIAL_ACCEL]->interpolate(r_tv);
	}

	float tex_radial_accel = 0.0;
	if (curve_parameters[PARAM_RADIAL_ACCEL].is_valid()) {
		tex_radial_accel = curve_parameters[PARAM_RADIAL_ACCEL]->interpolate(r_tv);
	}

	float tex_damping = 0.0;
	if (curve_parameters[PARAM_DAMPING].is_valid()) {
		tex_damping = curve_parameters[PARAM_DAMPING]->interpolate(r_tv);
	}

	float tex_angle = 0.0;
	if (curve_parameters[PARAM_ANGLE].is_valid()) {
		tex_angle = curve_parameters[PARAM_ANGLE]->interpolate(r_tv);
	}
	float tex_anim_speed = 0.0;
	if (curve_parameters[PARAM_ANIM_SPEED].is_valid()) {
		tex_anim_speed = curve_parameters[PARAM_ANIM_SPEED]->interpolate(r_tv);
	}

	float tex_anim_offset = 0.0;
	if (curve_parameters[PARAM_ANIM_OFFSET].is_valid()) {
		tex_anim_offset = curve_parameters[PARAM_ANIM_OFFSET]->interpolate(r_tv);
	}

	Vector2 force = gravity;
	Vector2 pos = r_p.transform[2];

	// Apply linear acceleration.
	force += r_p.velocity.length() > 0.0 ? r_p.velocity.normalized() * (parameters[PARAM_LINEAR_ACCEL] + tex_linear_accel) * Math::lerp(1.0f, rand_from_seed(alt_seed), randomness[PARAM_LINEAR_ACCEL]) : Vector2();

	// Apply radial acceleration.
	Vector2 org = p_emission_xform[2];
	Vector2 diff = pos - org;
	force += diff.length() > 0.0 ? diff.normalized() * (parameters[PARAM_RADIAL_ACCEL] + tex_radial_accel) * Math::lerp(1.0f, rand_from_seed(alt_seed), randomness[PARAM_RADIAL_ACCEL]) : Vector2();

	// Apply tangential acceleration.
	Vector2 yx = Vector2(diff.y, diff.x);
	force += yx.length() > 0.0 ? (yx * Vector2(-1.0, 1.0)).normalized() * ((parameters[PARAM_TANGENTIAL_ACCEL] + tex_tangential_accel) * Math::lerp(1.0f, rand_from_seed(alt_seed), randomness[PARAM_TANGENTIAL_ACCEL])) : Vector2();

	// Apply attractor forces.
	r_p.velocity += force * p_local_delta;

	// Orbit velocity.
	float orbit_amount = (parameters[PARAM_ORBIT_VELOCITY] + tex_orbit_velocity) * Math::lerp(1.0f, rand_from_seed(alt_seed), randomness[PARAM_ORBIT_VELOCITY]);
	if (orbit_amount != 0.0) {
		float ang = orbit_amount * p_local_delta * Math_PI * 2.0;
		// Not sure why the ParticlesMaterial code uses a clockwise rotation matrix,
		// but we use -ang here to reproduce its behavior.
		Transform2D rot = Transform2D(-ang, Vector2());
		r_p.transform[2] -= diff;
		r_p.transform[2] += rot.basis_xform(diff);
	}
	if (curve_parameters[PARAM_INITIAL_LINEAR_VELOCITY].is_valid()) {
		r_p.velocity = r_p.velocity.normalized() * tex_linear_velocity;
	}

	if (parameters[PARAM_DAMPING] + tex_damping > 0.0) {
		float v = r_p.velocity.length();
		float damp = (parameters[PARAM_DAMPING] + tex_damping) * Math::lerp(1.0f, rand_from_seed(alt_seed), randomness[PARAM_DAMPING]);
		v -= damp * p_local_delta;
		if (v < 0.0) {
			r_p.velocity = Vector2();
		} else {
			r_p.velocity = r_p.velocity.normalized() * v;
		}
	}
	float base_angle = (parameters[PARAM_ANGLE] + tex_angle) * Math::lerp(1.0f, r_p.angle_rand, randomness[PARAM_ANGLE]);
	base_angle += r_p.custom[1] * lifetime * (parameters[PARAM_ANGULAR_VELOCITY] + tex_angular_velocity) * Math::lerp(1.0f, rand_from_seed(alt_seed) * 2.0f - 1.0f, randomness[PARAM_ANGULAR_VELOCITY]);
	r_p.rotation = Math::deg2rad(base_angle); //angle
	float animation_phase = (parameters[PARAM_ANIM_OFFSET] + tex_anim_offset) * Math::lerp(1.0f, r_p.anim_offset_rand, randomness[PARAM_ANIM_OFFSET]) + r_tv * (parameters[PARAM_ANIM_SPEED] + tex_anim_speed) * Math::lerp(1.0f, rand_from_seed(alt_seed), randomness[PARAM_ANIM_SPEED]);
	r_p.custom[2] = animation_phase;
}

void CPUParticles2D::_particles_process(float p_delta) {
	p_delta *= speed_scale;

	int pcount = particles.size();
	PoolVector<Particle>::Write w = particles.write();

	Particle *parray = w.ptr();

	float prev_time = time;
	time += p_delta;
	if (time > lifetime) {
		time = Math::fmod(time, lifetime);
		cycle++;
		if (one_shot && cycle > 0) {
			set_emitting(false);
			_change_notify();
		}
	}

	Transform2D emission_xform;
	Transform2D velocity_xform;
	if (!local_coords) {
		if (!_interpolation_data.interpolated_follow) {
			emission_xform = get_global_transform();
		} else {
			TransformInterpolator::interpolate_transform_2d(_interpolation_data.global_xform_prev, _interpolation_data.global_xform_curr, emission_xform, Engine::get_singleton()->get_physics_interpolation_fraction());
		}
		velocity_xform = emission_xform;
		velocity_xform[2] = Vector2();
	}

	float system_phase = time / lifetime;

	for (int i = 0; i < pcount; i++) {
		Particle &p = parray[i];

		if (!emitting && !p.active) {
			continue;
		}

		// For interpolation we need to keep a record of previous particles.
		if (_interpolated) {
			DEV_ASSERT((uint32_t)particles.size() == particles_prev.size());
			p.copy_to(particles_prev[i]);
		}

		float local_delta = p_delta;

