effect.c

Go to the documentation of this file.

/*  effect.c
 * 
 * 
 * $Id: effect.c 38663 2011-07-24 17:44:22Z jhk $
 *
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): none yet.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#include <stddef.h>
#include "BLI_storage.h" /* _LARGEFILE_SOURCE */

#include <math.h>
#include <stdlib.h>

#include "MEM_guardedalloc.h"

#include "DNA_curve_types.h"
#include "DNA_effect_types.h"
#include "DNA_group_types.h"
#include "DNA_ipo_types.h"
#include "DNA_key_types.h"
#include "DNA_lattice_types.h"
#include "DNA_listBase.h"
#include "DNA_mesh_types.h"
#include "DNA_meshdata_types.h"
#include "DNA_material_types.h"
#include "DNA_object_types.h"
#include "DNA_object_force.h"
#include "DNA_particle_types.h"
#include "DNA_texture_types.h"
#include "DNA_scene_types.h"

#include "BLI_math.h"
#include "BLI_blenlib.h"
#include "BLI_jitter.h"
#include "BLI_listbase.h"
#include "BLI_noise.h"
#include "BLI_rand.h"
#include "BLI_utildefines.h"

#include "PIL_time.h"

#include "BKE_action.h"
#include "BKE_anim.h"           /* needed for where_on_path */
#include "BKE_armature.h"
#include "BKE_blender.h"
#include "BKE_collision.h"
#include "BKE_constraint.h"
#include "BKE_deform.h"
#include "BKE_depsgraph.h"
#include "BKE_displist.h"
#include "BKE_DerivedMesh.h"
#include "BKE_cdderivedmesh.h"
#include "BKE_effect.h"
#include "BKE_global.h"
#include "BKE_group.h"
#include "BKE_ipo.h"
#include "BKE_key.h"
#include "BKE_lattice.h"
#include "BKE_mesh.h"
#include "BKE_material.h"
#include "BKE_main.h"
#include "BKE_modifier.h"
#include "BKE_object.h"
#include "BKE_particle.h"
#include "BKE_scene.h"


#include "RE_render_ext.h"
#include "RE_shader_ext.h"

/* fluid sim particle import */
#ifndef DISABLE_ELBEEM
#include "DNA_object_fluidsim.h"
#include "LBM_fluidsim.h"
#include <zlib.h>
#include <string.h>
#endif // DISABLE_ELBEEM

//XXX #include "BIF_screen.h"

EffectorWeights *BKE_add_effector_weights(Group *group)
{
        EffectorWeights *weights = MEM_callocN(sizeof(EffectorWeights), "EffectorWeights");
        int i;

        for(i=0; i<NUM_PFIELD_TYPES; i++)
                weights->weight[i] = 1.0f;

        weights->global_gravity = 1.0f;

        weights->group = group;

        return weights;
}
PartDeflect *object_add_collision_fields(int type)
{
        PartDeflect *pd;

        pd= MEM_callocN(sizeof(PartDeflect), "PartDeflect");

        pd->forcefield = type;
        pd->pdef_sbdamp = 0.1f;
        pd->pdef_sbift  = 0.2f;
        pd->pdef_sboft  = 0.02f;
        pd->seed = ((unsigned int)(ceil(PIL_check_seconds_timer()))+1) % 128;
        pd->f_strength = 1.0f;
        pd->f_damp = 1.0f;

        /* set sensible defaults based on type */
        switch(type) {
                case PFIELD_VORTEX:
                        pd->shape = PFIELD_SHAPE_PLANE;
                        break;
                case PFIELD_WIND:
                        pd->shape = PFIELD_SHAPE_PLANE;
                        pd->f_flow = 1.0f; /* realistic wind behavior */
                        break;
                case PFIELD_TEXTURE:
                        pd->f_size = 1.0f;
                        break;
        }
        pd->flag = PFIELD_DO_LOCATION|PFIELD_DO_ROTATION;

        return pd;
}

/* temporal struct, used for reading return of mesh_get_mapped_verts_nors() */

typedef struct VeNoCo {
        float co[3], no[3];
} VeNoCo;

