/*************************************************************************/
/*  particle_system_sw.cpp                                               */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
/*                    http://www.godotengine.org                         */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur.                 */
/*                                                                       */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the       */
/* "Software"), to deal in the Software without restriction, including   */
/* without limitation the rights to use, copy, modify, merge, publish,   */
/* distribute, sublicense, and/or sell copies of the Software, and to    */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions:                                             */
/*                                                                       */
/* The above copyright notice and this permission notice shall be        */
/* included in all copies or substantial portions of the Software.       */
/*                                                                       */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
/*************************************************************************/
#include "particle_system_sw.h"
#include "sort.h"


ParticleSystemSW::ParticleSystemSW() {

	amount=8;
	emitting=true;

	for (int i=0;i<VS::PARTICLE_VAR_MAX;i++) {
		particle_randomness[i]=0.0;
	}

	particle_vars[VS::PARTICLE_LIFETIME]=2.0;//
	particle_vars[VS::PARTICLE_SPREAD]=0.2;//
	particle_vars[VS::PARTICLE_GRAVITY]=9.8;//
	particle_vars[VS::PARTICLE_LINEAR_VELOCITY]=0.2;//
	particle_vars[VS::PARTICLE_ANGULAR_VELOCITY]=0.0;//
	particle_vars[VS::PARTICLE_LINEAR_ACCELERATION]=0.0;//
	particle_vars[VS::PARTICLE_RADIAL_ACCELERATION]=0.0;//
	particle_vars[VS::PARTICLE_TANGENTIAL_ACCELERATION]=1.0;//
	particle_vars[VS::PARTICLE_DAMPING]=0.0;//
	particle_vars[VS::PARTICLE_INITIAL_SIZE]=1.0;
	particle_vars[VS::PARTICLE_FINAL_SIZE]=0.8;
	particle_vars[VS::PARTICLE_HEIGHT]=1;
	particle_vars[VS::PARTICLE_HEIGHT_SPEED_SCALE]=1;

	height_from_velocity=false;
	local_coordinates=false;

	particle_vars[VS::PARTICLE_INITIAL_ANGLE]=0.0;//

	gravity_normal=Vector3(0,-1.0,0);
	//emission_half_extents=Vector3(0.1,0.1,0.1);
	emission_half_extents=Vector3(1,1,1);
	color_phase_count=0;
	color_phases[0].pos=0.0;
	color_phases[0].color=Color(1.0,0.0,0.0);
	visibility_aabb=AABB(Vector3(-64,-64,-64),Vector3(128,128,128));

	attractor_count=0;

}


ParticleSystemSW::~ParticleSystemSW()
{
}


#define DEFAULT_SEED 1234567

_FORCE_INLINE_ static float _rand_from_seed(uint32_t *seed) {

	uint32_t k;
	uint32_t s = (*seed);
	if (s == 0)
		s = 0x12345987;
	k = s / 127773;
	s = 16807 * (s - k * 127773) - 2836 * k;
	if (s < 0)
		s += 2147483647;
	(*seed) = s;

	float v=((float)((*seed) & 0xFFFFF))/(float)0xFFFFF;
	v=v*2.0-1.0;
	return v;
}

_FORCE_INLINE_ static uint32_t _irand_from_seed(uint32_t *seed) {

	uint32_t k;
	uint32_t s = (*seed);
	if (s == 0)
		s = 0x12345987;
	k = s / 127773;
	s = 16807 * (s - k * 127773) - 2836 * k;
	if (s < 0)
		s += 2147483647;
	(*seed) = s;

	return s;
}

void ParticleSystemProcessSW::process(const ParticleSystemSW *p_system,const Transform& p_transform,float p_time) {