		// The phase is a ratio between 0 (birth) and 1 (end of life) for each particle.
		// While we use time in tests later on, for randomness we use the phase as done in the
		// original shader code, and we later multiply by lifetime to get the time.
		float restart_phase = float(i) / float(pcount);

		if (randomness_ratio > 0.0) {
			uint32_t seed = cycle;
			if (restart_phase >= system_phase) {
				seed -= uint32_t(1);
			}
			seed *= uint32_t(pcount);
			seed += uint32_t(i);
			float random = float(idhash(seed) % uint32_t(65536)) / 65536.0;
			restart_phase += randomness_ratio * random * 1.0 / float(pcount);
		}

		restart_phase *= (1.0 - explosiveness_ratio);
		float restart_time = restart_phase * lifetime;
		bool restart = false;

		if (time > prev_time) {
			// restart_time >= prev_time is used so particles emit in the first frame they are processed

			if (restart_time >= prev_time && restart_time < time) {
				restart = true;
				if (fractional_delta) {
					local_delta = time - restart_time;
				}
			}

		} else if (local_delta > 0.0) {
			if (restart_time >= prev_time) {
				restart = true;
				if (fractional_delta) {
					local_delta = lifetime - restart_time + time;
				}

			} else if (restart_time < time) {
				restart = true;
				if (fractional_delta) {
					local_delta = time - restart_time;
				}
			}
		}

		if (p.time * (1.0 - explosiveness_ratio) > p.lifetime) {
			restart = true;
		}

		float tv = 0.0;

		if (restart) {
			if (!emitting) {
				p.active = false;
				continue;
			}
			p.active = true;

			/*float tex_linear_velocity = 0;
			if (curve_parameters[PARAM_INITIAL_LINEAR_VELOCITY].is_valid()) {
				tex_linear_velocity = curve_parameters[PARAM_INITIAL_LINEAR_VELOCITY]->interpolate(0);
			}*/

			float tex_angle = 0.0;
			if (curve_parameters[PARAM_ANGLE].is_valid()) {
				tex_angle = curve_parameters[PARAM_ANGLE]->interpolate(tv);
			}

			float tex_anim_offset = 0.0;
			if (curve_parameters[PARAM_ANGLE].is_valid()) {
				tex_anim_offset = curve_parameters[PARAM_ANGLE]->interpolate(tv);
			}

			p.seed = Math::rand();

			p.angle_rand = Math::randf();
			p.scale_rand = Math::randf();
			p.hue_rot_rand = Math::randf();
			p.anim_offset_rand = Math::randf();

			if (color_initial_ramp.is_valid()) {
				p.start_color_rand = color_initial_ramp->get_color_at_offset(Math::randf());
			} else {
				p.start_color_rand = Color(1, 1, 1, 1);
			}

			float angle1_rad = Math::atan2(direction.y, direction.x) + (Math::randf() * 2.0 - 1.0) * Math_PI * spread / 180.0;
			Vector2 rot = Vector2(Math::cos(angle1_rad), Math::sin(angle1_rad));
			p.velocity = rot * parameters[PARAM_INITIAL_LINEAR_VELOCITY] * Math::lerp(1.0f, float(Math::randf()), randomness[PARAM_INITIAL_LINEAR_VELOCITY]);

			float base_angle = (parameters[PARAM_ANGLE] + tex_angle) * Math::lerp(1.0f, p.angle_rand, randomness[PARAM_ANGLE]);
			p.rotation = Math::deg2rad(base_angle);

			p.custom[0] = 0.0; // unused
			p.custom[1] = 0.0; // phase [0..1]
			p.custom[2] = (parameters[PARAM_ANIM_OFFSET] + tex_anim_offset) * Math::lerp(1.0f, p.anim_offset_rand, randomness[PARAM_ANIM_OFFSET]); //animation phase [0..1]
			p.custom[3] = 0.0;
			p.transform = Transform2D();
			p.time = 0;
			p.lifetime = lifetime * (1.0 - Math::randf() * lifetime_randomness);
			p.base_color = Color(1, 1, 1, 1);

			switch (emission_shape) {
				case EMISSION_SHAPE_POINT: {
					//do none
				} break;
				case EMISSION_SHAPE_SPHERE: {
					float s = Math::randf(), t = 2.0 * Math_PI * Math::randf();
					float radius = emission_sphere_radius * Math::sqrt(1.0 - s * s);
					p.transform[2] = Vector2(Math::cos(t), Math::sin(t)) * radius;
				} break;
				case EMISSION_SHAPE_RECTANGLE: {
					p.transform[2] = Vector2(Math::randf() * 2.0 - 1.0, Math::randf() * 2.0 - 1.0) * emission_rect_extents;
				} break;
				case EMISSION_SHAPE_POINTS:
				case EMISSION_SHAPE_DIRECTED_POINTS: {
					int pc = emission_points.size();
					if (pc == 0) {
						break;
					}

					int random_idx = Math::rand() % pc;

					p.transform[2] = emission_points.get(random_idx);

					if (emission_shape == EMISSION_SHAPE_DIRECTED_POINTS && emission_normals.size() == pc) {
						Vector2 normal = emission_normals.get(random_idx);
						Transform2D m2;
						m2.set_axis(0, normal);
						m2.set_axis(1, normal.tangent());
						p.velocity = m2.basis_xform(p.velocity);
					}

					if (emission_colors.size() == pc) {
						p.base_color = emission_colors.get(random_idx);
					}
				} break;
				case EMISSION_SHAPE_MAX: { // Max value for validity check.
					break;
				}
			}

			if (!local_coords) {
				p.velocity = velocity_xform.xform(p.velocity);
				p.transform = emission_xform * p.transform;
			}