/* ***************** PARTICLES ***************** */

/* deprecated, only keep this for readfile.c */
PartEff *give_parteff(Object *ob)
{
        PartEff *paf;
        
        paf= ob->effect.first;
        while(paf) {
                if(paf->type==EFF_PARTICLE) return paf;
                paf= paf->next;
        }
        return NULL;
}

void free_effect(Effect *eff)
{
        PartEff *paf;
        
        if(eff->type==EFF_PARTICLE) {
                paf= (PartEff *)eff;
                if(paf->keys) MEM_freeN(paf->keys);
        }
        MEM_freeN(eff); 
}


void free_effects(ListBase *lb)
{
        Effect *eff;
        
        eff= lb->first;
        while(eff) {
                BLI_remlink(lb, eff);
                free_effect(eff);
                eff= lb->first;
        }
}

/* -------------------------- Effectors ------------------ */
void free_partdeflect(PartDeflect *pd)
{
        if(!pd)
                return;

        if(pd->tex)
                pd->tex->id.us--;

        if(pd->rng)
                rng_free(pd->rng);

        MEM_freeN(pd);
}

static void precalculate_effector(EffectorCache *eff)
{
        unsigned int cfra = (unsigned int)(eff->scene->r.cfra >= 0 ? eff->scene->r.cfra : -eff->scene->r.cfra);
        if(!eff->pd->rng)
                eff->pd->rng = rng_new(eff->pd->seed + cfra);
        else
                rng_srandom(eff->pd->rng, eff->pd->seed + cfra);

        if(eff->pd->forcefield == PFIELD_GUIDE && eff->ob->type==OB_CURVE) {
                Curve *cu= eff->ob->data;
                if(cu->flag & CU_PATH) {
                        if(cu->path==NULL || cu->path->data==NULL)
                                makeDispListCurveTypes(eff->scene, eff->ob, 0);

                        if(cu->path && cu->path->data) {
                                where_on_path(eff->ob, 0.0, eff->guide_loc, eff->guide_dir, NULL, &eff->guide_radius, NULL);
                                mul_m4_v3(eff->ob->obmat, eff->guide_loc);
                                mul_mat3_m4_v3(eff->ob->obmat, eff->guide_dir);
                        }
                }
        }
        else if(eff->pd->shape == PFIELD_SHAPE_SURFACE) {
                eff->surmd = (SurfaceModifierData *)modifiers_findByType ( eff->ob, eModifierType_Surface );
                if(eff->ob->type == OB_CURVE)
                        eff->flag |= PE_USE_NORMAL_DATA;
        }
        else if(eff->psys)
                psys_update_particle_tree(eff->psys, eff->scene->r.cfra);

        /* Store object velocity */
        if(eff->ob) {
                float old_vel[3];

                where_is_object_time(eff->scene, eff->ob, cfra - 1.0f);
                copy_v3_v3(old_vel, eff->ob->obmat[3]); 
                where_is_object_time(eff->scene, eff->ob, cfra);
                sub_v3_v3v3(eff->velocity, eff->ob->obmat[3], old_vel);
        }
}
static EffectorCache *new_effector_cache(Scene *scene, Object *ob, ParticleSystem *psys, PartDeflect *pd)
{
        EffectorCache *eff = MEM_callocN(sizeof(EffectorCache), "EffectorCache");
        eff->scene = scene;
        eff->ob = ob;
        eff->psys = psys;
        eff->pd = pd;
        eff->frame = -1;

        precalculate_effector(eff);

        return eff;
}
static void add_object_to_effectors(ListBase **effectors, Scene *scene, EffectorWeights *weights, Object *ob, Object *ob_src)
{
        EffectorCache *eff = NULL;

        if( ob == ob_src || weights->weight[ob->pd->forcefield] == 0.0f )
                return;

        if (ob->pd->shape == PFIELD_SHAPE_POINTS && !ob->derivedFinal )
                return;

        if(*effectors == NULL)
                *effectors = MEM_callocN(sizeof(ListBase), "effectors list");

        eff = new_effector_cache(scene, ob, NULL, ob->pd);

        /* make sure imat is up to date */
        invert_m4_m4(ob->imat, ob->obmat);

        BLI_addtail(*effectors, eff);
}
static void add_particles_to_effectors(ListBase **effectors, Scene *scene, EffectorWeights *weights, Object *ob, ParticleSystem *psys, ParticleSystem *psys_src)
{
        ParticleSettings *part= psys->part;

        if( !psys_check_enabled(ob, psys) )
                return;

        if( psys == psys_src && (part->flag & PART_SELF_EFFECT) == 0)
                return;

        if( part->pd && part->pd->forcefield && weights->weight[part->pd->forcefield] != 0.0f) {
                if(*effectors == NULL)
                        *effectors = MEM_callocN(sizeof(ListBase), "effectors list");