	valid=false;
	if (p_system->amount<=0) {
		ERR_EXPLAIN("Invalid amount of particles: "+itos(p_system->amount));
		ERR_FAIL_COND(p_system->amount<=0);
	}
	if (p_system->attractor_count<0 || p_system->attractor_count>VS::MAX_PARTICLE_ATTRACTORS) {
		ERR_EXPLAIN("Invalid amount of particle attractors.");
		ERR_FAIL_COND(p_system->attractor_count<0 || p_system->attractor_count>VS::MAX_PARTICLE_ATTRACTORS);
	}
	float lifetime = p_system->particle_vars[VS::PARTICLE_LIFETIME];
	if (lifetime<CMP_EPSILON) {
		ERR_EXPLAIN("Particle system lifetime too small.");
		ERR_FAIL_COND(lifetime<CMP_EPSILON);
	}
	valid=true;
	int particle_count=MIN(p_system->amount,ParticleSystemSW::MAX_PARTICLES);;


	int emission_point_count = p_system->emission_points.size();
	DVector<Vector3>::Read r;
	if (emission_point_count)
		r=p_system->emission_points.read();

	if (particle_count!=particle_data.size()) {

		//clear the whole system if particle amount changed
		particle_data.clear();
		particle_data.resize(p_system->amount);
		particle_system_time=0;
	}

	float next_time = particle_system_time+p_time;

	if (next_time > lifetime)
		next_time=Math::fmod(next_time,lifetime);


	ParticleData *pdata=&particle_data[0];
	Vector3 attractor_positions[VS::MAX_PARTICLE_ATTRACTORS];

	for(int i=0;i<p_system->attractor_count;i++) {

		attractor_positions[i]=p_transform.xform(p_system->attractors[i].pos);
	}


	for(int i=0;i<particle_count;i++) {

		ParticleData &p=pdata[i];

		float restart_time = (i * lifetime / p_system->amount);

		bool restart=false;

		if ( next_time < particle_system_time ) {

			if (restart_time > particle_system_time || restart_time < next_time )
				restart=true;

		} else if (restart_time > particle_system_time && restart_time < next_time ) {
			restart=true;
		}

		if (restart) {


			if (p_system->emitting) {
				if (emission_point_count==0) { //use AABB
					if (p_system->local_coordinates)
						p.pos = p_system->emission_half_extents * Vector3( _rand_from_seed(&rand_seed), _rand_from_seed(&rand_seed), _rand_from_seed(&rand_seed) );
					else
						p.pos = p_transform.xform( p_system->emission_half_extents * Vector3( _rand_from_seed(&rand_seed), _rand_from_seed(&rand_seed), _rand_from_seed(&rand_seed) ) );
				} else {
					//use preset positions
					if (p_system->local_coordinates)
						p.pos = r[_irand_from_seed(&rand_seed)%emission_point_count];
					else
						p.pos = p_transform.xform( r[_irand_from_seed(&rand_seed)%emission_point_count] );
				}


				float angle1 = _rand_from_seed(&rand_seed)*p_system->particle_vars[VS::PARTICLE_SPREAD]*Math_PI;
				float angle2 = _rand_from_seed(&rand_seed)*20.0*Math_PI; // make it more random like

				Vector3 rot_xz=Vector3( Math::sin(angle1), 0.0, Math::cos(angle1) );
				Vector3 rot = Vector3( Math::cos(angle2)*rot_xz.x,Math::sin(angle2)*rot_xz.x, rot_xz.z);

				p.vel=(rot*p_system->particle_vars[VS::PARTICLE_LINEAR_VELOCITY]+rot*p_system->particle_randomness[VS::PARTICLE_LINEAR_VELOCITY]*_rand_from_seed(&rand_seed));
				if (!p_system->local_coordinates)
					p.vel=p_transform.basis.xform( p.vel );

				p.vel+=p_system->emission_base_velocity;

				p.rot=p_system->particle_vars[VS::PARTICLE_INITIAL_ANGLE]+p_system->particle_randomness[VS::PARTICLE_INITIAL_ANGLE]*_rand_from_seed(&rand_seed);
				p.active=true;
				for(int r=0;r<PARTICLE_RANDOM_NUMBERS;r++)
					p.random[r]=_rand_from_seed(&rand_seed);