		} else if (!p.active) {
			continue;
		} else if (p.time > p.lifetime) {
			p.active = false;
			tv = 1.0;
		} else {
			_particle_process(p, emission_xform, local_delta, tv);
		}
		//apply color
		//apply hue rotation

		float tex_scale = 1.0;
		if (curve_parameters[PARAM_SCALE].is_valid()) {
			tex_scale = curve_parameters[PARAM_SCALE]->interpolate(tv);
		}

		float tex_hue_variation = 0.0;
		if (curve_parameters[PARAM_HUE_VARIATION].is_valid()) {
			tex_hue_variation = curve_parameters[PARAM_HUE_VARIATION]->interpolate(tv);
		}

		float hue_rot_angle = (parameters[PARAM_HUE_VARIATION] + tex_hue_variation) * Math_PI * 2.0 * Math::lerp(1.0f, p.hue_rot_rand * 2.0f - 1.0f, randomness[PARAM_HUE_VARIATION]);
		float hue_rot_c = Math::cos(hue_rot_angle);
		float hue_rot_s = Math::sin(hue_rot_angle);

		Basis hue_rot_mat;
		{
			Basis mat1(0.299, 0.587, 0.114, 0.299, 0.587, 0.114, 0.299, 0.587, 0.114);
			Basis mat2(0.701, -0.587, -0.114, -0.299, 0.413, -0.114, -0.300, -0.588, 0.886);
			Basis mat3(0.168, 0.330, -0.497, -0.328, 0.035, 0.292, 1.250, -1.050, -0.203);

			for (int j = 0; j < 3; j++) {
				hue_rot_mat[j] = mat1[j] + mat2[j] * hue_rot_c + mat3[j] * hue_rot_s;
			}
		}

		if (color_ramp.is_valid()) {
			p.color = color_ramp->get_color_at_offset(tv) * color;
		} else {
			p.color = color;
		}

		Vector3 color_rgb = hue_rot_mat.xform_inv(Vector3(p.color.r, p.color.g, p.color.b));
		p.color.r = color_rgb.x;
		p.color.g = color_rgb.y;
		p.color.b = color_rgb.z;

		p.color *= p.base_color * p.start_color_rand;

		if (flags[FLAG_ALIGN_Y_TO_VELOCITY]) {
			if (p.velocity.length() > 0.0) {
				p.transform.columns[1] = p.velocity.normalized();
				p.transform.columns[0] = p.transform.columns[1].tangent();
			}

		} else {
			p.transform.columns[0] = Vector2(Math::cos(p.rotation), -Math::sin(p.rotation));
			p.transform.columns[1] = Vector2(Math::sin(p.rotation), Math::cos(p.rotation));
		}

		//scale by scale
		float base_scale = tex_scale * Math::lerp(parameters[PARAM_SCALE], 1.0f, p.scale_rand * randomness[PARAM_SCALE]);

		// Prevent zero scale (which can cause rendering issues).
		base_scale = SGN(base_scale) * MAX(Math::abs(base_scale), 0.000001);

		p.transform.columns[0] *= base_scale;
		p.transform.columns[1] *= base_scale;

		p.transform[2] += p.velocity * local_delta;

		// Teleport if starting a new particle, so
		// we don't get a streak from the old position
		// to this new start.
		if (restart && _interpolated) {
			p.copy_to(particles_prev[i]);
		}
	}
}

void CPUParticles2D::_update_particle_data_buffer() {
	update_mutex.lock();

	{
		int pc = particles.size();

		PoolVector<int>::Write ow;
		int *order = nullptr;

		PoolVector<float>::Write w = particle_data.write();
		PoolVector<Particle>::Read r = particles.read();
		float *ptr = w.ptr();

		PoolVector<float>::Write w_prev;
		float *ptr_prev = nullptr;

		if (_interpolated) {
			DEV_ASSERT(particle_data.size() == particle_data_prev.size());
			w_prev = particle_data_prev.write();
			ptr_prev = w_prev.ptr();
		}

		if (draw_order != DRAW_ORDER_INDEX) {
			ow = particle_order.write();
			order = ow.ptr();

			for (int i = 0; i < pc; i++) {
				order[i] = i;
			}
			if (draw_order == DRAW_ORDER_LIFETIME) {
				SortArray<int, SortLifetime> sorter;
				sorter.compare.particles = r.ptr();
				sorter.sort(order, pc);
			}
		}

		if (_interpolated) {
			for (int i = 0; i < pc; i++) {
				int idx = order ? order[i] : i;
				_fill_particle_data<false>(r[idx], ptr, r[idx].active);
				ptr += 13;
				_fill_particle_data<false>(particles_prev[idx], ptr_prev, r[idx].active);
				ptr_prev += 13;
			}
		} else {
#ifdef PANDEMONIUM_CPU_PARTICLES_2D_LEGACY_COMPATIBILITY
			if (!local_coords) {
				inv_emission_transform = get_global_transform().affine_inverse();
				for (int i = 0; i < pc; i++) {
					int idx = order ? order[i] : i;
					_fill_particle_data<true>(r[idx], ptr, r[idx].active);
					ptr += 13;
				}
			} else {
				for (int i = 0; i < pc; i++) {
					int idx = order ? order[i] : i;
					_fill_particle_data<false>(r[idx], ptr, r[idx].active);
					ptr += 13;
				}
			}
#else
			for (int i = 0; i < pc; i++) {
				int idx = order ? order[i] : i;
				_fill_particle_data<false>(r[idx], ptr, r[idx].active);
				ptr += 13;
			}
#endif
		}
	}

	update_mutex.unlock();
}

void CPUParticles2D::_refresh_interpolation_state() {
	if (!is_inside_tree()) {
		return;
	}
	bool interpolated = is_physics_interpolated_and_enabled();