                BLI_addtail(*effectors, new_effector_cache(scene, ob, psys, part->pd));
        }

        if (part->pd2 && part->pd2->forcefield && weights->weight[part->pd2->forcefield] != 0.0f) {
                if(*effectors == NULL)
                        *effectors = MEM_callocN(sizeof(ListBase), "effectors list");

                BLI_addtail(*effectors, new_effector_cache(scene, ob, psys, part->pd2));
        }
}

/* returns ListBase handle with objects taking part in the effecting */
ListBase *pdInitEffectors(Scene *scene, Object *ob_src, ParticleSystem *psys_src, EffectorWeights *weights)
{
        Base *base;
        unsigned int layer= ob_src->lay;
        ListBase *effectors = NULL;
        
        if(weights->group) {
                GroupObject *go;
                
                for(go= weights->group->gobject.first; go; go= go->next) {
                        if( (go->ob->lay & layer) ) {
                                if( go->ob->pd && go->ob->pd->forcefield )
                                        add_object_to_effectors(&effectors, scene, weights, go->ob, ob_src);

                                if( go->ob->particlesystem.first ) {
                                        ParticleSystem *psys= go->ob->particlesystem.first;

                                        for( ; psys; psys=psys->next )
                                                add_particles_to_effectors(&effectors, scene, weights, go->ob, psys, psys_src);
                                }
                        }
                }
        }
        else {
                for(base = scene->base.first; base; base= base->next) {
                        if( (base->lay & layer) ) {
                                if( base->object->pd && base->object->pd->forcefield )
                                add_object_to_effectors(&effectors, scene, weights, base->object, ob_src);

                                if( base->object->particlesystem.first ) {
                                        ParticleSystem *psys= base->object->particlesystem.first;

                                        for( ; psys; psys=psys->next )
                                                add_particles_to_effectors(&effectors, scene, weights, base->object, psys, psys_src);
                                }
                        }
                }
        }
        return effectors;
}

void pdEndEffectors(ListBase **effectors)
{
        if(*effectors) {
                EffectorCache *eff = (*effectors)->first;

                for(; eff; eff=eff->next) {
                        if(eff->guide_data)
                                MEM_freeN(eff->guide_data);
                }

                BLI_freelistN(*effectors);
                MEM_freeN(*effectors);
                *effectors = NULL;
        }
}


void pd_point_from_particle(ParticleSimulationData *sim, ParticleData *pa, ParticleKey *state, EffectedPoint *point)
{
        ParticleSettings *part = sim->psys->part;
        point->loc = state->co;
        point->vel = state->vel;
        point->index = pa - sim->psys->particles;
        point->size = pa->size;
        point->charge = 0.0f;
        
        if(part->pd && part->pd->forcefield == PFIELD_CHARGE)
                point->charge += part->pd->f_strength;

        if(part->pd2 && part->pd2->forcefield == PFIELD_CHARGE)
                point->charge += part->pd2->f_strength;

        point->vel_to_sec = 1.0f;
        point->vel_to_frame = psys_get_timestep(sim);

        point->flag = 0;

        if(sim->psys->part->flag & PART_ROT_DYN) {
                point->ave = state->ave;
                point->rot = state->rot;
        }
        else
                point->ave = point->rot = NULL;

        point->psys = sim->psys;
}

void pd_point_from_loc(Scene *scene, float *loc, float *vel, int index, EffectedPoint *point)
{
        point->loc = loc;
        point->vel = vel;
        point->index = index;
        point->size = 0.0f;

        point->vel_to_sec = (float)scene->r.frs_sec;
        point->vel_to_frame = 1.0f;

        point->flag = 0;

        point->ave = point->rot = NULL;
        point->psys = NULL;
}
void pd_point_from_soft(Scene *scene, float *loc, float *vel, int index, EffectedPoint *point)
{
        point->loc = loc;
        point->vel = vel;
        point->index = index;
        point->size = 0.0f;

        point->vel_to_sec = (float)scene->r.frs_sec;
        point->vel_to_frame = 1.0f;

        point->flag = PE_WIND_AS_SPEED;

        point->ave = point->rot = NULL;

        point->psys = NULL;
}
/************************************************/
/*                      Effectors               */
/************************************************/

// triangle - ray callback function
static void eff_tri_ray_hit(void *UNUSED(userData), int UNUSED(index), const BVHTreeRay *UNUSED(ray), BVHTreeRayHit *hit)
{       
        // whenever we hit a bounding box, we don't check further
        hit->dist = -1;
        hit->index = 1;
}