			} else {

				p.pos=Vector3();
				p.rot=0;
				p.vel=Vector3();
				p.active=false;
			}

		} else {

			if (!p.active)
				continue;

			Vector3 force;
			//apply gravity
			force=p_system->gravity_normal * (p_system->particle_vars[VS::PARTICLE_GRAVITY]+(p_system->particle_randomness[VS::PARTICLE_GRAVITY]*p.random[0]));
			//apply linear acceleration
			force+=p.vel.normalized() * (p_system->particle_vars[VS::PARTICLE_LINEAR_ACCELERATION]+p_system->particle_randomness[VS::PARTICLE_LINEAR_ACCELERATION]*p.random[1]);
			//apply radial acceleration
			Vector3 org;
			if (!p_system->local_coordinates)
				org=p_transform.origin;
			force+=(p.pos-org).normalized() * (p_system->particle_vars[VS::PARTICLE_RADIAL_ACCELERATION]+p_system->particle_randomness[VS::PARTICLE_RADIAL_ACCELERATION]*p.random[2]);
			//apply tangential acceleration
			force+=(p.pos-org).cross(p_system->gravity_normal).normalized() * (p_system->particle_vars[VS::PARTICLE_TANGENTIAL_ACCELERATION]+p_system->particle_randomness[VS::PARTICLE_TANGENTIAL_ACCELERATION]*p.random[3]);
			//apply attractor forces
			for(int a=0;a<p_system->attractor_count;a++) {

				force+=(p.pos-attractor_positions[a]).normalized() * p_system->attractors[a].force;
			}


			p.vel+=force * p_time;
			if (p_system->particle_vars[VS::PARTICLE_DAMPING]) {

				float v = p.vel.length();
				float damp = p_system->particle_vars[VS::PARTICLE_DAMPING] + p_system->particle_vars[VS::PARTICLE_DAMPING] * p_system->particle_randomness[VS::PARTICLE_DAMPING];
				v -= damp * p_time;
				if (v<0) {
					p.vel=Vector3();
				} else {
					p.vel=p.vel.normalized() * v;
				}

			}
			p.rot+=(p_system->particle_vars[VS::PARTICLE_ANGULAR_VELOCITY]+p_system->particle_randomness[VS::PARTICLE_ANGULAR_VELOCITY]*p.random[4]) *p_time;
			p.pos+=p.vel * p_time;
		}
	}

	particle_system_time=Math::fmod( particle_system_time+p_time, lifetime );


}

ParticleSystemProcessSW::ParticleSystemProcessSW() {

	particle_system_time=0;
	rand_seed=1234567;
	valid=false;
}


struct _ParticleSorterSW {


	_FORCE_INLINE_ bool operator()(const ParticleSystemDrawInfoSW::ParticleDrawInfo *p_a,const ParticleSystemDrawInfoSW::ParticleDrawInfo *p_b) const {

		return p_a->d > p_b->d; // draw from further away to closest
	}
};

void ParticleSystemDrawInfoSW::prepare(const ParticleSystemSW *p_system,const ParticleSystemProcessSW *p_process,const Transform& p_system_transform,const Transform& p_camera_transform) {

	ERR_FAIL_COND(p_process->particle_data.size() != p_system->amount);
	ERR_FAIL_COND(p_system->amount<=0 || p_system->amount>=ParticleSystemSW::MAX_PARTICLES);

	const ParticleSystemProcessSW::ParticleData *pdata=&p_process->particle_data[0];
	float time_pos=p_process->particle_system_time/p_system->particle_vars[VS::PARTICLE_LIFETIME];

	ParticleSystemSW::ColorPhase cphase[VS::MAX_PARTICLE_COLOR_PHASES];

	float last=-1;
	int col_count=0;

	for(int i=0;i<p_system->color_phase_count;i++) {

		if (p_system->color_phases[i].pos<=last)
			break;
		cphase[i]=p_system->color_phases[i];
		col_count++;
	}