	// The logic for whether to do an interpolated follow.
	// This is rather complex, but basically:
	// If project setting interpolation is ON but this particle system is switched OFF,
	// and in global mode, we will follow the INTERPOLATED position rather than the actual position.
	// This is so that particles aren't generated AHEAD of the interpolated parent.
	bool follow = !interpolated && !local_coords && get_tree()->is_physics_interpolation_enabled();

	if ((_interpolated == interpolated) && (follow == _interpolation_data.interpolated_follow)) {
		return;
	}

	bool curr_redraw = redraw;

	// Remove all connections.
	// This isn't super efficient, but should only happen rarely.
	_set_redraw(false);

	_interpolated = interpolated;
	_interpolation_data.interpolated_follow = follow;

	// Refresh local coords state, blank inv_emission_transform.
	set_use_local_coordinates(local_coords);

	set_process_internal(!_interpolated);
	set_physics_process_internal(_interpolated || _interpolation_data.interpolated_follow);

	// Re-establish all connections.
	_set_redraw(curr_redraw);
}

void CPUParticles2D::_set_redraw(bool p_redraw) {
	if (redraw == p_redraw) {
		return;
	}
	redraw = p_redraw;
	update_mutex.lock();

	if (!_interpolated) {
		if (redraw) {
			RS::get_singleton()->connect("frame_pre_draw", this, "_update_render_thread");
		} else {
			if (RS::get_singleton()->is_connected("frame_pre_draw", this, "_update_render_thread")) {
				RS::get_singleton()->disconnect("frame_pre_draw", this, "_update_render_thread");
			}
		}
	}

	if (redraw) {
		RS::get_singleton()->canvas_item_set_update_when_visible(get_canvas_item(), true);

		RS::get_singleton()->multimesh_set_visible_instances(multimesh, -1);
	} else {
		RS::get_singleton()->canvas_item_set_update_when_visible(get_canvas_item(), false);

		RS::get_singleton()->multimesh_set_visible_instances(multimesh, 0);
	}
	update_mutex.unlock();
	update(); // redraw to update render list
}

void CPUParticles2D::_update_render_thread() {
	if (OS::get_singleton()->is_update_pending(true)) {
		update_mutex.lock();
		if (_interpolated) {
			RS::get_singleton()->multimesh_set_as_bulk_array_interpolated(multimesh, particle_data, particle_data_prev);
		} else {
			RS::get_singleton()->multimesh_set_as_bulk_array(multimesh, particle_data);
		}
		update_mutex.unlock();
	}
}

void CPUParticles2D::_notification(int p_what) {
	if (p_what == NOTIFICATION_ENTER_TREE) {
		set_process_internal(emitting);

		// For interpolated version to update the particles right away,
		// we need a sequence of events.
		// First ensure we are in _interpolated mode if the Node is set to interpolated.
		_refresh_interpolation_state();

		// Now, if we are interpolating, we want to force a single tick update.
		// If we don't do this, it may be an entire tick before the first update happens.
		if (_interpolated) {
			_update_internal(true);
		}

		// If we are interpolated following, then reset physics interpolation
		// when first appearing. This won't be called by canvas item, as in
		// following mode, is_interpolated() is actually FALSE.
		if (_interpolation_data.interpolated_follow) {
			notification(NOTIFICATION_RESET_PHYSICS_INTERPOLATION);
		}
	}

	if (p_what == NOTIFICATION_EXIT_TREE) {
		_set_redraw(false);
	}

	if (p_what == NOTIFICATION_DRAW) {
		// first update before rendering to avoid one frame delay after emitting starts
		if (emitting && (time == 0) && !_interpolated) {
			_update_internal(false);
		}

		if (!redraw) {
			return; // don't add to render list
		}

		RID texrid;
		if (texture.is_valid()) {
			texrid = texture->get_rid();
		}

		RID normrid;
		if (normalmap.is_valid()) {
			normrid = normalmap->get_rid();
		}

		RS::get_singleton()->canvas_item_add_multimesh(get_canvas_item(), multimesh, texrid, normrid);
	}

	if (p_what == NOTIFICATION_INTERNAL_PROCESS) {
		_update_internal(false);
	}

	if (p_what == NOTIFICATION_INTERNAL_PHYSICS_PROCESS) {
		if (_interpolated) {
			_update_internal(true);
		}
		if (_interpolation_data.interpolated_follow) {
			// Keep the interpolated follow target updated.
			DEV_CHECK_ONCE(!_interpolated);
			_interpolation_data.global_xform_prev = _interpolation_data.global_xform_curr;
			_interpolation_data.global_xform_curr = get_global_transform();
		}
	}
#ifdef PANDEMONIUM_CPU_PARTICLES_2D_LEGACY_COMPATIBILITY
	if (p_what == NOTIFICATION_TRANSFORM_CHANGED) {
		if (!_interpolated && !local_coords) {
			inv_emission_transform = get_global_transform().affine_inverse();
			int pc = particles.size();

			PoolVector<float>::Write w = particle_data.write();
			PoolVector<Particle>::Read r = particles.read();
			float *ptr = w.ptr();

			for (int i = 0; i < pc; i++) {
				Transform2D t = inv_emission_transform * r[i].transform;

				if (r[i].active) {
					ptr[0] = t.columns[0][0];
					ptr[1] = t.columns[1][0];
					ptr[2] = 0;
					ptr[3] = t.columns[2][0];
					ptr[4] = t.columns[0][1];
					ptr[5] = t.columns[1][1];
					ptr[6] = 0;
					ptr[7] = t.columns[2][1];