// get visibility of a wind ray
static float eff_calc_visibility(ListBase *colliders, EffectorCache *eff, EffectorData *efd, EffectedPoint *point)
{
        ListBase *colls = colliders;
        ColliderCache *col;
        float norm[3], len = 0.0;
        float visibility = 1.0, absorption = 0.0;
        
        if(!(eff->pd->flag & PFIELD_VISIBILITY))
                return visibility;

        if(!colls)
                colls = get_collider_cache(eff->scene, eff->ob, NULL);

        if(!colls)
                return visibility;

        negate_v3_v3(norm, efd->vec_to_point);
        len = normalize_v3(norm);
        
        // check all collision objects
        for(col = colls->first; col; col = col->next)
        {
                CollisionModifierData *collmd = col->collmd;

                if(col->ob == eff->ob)
                        continue;
                
                if(collmd->bvhtree)
                {
                        BVHTreeRayHit hit;
                        
                        hit.index = -1;
                        hit.dist = len + FLT_EPSILON;
                        
                        // check if the way is blocked
                        if(BLI_bvhtree_ray_cast(collmd->bvhtree, point->loc, norm, 0.0f, &hit, eff_tri_ray_hit, NULL)>=0)
                        {
                                absorption= col->ob->pd->absorption;

                                // visibility is only between 0 and 1, calculated from 1-absorption
                                visibility *= CLAMPIS(1.0f-absorption, 0.0f, 1.0f);
                                
                                if(visibility <= 0.0f)
                                        break;
                        }
                }
        }

        if(!colliders)
                free_collider_cache(&colls);
        
        return visibility;
}

// noise function for wind e.g.
static float wind_func(struct RNG *rng, float strength)
{
        int random = (rng_getInt(rng)+1) % 128; // max 2357
        float force = rng_getFloat(rng) + 1.0f;
        float ret;
        float sign = 0;
        
        sign = ((float)random > 64.0f) ? 1.0f: -1.0f; // dividing by 2 is not giving equal sign distribution
        
        ret = sign*((float)random / force)*strength/128.0f;
        
        return ret;
}

/* maxdist: zero effect from this distance outwards (if usemax) */
/* mindist: full effect up to this distance (if usemin) */
/* power: falloff with formula 1/r^power */
static float falloff_func(float fac, int usemin, float mindist, int usemax, float maxdist, float power)
{
        /* first quick checks */
        if(usemax && fac > maxdist)
                return 0.0f;

        if(usemin && fac < mindist)
                return 1.0f;

        if(!usemin)
                mindist = 0.0;

        return pow((double)(1.0f+fac-mindist), (double)(-power));
}

static float falloff_func_dist(PartDeflect *pd, float fac)
{
        return falloff_func(fac, pd->flag&PFIELD_USEMIN, pd->mindist, pd->flag&PFIELD_USEMAX, pd->maxdist, pd->f_power);
}

static float falloff_func_rad(PartDeflect *pd, float fac)
{
        return falloff_func(fac, pd->flag&PFIELD_USEMINR, pd->minrad, pd->flag&PFIELD_USEMAXR, pd->maxrad, pd->f_power_r);
}

float effector_falloff(EffectorCache *eff, EffectorData *efd, EffectedPoint *UNUSED(point), EffectorWeights *weights)
{
        float temp[3];
        float falloff = weights ? weights->weight[0] * weights->weight[eff->pd->forcefield] : 1.0f;
        float fac, r_fac;

        fac = dot_v3v3(efd->nor, efd->vec_to_point2);

        if(eff->pd->zdir == PFIELD_Z_POS && fac < 0.0f)
                falloff=0.0f;
        else if(eff->pd->zdir == PFIELD_Z_NEG && fac > 0.0f)
                falloff=0.0f;
        else switch(eff->pd->falloff){
                case PFIELD_FALL_SPHERE:
                        falloff*= falloff_func_dist(eff->pd, efd->distance);
                        break;

                case PFIELD_FALL_TUBE:
                        falloff*= falloff_func_dist(eff->pd, ABS(fac));
                        if(falloff == 0.0f)
                                break;

                        VECADDFAC(temp, efd->vec_to_point, efd->nor, -fac);
                        r_fac= len_v3(temp);
                        falloff*= falloff_func_rad(eff->pd, r_fac);
                        break;
                case PFIELD_FALL_CONE:
                        falloff*= falloff_func_dist(eff->pd, ABS(fac));
                        if(falloff == 0.0f)
                                break;