	Vector3 camera_z_axis = p_camera_transform.basis.get_axis(2);

	for(int i=0;i<p_system->amount;i++) {

		ParticleDrawInfo &pdi=draw_info[i];
		pdi.data=&pdata[i];
		pdi.transform.origin=pdi.data->pos;
		if (p_system->local_coordinates)
			pdi.transform.origin=p_system_transform.xform(pdi.transform.origin);

		pdi.d=-camera_z_axis.dot(pdi.transform.origin);

		// adjust particle size, color and rotation

		float time = ((float)i / p_system->amount);
		if (time<time_pos)
			time=time_pos-time;
		else
			time=(1.0-time)+time_pos;

		Vector3 up=p_camera_transform.basis.get_axis(1); // up determines the rotation
		float up_scale=1.0;

		if (p_system->height_from_velocity) {

			Vector3 veld = pdi.data->vel;
			Vector3 cam_z = camera_z_axis.normalized();
			float vc = Math::abs(veld.normalized().dot(cam_z));

			if (vc<(1.0-CMP_EPSILON)) {
				up = Plane(cam_z,0).project(veld).normalized();
				float h = p_system->particle_vars[VS::PARTICLE_HEIGHT]+p_system->particle_randomness[VS::PARTICLE_HEIGHT]*pdi.data->random[7];
				float velh = veld.length();
				h+=velh*(p_system->particle_vars[VS::PARTICLE_HEIGHT_SPEED_SCALE]+p_system->particle_randomness[VS::PARTICLE_HEIGHT_SPEED_SCALE]*pdi.data->random[7]);


				up_scale=Math::lerp(1.0,h,(1.0-vc));
			}

		} else if (pdi.data->rot) {

			up.rotate(camera_z_axis,pdi.data->rot);
		}

		{
			// matrix
			Vector3 v_z = (p_camera_transform.origin-pdi.transform.origin).normalized();
//			Vector3 v_z = (p_camera_transform.origin-pdi.data->pos).normalized();
			Vector3 v_y = up;
			Vector3 v_x = v_y.cross(v_z);
			v_y = v_z.cross(v_x);
			v_x.normalize();
			v_y.normalize();


			float initial_scale, final_scale;
			initial_scale = p_system->particle_vars[VS::PARTICLE_INITIAL_SIZE]+p_system->particle_randomness[VS::PARTICLE_INITIAL_SIZE]*pdi.data->random[5];
			final_scale = p_system->particle_vars[VS::PARTICLE_FINAL_SIZE]+p_system->particle_randomness[VS::PARTICLE_FINAL_SIZE]*pdi.data->random[6];
			float scale = initial_scale + time * (final_scale - initial_scale);

			pdi.transform.basis.set_axis(0,v_x * scale);
			pdi.transform.basis.set_axis(1,v_y * scale * up_scale);
			pdi.transform.basis.set_axis(2,v_z * scale);
		}



		int cpos=0;

		while(cpos<col_count) {

			if (cphase[cpos].pos > time)
				break;
			cpos++;
		}

		cpos--;


		if (cpos==-1)
			pdi.color=Color(1,1,1,1);
		else {
			if (cpos==col_count-1)
				pdi.color=cphase[cpos].color;
			else {
				float diff = (cphase[cpos+1].pos-cphase[cpos].pos);
				if (diff>0)
					pdi.color=cphase[cpos].color.linear_interpolate(cphase[cpos+1].color, (time - cphase[cpos].pos) / diff );
				else
					pdi.color=cphase[cpos+1].color;
			}
		}


		draw_info_order[i]=&pdi;

	}


	SortArray<ParticleDrawInfo*,_ParticleSorterSW> particle_sort;
	particle_sort.sort(&draw_info_order[0],p_system->amount);

}