				} else {
					memset(ptr, 0, sizeof(float) * 8);
				}

				ptr += 13;
			}
		}
	}
#else
	if (p_what == NOTIFICATION_TRANSFORM_CHANGED) {
		if (_interpolation_data.interpolated_follow) {
			// If the transform has been updated AFTER the physics tick, keep data flowing.
			if (Engine::get_singleton()->is_in_physics_frame()) {
				_interpolation_data.global_xform_curr = get_global_transform();
			}
		}
	}
	if (p_what == NOTIFICATION_RESET_PHYSICS_INTERPOLATION) {
		// Make sure current is up to date with any pending global transform changes.
		_interpolation_data.global_xform_curr = get_global_transform_const();
		_interpolation_data.global_xform_prev = _interpolation_data.global_xform_curr;
	}
#endif
}

void CPUParticles2D::_bind_methods() {
	ClassDB::bind_method(D_METHOD("set_emitting", "emitting"), &CPUParticles2D::set_emitting);
	ClassDB::bind_method(D_METHOD("set_amount", "amount"), &CPUParticles2D::set_amount);
	ClassDB::bind_method(D_METHOD("set_lifetime", "secs"), &CPUParticles2D::set_lifetime);
	ClassDB::bind_method(D_METHOD("set_one_shot", "enable"), &CPUParticles2D::set_one_shot);
	ClassDB::bind_method(D_METHOD("set_pre_process_time", "secs"), &CPUParticles2D::set_pre_process_time);
	ClassDB::bind_method(D_METHOD("set_explosiveness_ratio", "ratio"), &CPUParticles2D::set_explosiveness_ratio);
	ClassDB::bind_method(D_METHOD("set_randomness_ratio", "ratio"), &CPUParticles2D::set_randomness_ratio);
	ClassDB::bind_method(D_METHOD("set_lifetime_randomness", "random"), &CPUParticles2D::set_lifetime_randomness);
	ClassDB::bind_method(D_METHOD("set_use_local_coordinates", "enable"), &CPUParticles2D::set_use_local_coordinates);
	ClassDB::bind_method(D_METHOD("set_fixed_fps", "fps"), &CPUParticles2D::set_fixed_fps);
	ClassDB::bind_method(D_METHOD("set_fractional_delta", "enable"), &CPUParticles2D::set_fractional_delta);
	ClassDB::bind_method(D_METHOD("set_speed_scale", "scale"), &CPUParticles2D::set_speed_scale);

	ClassDB::bind_method(D_METHOD("is_emitting"), &CPUParticles2D::is_emitting);
	ClassDB::bind_method(D_METHOD("get_amount"), &CPUParticles2D::get_amount);
	ClassDB::bind_method(D_METHOD("get_lifetime"), &CPUParticles2D::get_lifetime);
	ClassDB::bind_method(D_METHOD("get_one_shot"), &CPUParticles2D::get_one_shot);
	ClassDB::bind_method(D_METHOD("get_pre_process_time"), &CPUParticles2D::get_pre_process_time);
	ClassDB::bind_method(D_METHOD("get_explosiveness_ratio"), &CPUParticles2D::get_explosiveness_ratio);
	ClassDB::bind_method(D_METHOD("get_randomness_ratio"), &CPUParticles2D::get_randomness_ratio);
	ClassDB::bind_method(D_METHOD("get_lifetime_randomness"), &CPUParticles2D::get_lifetime_randomness);
	ClassDB::bind_method(D_METHOD("get_use_local_coordinates"), &CPUParticles2D::get_use_local_coordinates);
	ClassDB::bind_method(D_METHOD("get_fixed_fps"), &CPUParticles2D::get_fixed_fps);
	ClassDB::bind_method(D_METHOD("get_fractional_delta"), &CPUParticles2D::get_fractional_delta);
	ClassDB::bind_method(D_METHOD("get_speed_scale"), &CPUParticles2D::get_speed_scale);

	ClassDB::bind_method(D_METHOD("set_draw_order", "order"), &CPUParticles2D::set_draw_order);

	ClassDB::bind_method(D_METHOD("get_draw_order"), &CPUParticles2D::get_draw_order);

	ClassDB::bind_method(D_METHOD("set_texture", "texture"), &CPUParticles2D::set_texture);
	ClassDB::bind_method(D_METHOD("get_texture"), &CPUParticles2D::get_texture);

	ClassDB::bind_method(D_METHOD("set_normalmap", "normalmap"), &CPUParticles2D::set_normalmap);
	ClassDB::bind_method(D_METHOD("get_normalmap"), &CPUParticles2D::get_normalmap);

	ClassDB::bind_method(D_METHOD("restart"), &CPUParticles2D::restart);

	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "emitting"), "set_emitting", "is_emitting");
	ADD_PROPERTY(PropertyInfo(Variant::INT, "amount", PROPERTY_HINT_EXP_RANGE, "1,1000000,1"), "set_amount", "get_amount");
	ADD_GROUP("Time", "");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "lifetime", PROPERTY_HINT_RANGE, "0.01,600.0,0.01,or_greater"), "set_lifetime", "get_lifetime");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "one_shot"), "set_one_shot", "get_one_shot");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "preprocess", PROPERTY_HINT_RANGE, "0.00,600.0,0.01"), "set_pre_process_time", "get_pre_process_time");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "speed_scale", PROPERTY_HINT_RANGE, "0,64,0.01"), "set_speed_scale", "get_speed_scale");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "explosiveness", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_explosiveness_ratio", "get_explosiveness_ratio");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "randomness", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_randomness_ratio", "get_randomness_ratio");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "lifetime_randomness", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_lifetime_randomness", "get_lifetime_randomness");
	ADD_PROPERTY(PropertyInfo(Variant::INT, "fixed_fps", PROPERTY_HINT_RANGE, "0,1000,1"), "set_fixed_fps", "get_fixed_fps");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "fract_delta"), "set_fractional_delta", "get_fractional_delta");
	ADD_GROUP("Drawing", "");
	// No visibility_rect property contrarily to Particles2D, it's updated automatically.
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "local_coords"), "set_use_local_coordinates", "get_use_local_coordinates");
	ADD_PROPERTY(PropertyInfo(Variant::INT, "draw_order", PROPERTY_HINT_ENUM, "Index,Lifetime"), "set_draw_order", "get_draw_order");
	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "texture", PROPERTY_HINT_RESOURCE_TYPE, "Texture"), "set_texture", "get_texture");
	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "normalmap", PROPERTY_HINT_RESOURCE_TYPE, "Texture"), "set_normalmap", "get_normalmap");