                        r_fac=saacos(fac/len_v3(efd->vec_to_point))*180.0f/(float)M_PI;
                        falloff*= falloff_func_rad(eff->pd, r_fac);

                        break;
        }

        return falloff;
}

int closest_point_on_surface(SurfaceModifierData *surmd, float *co, float *surface_co, float *surface_nor, float *surface_vel)
{
        BVHTreeNearest nearest;

        nearest.index = -1;
        nearest.dist = FLT_MAX;

        BLI_bvhtree_find_nearest(surmd->bvhtree->tree, co, &nearest, surmd->bvhtree->nearest_callback, surmd->bvhtree);

        if(nearest.index != -1) {
                VECCOPY(surface_co, nearest.co);

                if(surface_nor) {
                        VECCOPY(surface_nor, nearest.no);
                }

                if(surface_vel) {
                        MFace *mface = CDDM_get_face(surmd->dm, nearest.index);
                        
                        VECCOPY(surface_vel, surmd->v[mface->v1].co);
                        add_v3_v3(surface_vel, surmd->v[mface->v2].co);
                        add_v3_v3(surface_vel, surmd->v[mface->v3].co);
                        if(mface->v4)
                                add_v3_v3(surface_vel, surmd->v[mface->v4].co);

                        mul_v3_fl(surface_vel, mface->v4 ? 0.25f : 0.333f);
                }
                return 1;
        }

        return 0;
}
int get_effector_data(EffectorCache *eff, EffectorData *efd, EffectedPoint *point, int real_velocity)
{
        float cfra = eff->scene->r.cfra;
        int ret = 0;

        if(eff->pd && eff->pd->shape==PFIELD_SHAPE_SURFACE && eff->surmd) {
                /* closest point in the object surface is an effector */
                float vec[3];

                /* using velocity corrected location allows for easier sliding over effector surface */
                copy_v3_v3(vec, point->vel);
                mul_v3_fl(vec, point->vel_to_frame);
                add_v3_v3(vec, point->loc);

                ret = closest_point_on_surface(eff->surmd, vec, efd->loc, efd->nor, real_velocity ? efd->vel : NULL);

                efd->size = 0.0f;
        }
        else if(eff->pd && eff->pd->shape==PFIELD_SHAPE_POINTS) {

                if(eff->ob->derivedFinal) {
                        DerivedMesh *dm = eff->ob->derivedFinal;

                        dm->getVertCo(dm, *efd->index, efd->loc);
                        dm->getVertNo(dm, *efd->index, efd->nor);

                        mul_m4_v3(eff->ob->obmat, efd->loc);
                        mul_mat3_m4_v3(eff->ob->obmat, efd->nor);

                        normalize_v3(efd->nor);

                        efd->size = 0.0f;

                        
                        ret = 1;
                }
        }
        else if(eff->psys) {
                ParticleData *pa = eff->psys->particles + *efd->index;
                ParticleKey state;

                /* exclude the particle itself for self effecting particles */
                if(eff->psys == point->psys && *efd->index == point->index)
                        ;
                else {
                        ParticleSimulationData sim= {NULL};
                        sim.scene= eff->scene;
                        sim.ob= eff->ob;
                        sim.psys= eff->psys;

                        /* TODO: time from actual previous calculated frame (step might not be 1) */
                        state.time = cfra - 1.0f;
                        ret = psys_get_particle_state(&sim, *efd->index, &state, 0);

                        /* TODO */
                        //if(eff->pd->forcefiled == PFIELD_HARMONIC && ret==0) {
                        //      if(pa->dietime < eff->psys->cfra)
                        //              eff->flag |= PE_VELOCITY_TO_IMPULSE;
                        //}

                        copy_v3_v3(efd->loc, state.co);

                        /* rather than use the velocity use rotated x-axis (defaults to velocity) */
                        efd->nor[0] = 1.f;
                        efd->nor[1] = efd->nor[2] = 0.f;
                        mul_qt_v3(state.rot, efd->nor);
                
                        if(real_velocity)
                                copy_v3_v3(efd->vel, state.vel);

                        efd->size = pa->size;
                }
        }
        else {
                /* use center of object for distance calculus */
                Object *ob = eff->ob;
                Object obcopy = *ob;

                /* use z-axis as normal*/
                normalize_v3_v3(efd->nor, ob->obmat[2]);

                if(eff->pd && eff->pd->shape == PFIELD_SHAPE_PLANE) {
                        float temp[3], translate[3];
                        sub_v3_v3v3(temp, point->loc, ob->obmat[3]);
                        project_v3_v3v3(translate, temp, efd->nor);