	BIND_ENUM_CONSTANT(DRAW_ORDER_INDEX);
	BIND_ENUM_CONSTANT(DRAW_ORDER_LIFETIME);

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

	ClassDB::bind_method(D_METHOD("set_direction", "direction"), &CPUParticles2D::set_direction);
	ClassDB::bind_method(D_METHOD("get_direction"), &CPUParticles2D::get_direction);

	ClassDB::bind_method(D_METHOD("set_spread", "degrees"), &CPUParticles2D::set_spread);
	ClassDB::bind_method(D_METHOD("get_spread"), &CPUParticles2D::get_spread);

	ClassDB::bind_method(D_METHOD("set_param", "param", "value"), &CPUParticles2D::set_param);
	ClassDB::bind_method(D_METHOD("get_param", "param"), &CPUParticles2D::get_param);

	ClassDB::bind_method(D_METHOD("set_param_randomness", "param", "randomness"), &CPUParticles2D::set_param_randomness);
	ClassDB::bind_method(D_METHOD("get_param_randomness", "param"), &CPUParticles2D::get_param_randomness);

	ClassDB::bind_method(D_METHOD("set_param_curve", "param", "curve"), &CPUParticles2D::set_param_curve);
	ClassDB::bind_method(D_METHOD("get_param_curve", "param"), &CPUParticles2D::get_param_curve);

	ClassDB::bind_method(D_METHOD("set_color", "color"), &CPUParticles2D::set_color);
	ClassDB::bind_method(D_METHOD("get_color"), &CPUParticles2D::get_color);

	ClassDB::bind_method(D_METHOD("set_color_ramp", "ramp"), &CPUParticles2D::set_color_ramp);
	ClassDB::bind_method(D_METHOD("get_color_ramp"), &CPUParticles2D::get_color_ramp);

	ClassDB::bind_method(D_METHOD("set_color_initial_ramp", "ramp"), &CPUParticles2D::set_color_initial_ramp);
	ClassDB::bind_method(D_METHOD("get_color_initial_ramp"), &CPUParticles2D::get_color_initial_ramp);

	ClassDB::bind_method(D_METHOD("set_particle_flag", "flag", "enable"), &CPUParticles2D::set_particle_flag);
	ClassDB::bind_method(D_METHOD("get_particle_flag", "flag"), &CPUParticles2D::get_particle_flag);

	ClassDB::bind_method(D_METHOD("set_emission_shape", "shape"), &CPUParticles2D::set_emission_shape);
	ClassDB::bind_method(D_METHOD("get_emission_shape"), &CPUParticles2D::get_emission_shape);

	ClassDB::bind_method(D_METHOD("set_emission_sphere_radius", "radius"), &CPUParticles2D::set_emission_sphere_radius);
	ClassDB::bind_method(D_METHOD("get_emission_sphere_radius"), &CPUParticles2D::get_emission_sphere_radius);

	ClassDB::bind_method(D_METHOD("set_emission_rect_extents", "extents"), &CPUParticles2D::set_emission_rect_extents);
	ClassDB::bind_method(D_METHOD("get_emission_rect_extents"), &CPUParticles2D::get_emission_rect_extents);

	ClassDB::bind_method(D_METHOD("set_emission_points", "array"), &CPUParticles2D::set_emission_points);
	ClassDB::bind_method(D_METHOD("get_emission_points"), &CPUParticles2D::get_emission_points);

	ClassDB::bind_method(D_METHOD("set_emission_normals", "array"), &CPUParticles2D::set_emission_normals);
	ClassDB::bind_method(D_METHOD("get_emission_normals"), &CPUParticles2D::get_emission_normals);

	ClassDB::bind_method(D_METHOD("set_emission_colors", "array"), &CPUParticles2D::set_emission_colors);
	ClassDB::bind_method(D_METHOD("get_emission_colors"), &CPUParticles2D::get_emission_colors);

	ClassDB::bind_method(D_METHOD("get_gravity"), &CPUParticles2D::get_gravity);
	ClassDB::bind_method(D_METHOD("set_gravity", "accel_vec"), &CPUParticles2D::set_gravity);

	ClassDB::bind_method(D_METHOD("_update_render_thread"), &CPUParticles2D::_update_render_thread);
	ClassDB::bind_method(D_METHOD("_texture_changed"), &CPUParticles2D::_texture_changed);

	ADD_GROUP("Emission Shape", "emission_");
	ADD_PROPERTY(PropertyInfo(Variant::INT, "emission_shape", PROPERTY_HINT_ENUM, "Point,Sphere,Rectangle,Points,Directed Points", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_UPDATE_ALL_IF_MODIFIED), "set_emission_shape", "get_emission_shape");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "emission_sphere_radius", PROPERTY_HINT_RANGE, "0.01,128,0.01,or_greater"), "set_emission_sphere_radius", "get_emission_sphere_radius");
	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2, "emission_rect_extents"), "set_emission_rect_extents", "get_emission_rect_extents");
	ADD_PROPERTY(PropertyInfo(Variant::POOL_VECTOR2_ARRAY, "emission_points"), "set_emission_points", "get_emission_points");
	ADD_PROPERTY(PropertyInfo(Variant::POOL_VECTOR2_ARRAY, "emission_normals"), "set_emission_normals", "get_emission_normals");
	ADD_PROPERTY(PropertyInfo(Variant::POOL_COLOR_ARRAY, "emission_colors"), "set_emission_colors", "get_emission_colors");
	ADD_GROUP("Flags", "flag_");
	ADD_PROPERTYI(PropertyInfo(Variant::BOOL, "flag_align_y"), "set_particle_flag", "get_particle_flag", FLAG_ALIGN_Y_TO_VELOCITY);
	ADD_GROUP("Direction", "");
	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2, "direction"), "set_direction", "get_direction");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "spread", PROPERTY_HINT_RANGE, "0,180,0.01"), "set_spread", "get_spread");
	ADD_GROUP("Gravity", "");
	ADD_PROPERTY(PropertyInfo(Variant::VECTOR2, "gravity"), "set_gravity", "get_gravity");
	ADD_GROUP("Initial Velocity", "initial_");
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "initial_velocity", PROPERTY_HINT_RANGE, "0,1000,0.01,or_greater"), "set_param", "get_param", PARAM_INITIAL_LINEAR_VELOCITY);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "initial_velocity_random", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_param_randomness", "get_param_randomness", PARAM_INITIAL_LINEAR_VELOCITY);
	ADD_GROUP("Angular Velocity", "angular_");
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "angular_velocity", PROPERTY_HINT_RANGE, "-720,720,0.01,or_lesser,or_greater"), "set_param", "get_param", PARAM_ANGULAR_VELOCITY);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "angular_velocity_random", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_param_randomness", "get_param_randomness", PARAM_ANGULAR_VELOCITY);
	ADD_PROPERTYI(PropertyInfo(Variant::OBJECT, "angular_velocity_curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve"), "set_param_curve", "get_param_curve", PARAM_ANGULAR_VELOCITY);
	ADD_GROUP("Orbit Velocity", "orbit_");
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "orbit_velocity", PROPERTY_HINT_RANGE, "-1000,1000,0.01,or_lesser,or_greater"), "set_param", "get_param", PARAM_ORBIT_VELOCITY);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "orbit_velocity_random", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_param_randomness", "get_param_randomness", PARAM_ORBIT_VELOCITY);
	ADD_PROPERTYI(PropertyInfo(Variant::OBJECT, "orbit_velocity_curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve"), "set_param_curve", "get_param_curve", PARAM_ORBIT_VELOCITY);
	ADD_GROUP("Linear Accel", "linear_");
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "linear_accel", PROPERTY_HINT_RANGE, "-100,100,0.01,or_lesser,or_greater"), "set_param", "get_param", PARAM_LINEAR_ACCEL);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "linear_accel_random", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_param_randomness", "get_param_randomness", PARAM_LINEAR_ACCEL);
	ADD_PROPERTYI(PropertyInfo(Variant::OBJECT, "linear_accel_curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve"), "set_param_curve", "get_param_curve", PARAM_LINEAR_ACCEL);
	ADD_GROUP("Radial Accel", "radial_");
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "radial_accel", PROPERTY_HINT_RANGE, "-100,100,0.01,or_lesser,or_greater"), "set_param", "get_param", PARAM_RADIAL_ACCEL);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "radial_accel_random", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_param_randomness", "get_param_randomness", PARAM_RADIAL_ACCEL);
	ADD_PROPERTYI(PropertyInfo(Variant::OBJECT, "radial_accel_curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve"), "set_param_curve", "get_param_curve", PARAM_RADIAL_ACCEL);
	ADD_GROUP("Tangential Accel", "tangential_");
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "tangential_accel", PROPERTY_HINT_RANGE, "-100,100,0.01,or_lesser,or_greater"), "set_param", "get_param", PARAM_TANGENTIAL_ACCEL);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "tangential_accel_random", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_param_randomness", "get_param_randomness", PARAM_TANGENTIAL_ACCEL);
	ADD_PROPERTYI(PropertyInfo(Variant::OBJECT, "tangential_accel_curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve"), "set_param_curve", "get_param_curve", PARAM_TANGENTIAL_ACCEL);
	ADD_GROUP("Damping", "");
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "damping", PROPERTY_HINT_RANGE, "0,100,0.01,or_greater"), "set_param", "get_param", PARAM_DAMPING);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "damping_random", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_param_randomness", "get_param_randomness", PARAM_DAMPING);
	ADD_PROPERTYI(PropertyInfo(Variant::OBJECT, "damping_curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve"), "set_param_curve", "get_param_curve", PARAM_DAMPING);
	ADD_GROUP("Angle", "");
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "angle", PROPERTY_HINT_RANGE, "-720,720,0.1,or_lesser,or_greater"), "set_param", "get_param", PARAM_ANGLE);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "angle_random", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_param_randomness", "get_param_randomness", PARAM_ANGLE);
	ADD_PROPERTYI(PropertyInfo(Variant::OBJECT, "angle_curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve"), "set_param_curve", "get_param_curve", PARAM_ANGLE);
	ADD_GROUP("Scale", "");
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "scale_amount", PROPERTY_HINT_RANGE, "-1000,1000,0.01,or_greater"), "set_param", "get_param", PARAM_SCALE);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "scale_amount_random", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_param_randomness", "get_param_randomness", PARAM_SCALE);
	ADD_PROPERTYI(PropertyInfo(Variant::OBJECT, "scale_amount_curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve"), "set_param_curve", "get_param_curve", PARAM_SCALE);
	ADD_GROUP("Color", "");
	ADD_PROPERTY(PropertyInfo(Variant::COLOR, "color"), "set_color", "get_color");
	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "color_ramp", PROPERTY_HINT_RESOURCE_TYPE, "Gradient"), "set_color_ramp", "get_color_ramp");
	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "color_initial_ramp", PROPERTY_HINT_RESOURCE_TYPE, "Gradient"), "set_color_initial_ramp", "get_color_initial_ramp");