                        /* for vortex the shape chooses between old / new force */
                        if(eff->pd->forcefield == PFIELD_VORTEX)
                                add_v3_v3v3(efd->loc, ob->obmat[3], translate);
                        else /* normally efd->loc is closest point on effector xy-plane */
                                sub_v3_v3v3(efd->loc, point->loc, translate);
                }
                else {
                        VECCOPY(efd->loc, ob->obmat[3]);
                }

                if(real_velocity)
                        copy_v3_v3(efd->vel, eff->velocity);

                *eff->ob = obcopy;

                efd->size = 0.0f;

                ret = 1;
        }

        if(ret) {
                sub_v3_v3v3(efd->vec_to_point, point->loc, efd->loc);
                efd->distance = len_v3(efd->vec_to_point);

                /* rest length for harmonic effector, will have to see later if this could be extended to other effectors */
                if(eff->pd && eff->pd->forcefield == PFIELD_HARMONIC && eff->pd->f_size)
                        mul_v3_fl(efd->vec_to_point, (efd->distance-eff->pd->f_size)/efd->distance);

                if(eff->flag & PE_USE_NORMAL_DATA) {
                        VECCOPY(efd->vec_to_point2, efd->vec_to_point);
                        VECCOPY(efd->nor2, efd->nor);
                }
                else {
                        /* for some effectors we need the object center every time */
                        sub_v3_v3v3(efd->vec_to_point2, point->loc, eff->ob->obmat[3]);
                        normalize_v3_v3(efd->nor2, eff->ob->obmat[2]);
                }
        }

        return ret;
}
static void get_effector_tot(EffectorCache *eff, EffectorData *efd, EffectedPoint *point, int *tot, int *p, int *step)
{
        if(eff->pd->shape == PFIELD_SHAPE_POINTS) {
                efd->index = p;

                *p = 0;
                *tot = eff->ob->derivedFinal ? eff->ob->derivedFinal->numVertData : 1;

                if(*tot && eff->pd->forcefield == PFIELD_HARMONIC && point->index >= 0) {
                        *p = point->index % *tot;
                        *tot = *p+1;
                }
        }
        else if(eff->psys) {
                efd->index = p;

                *p = 0;
                *tot = eff->psys->totpart;
                
                if(eff->pd->forcefield == PFIELD_CHARGE) {
                        /* Only the charge of the effected particle is used for 
                        interaction, not fall-offs. If the fall-offs aren't the 
                        same this will be unphysical, but for animation this            
                        could be the wanted behavior. If you want physical
                        correctness the fall-off should be spherical 2.0 anyways.
                        */
                        efd->charge = eff->pd->f_strength;
                }
                else if(eff->pd->forcefield == PFIELD_HARMONIC && (eff->pd->flag & PFIELD_MULTIPLE_SPRINGS)==0) {
                        /* every particle is mapped to only one harmonic effector particle */
                        *p= point->index % eff->psys->totpart;
                        *tot= *p + 1;
                }

                if(eff->psys->part->effector_amount) {
                        int totpart = eff->psys->totpart;
                        int amount = eff->psys->part->effector_amount;

                        *step = (totpart > amount) ? totpart/amount : 1;
                }
        }
        else {
                *p = 0;
                *tot = 1;
        }
}
static void do_texture_effector(EffectorCache *eff, EffectorData *efd, EffectedPoint *point, float *total_force)
{
        TexResult result[4];
        float tex_co[3], strength, force[3];
        float nabla = eff->pd->tex_nabla;
        int hasrgb;
        short mode = eff->pd->tex_mode;

        if(!eff->pd->tex)
                return;

        result[0].nor = result[1].nor = result[2].nor = result[3].nor = NULL;

        strength= eff->pd->f_strength * efd->falloff;

        VECCOPY(tex_co,point->loc);

        if(eff->pd->flag & PFIELD_TEX_2D) {
                float fac=-dot_v3v3(tex_co, efd->nor);
                VECADDFAC(tex_co, tex_co, efd->nor, fac);
        }

        if(eff->pd->flag & PFIELD_TEX_OBJECT) {
                mul_m4_v3(eff->ob->imat, tex_co);
        }

        hasrgb = multitex_ext(eff->pd->tex, tex_co, NULL,NULL, 0, result);

        if(hasrgb && mode==PFIELD_TEX_RGB) {
                force[0] = (0.5f - result->tr) * strength;
                force[1] = (0.5f - result->tg) * strength;
                force[2] = (0.5f - result->tb) * strength;
        }
        else {
                strength/=nabla;

                tex_co[0] += nabla;
                multitex_ext(eff->pd->tex, tex_co, NULL, NULL, 0, result+1);

                tex_co[0] -= nabla;
                tex_co[1] += nabla;
                multitex_ext(eff->pd->tex, tex_co, NULL, NULL, 0, result+2);

                tex_co[1] -= nabla;
                tex_co[2] += nabla;
                multitex_ext(eff->pd->tex, tex_co, NULL, NULL, 0, result+3);

                if(mode == PFIELD_TEX_GRAD || !hasrgb) { /* if we dont have rgb fall back to grad */
                        force[0] = (result[0].tin - result[1].tin) * strength;
                        force[1] = (result[0].tin - result[2].tin) * strength;
                        force[2] = (result[0].tin - result[3].tin) * strength;
                }
                else { /*PFIELD_TEX_CURL*/
                        float dbdy, dgdz, drdz, dbdx, dgdx, drdy;

                        dbdy = result[2].tb - result[0].tb;
                        dgdz = result[3].tg - result[0].tg;
                        drdz = result[3].tr - result[0].tr;
                        dbdx = result[1].tb - result[0].tb;
                        dgdx = result[1].tg - result[0].tg;
                        drdy = result[2].tr - result[0].tr;

                        force[0] = (dbdy - dgdz) * strength;
                        force[1] = (drdz - dbdx) * strength;
                        force[2] = (dgdx - drdy) * strength;
                }
        }

        if(eff->pd->flag & PFIELD_TEX_2D){
                float fac = -dot_v3v3(force, efd->nor);
                VECADDFAC(force, force, efd->nor, fac);
        }

        add_v3_v3(total_force, force);
}
static void do_physical_effector(EffectorCache *eff, EffectorData *efd, EffectedPoint *point, float *total_force)
{
        PartDeflect *pd = eff->pd;
        RNG *rng = pd->rng;
        float force[3]={0,0,0};
        float temp[3];
        float fac;
        float strength = pd->f_strength;
        float damp = pd->f_damp;
        float noise_factor = pd->f_noise;

        if(noise_factor > 0.0f) {
                strength += wind_func(rng, noise_factor);

                if(ELEM(pd->forcefield, PFIELD_HARMONIC, PFIELD_DRAG))
                        damp += wind_func(rng, noise_factor);
        }

        VECCOPY(force, efd->vec_to_point);

        switch(pd->forcefield){
                case PFIELD_WIND:
                        VECCOPY(force, efd->nor);
                        mul_v3_fl(force, strength * efd->falloff);
                        break;
                case PFIELD_FORCE:
                        normalize_v3(force);
                        mul_v3_fl(force, strength * efd->falloff);
                        break;
                case PFIELD_VORTEX:
                        /* old vortex force */
                        if(pd->shape == PFIELD_SHAPE_POINT) {
                                cross_v3_v3v3(force, efd->nor, efd->vec_to_point);
                                normalize_v3(force);
                                mul_v3_fl(force, strength * efd->distance * efd->falloff);
                        }
                        else {
                                /* new vortex force */
                                cross_v3_v3v3(temp, efd->nor2, efd->vec_to_point2);
                                mul_v3_fl(temp, strength * efd->falloff);
                                
                                cross_v3_v3v3(force, efd->nor2, temp);
                                mul_v3_fl(force, strength * efd->falloff);
                                
                                VECADDFAC(temp, temp, point->vel, -point->vel_to_sec);
                                add_v3_v3(force, temp);
                        }
                        break;
                case PFIELD_MAGNET:
                        if(eff->pd->shape == PFIELD_SHAPE_POINT)
                                /* magnetic field of a moving charge */
                                cross_v3_v3v3(temp, efd->nor, efd->vec_to_point);
                        else
                                copy_v3_v3(temp, efd->nor);

                        normalize_v3(temp);
                        mul_v3_fl(temp, strength * efd->falloff);
                        cross_v3_v3v3(force, point->vel, temp);
                        mul_v3_fl(force, point->vel_to_sec);
                        break;
                case PFIELD_HARMONIC:
                        mul_v3_fl(force, -strength * efd->falloff);
                        copy_v3_v3(temp, point->vel);
                        mul_v3_fl(temp, -damp * 2.0f * (float)sqrt(fabs(strength)) * point->vel_to_sec);
                        add_v3_v3(force, temp);
                        break;
                case PFIELD_CHARGE:
                        mul_v3_fl(force, point->charge * strength * efd->falloff);
                        break;
                case PFIELD_LENNARDJ:
                        fac = pow((efd->size + point->size) / efd->distance, 6.0);
                        