	ADD_GROUP("Hue Variation", "hue_");
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "hue_variation", PROPERTY_HINT_RANGE, "-1,1,0.01"), "set_param", "get_param", PARAM_HUE_VARIATION);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "hue_variation_random", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_param_randomness", "get_param_randomness", PARAM_HUE_VARIATION);
	ADD_PROPERTYI(PropertyInfo(Variant::OBJECT, "hue_variation_curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve"), "set_param_curve", "get_param_curve", PARAM_HUE_VARIATION);
	ADD_GROUP("Animation", "anim_");
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "anim_speed", PROPERTY_HINT_RANGE, "0,128,0.01,or_greater"), "set_param", "get_param", PARAM_ANIM_SPEED);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "anim_speed_random", PROPERTY_HINT_RANGE, "0,1,0.01"), "set_param_randomness", "get_param_randomness", PARAM_ANIM_SPEED);
	ADD_PROPERTYI(PropertyInfo(Variant::OBJECT, "anim_speed_curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve"), "set_param_curve", "get_param_curve", PARAM_ANIM_SPEED);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "anim_offset", PROPERTY_HINT_RANGE, "0,1,0.0001"), "set_param", "get_param", PARAM_ANIM_OFFSET);
	ADD_PROPERTYI(PropertyInfo(Variant::REAL, "anim_offset_random", PROPERTY_HINT_RANGE, "0,1,0.0001"), "set_param_randomness", "get_param_randomness", PARAM_ANIM_OFFSET);
	ADD_PROPERTYI(PropertyInfo(Variant::OBJECT, "anim_offset_curve", PROPERTY_HINT_RESOURCE_TYPE, "Curve"), "set_param_curve", "get_param_curve", PARAM_ANIM_OFFSET);

	BIND_ENUM_CONSTANT(PARAM_INITIAL_LINEAR_VELOCITY);
	BIND_ENUM_CONSTANT(PARAM_ANGULAR_VELOCITY);
	BIND_ENUM_CONSTANT(PARAM_ORBIT_VELOCITY);
	BIND_ENUM_CONSTANT(PARAM_LINEAR_ACCEL);
	BIND_ENUM_CONSTANT(PARAM_RADIAL_ACCEL);
	BIND_ENUM_CONSTANT(PARAM_TANGENTIAL_ACCEL);
	BIND_ENUM_CONSTANT(PARAM_DAMPING);
	BIND_ENUM_CONSTANT(PARAM_ANGLE);
	BIND_ENUM_CONSTANT(PARAM_SCALE);
	BIND_ENUM_CONSTANT(PARAM_HUE_VARIATION);
	BIND_ENUM_CONSTANT(PARAM_ANIM_SPEED);
	BIND_ENUM_CONSTANT(PARAM_ANIM_OFFSET);
	BIND_ENUM_CONSTANT(PARAM_MAX);

	BIND_ENUM_CONSTANT(FLAG_ALIGN_Y_TO_VELOCITY);
	BIND_ENUM_CONSTANT(FLAG_ROTATE_Y); // Unused, but exposed for consistency with 3D.
	BIND_ENUM_CONSTANT(FLAG_DISABLE_Z); // Unused, but exposed for consistency with 3D.
	BIND_ENUM_CONSTANT(FLAG_MAX);

	BIND_ENUM_CONSTANT(EMISSION_SHAPE_POINT);
	BIND_ENUM_CONSTANT(EMISSION_SHAPE_SPHERE);
	BIND_ENUM_CONSTANT(EMISSION_SHAPE_RECTANGLE);
	BIND_ENUM_CONSTANT(EMISSION_SHAPE_POINTS);
	BIND_ENUM_CONSTANT(EMISSION_SHAPE_DIRECTED_POINTS);
	BIND_ENUM_CONSTANT(EMISSION_SHAPE_MAX);
}

CPUParticles2D::CPUParticles2D() {
	time = 0;
	inactive_time = 0;
	frame_remainder = 0;
	cycle = 0;
	redraw = false;
	emitting = false;
	_interpolated = false;
	_interpolation_data.interpolated_follow = false;

	mesh = RID_PRIME(RenderingServer::get_singleton()->mesh_create());
	multimesh = RID_PRIME(RenderingServer::get_singleton()->multimesh_create());
	RenderingServer::get_singleton()->multimesh_set_mesh(multimesh, mesh);

	set_emitting(true);
	set_one_shot(false);
	set_amount(8);
	set_lifetime(1);
	set_fixed_fps(0);
	set_fractional_delta(true);
	set_pre_process_time(0);
	set_explosiveness_ratio(0);
	set_randomness_ratio(0);
	set_lifetime_randomness(0);
	set_use_local_coordinates(true);

	set_draw_order(DRAW_ORDER_INDEX);
	set_speed_scale(1);

	set_direction(Vector2(1, 0));
	set_spread(45);
	set_param(PARAM_INITIAL_LINEAR_VELOCITY, 0);
	set_param(PARAM_ANGULAR_VELOCITY, 0);
	set_param(PARAM_ORBIT_VELOCITY, 0);
	set_param(PARAM_LINEAR_ACCEL, 0);
	set_param(PARAM_RADIAL_ACCEL, 0);
	set_param(PARAM_TANGENTIAL_ACCEL, 0);
	set_param(PARAM_DAMPING, 0);
	set_param(PARAM_ANGLE, 0);
	set_param(PARAM_SCALE, 1);
	set_param(PARAM_HUE_VARIATION, 0);
	set_param(PARAM_ANIM_SPEED, 0);
	set_param(PARAM_ANIM_OFFSET, 0);
	set_emission_shape(EMISSION_SHAPE_POINT);
	set_emission_sphere_radius(1);
	set_emission_rect_extents(Vector2(1, 1));

	set_gravity(Vector2(0, 98));

	for (int i = 0; i < PARAM_MAX; i++) {
		set_param_randomness(Parameter(i), 0);
	}

	for (int i = 0; i < FLAG_MAX; i++) {
		flags[i] = false;
	}

	set_color(Color(1, 1, 1, 1));

	_update_mesh_texture();

	// CPUParticles2D defaults to interpolation off.
	// This is because the result often looks better when the particles are updated every frame.
	// Note that children will need to explicitly turn back on interpolation if they want to use it,
	// rather than relying on inherit mode.
	set_physics_interpolation_mode(Node::PHYSICS_INTERPOLATION_MODE_OFF);
}

CPUParticles2D::~CPUParticles2D() {
	RS::get_singleton()->free(multimesh);
	RS::get_singleton()->free(mesh);
}