                        fac = - fac * (1.0f - fac) / efd->distance;

                        /* limit the repulsive term drastically to avoid huge forces */
                        fac = ((fac>2.0f) ? 2.0f : fac);

                        mul_v3_fl(force, strength * fac);
                        break;
                case PFIELD_BOID:
                        /* Boid field is handled completely in boids code. */
                        return;
                case PFIELD_TURBULENCE:
                        if(pd->flag & PFIELD_GLOBAL_CO) {
                                VECCOPY(temp, point->loc);
                        }
                        else {
                                VECADD(temp, efd->vec_to_point2, efd->nor2);
                        }
                        force[0] = -1.0f + 2.0f * BLI_gTurbulence(pd->f_size, temp[0], temp[1], temp[2], 2,0,2);
                        force[1] = -1.0f + 2.0f * BLI_gTurbulence(pd->f_size, temp[1], temp[2], temp[0], 2,0,2);
                        force[2] = -1.0f + 2.0f * BLI_gTurbulence(pd->f_size, temp[2], temp[0], temp[1], 2,0,2);
                        mul_v3_fl(force, strength * efd->falloff);
                        break;
                case PFIELD_DRAG:
                        VECCOPY(force, point->vel);
                        fac = normalize_v3(force) * point->vel_to_sec;

                        strength = MIN2(strength, 2.0f);
                        damp = MIN2(damp, 2.0f);

                        mul_v3_fl(force, -efd->falloff * fac * (strength * fac + damp));
                        break;
        }

        if(pd->flag & PFIELD_DO_LOCATION) {
                VECADDFAC(total_force, total_force, force, 1.0f/point->vel_to_sec);

                if(ELEM(pd->forcefield, PFIELD_HARMONIC, PFIELD_DRAG)==0 && pd->f_flow != 0.0f) {
                        VECADDFAC(total_force, total_force, point->vel, -pd->f_flow * efd->falloff);
                }
        }

        if(pd->flag & PFIELD_DO_ROTATION && point->ave && point->rot) {
                float xvec[3] = {1.0f, 0.0f, 0.0f};
                float dave[3];
                mul_qt_v3(point->rot, xvec);
                cross_v3_v3v3(dave, xvec, force);
                if(pd->f_flow != 0.0f) {
                        VECADDFAC(dave, dave, point->ave, -pd->f_flow * efd->falloff);
                }
                add_v3_v3(point->ave, dave);
        }
}

/*  -------- pdDoEffectors() --------
        generic force/speed system, now used for particles and softbodies
        scene       = scene where it runs in, for time and stuff
        lb                      = listbase with objects that take part in effecting
        opco            = global coord, as input
        force           = force accumulator
        speed           = actual current speed which can be altered
        cur_time        = "external" time in frames, is constant for static particles
        loc_time        = "local" time in frames, range <0-1> for the lifetime of particle
        par_layer       = layer the caller is in
        flags           = only used for softbody wind now
        guide           = old speed of particle

*/
void pdDoEffectors(ListBase *effectors, ListBase *colliders, EffectorWeights *weights, EffectedPoint *point, float *force, float *impulse)
{
/*
        Modifies the force on a particle according to its
        relation with the effector object
        Different kind of effectors include:
                Forcefields: Gravity-like attractor
                (force power is related to the inverse of distance to the power of a falloff value)
                Vortex fields: swirling effectors
                (particles rotate around Z-axis of the object. otherwise, same relation as)
                (Forcefields, but this is not done through a force/acceleration)
                Guide: particles on a path
                (particles are guided along a curve bezier or old nurbs)
                (is independent of other effectors)
*/
        EffectorCache *eff;
        EffectorData efd;
        int p=0, tot = 1, step = 1;

        /* Cycle through collected objects, get total of (1/(gravity_strength * dist^gravity_power)) */
        /* Check for min distance here? (yes would be cool to add that, ton) */
        
        if(effectors) for(eff = effectors->first; eff; eff=eff->next) {
                /* object effectors were fully checked to be OK to evaluate! */

                get_effector_tot(eff, &efd, point, &tot, &p, &step);

                for(; p<tot; p+=step) {
                        if(get_effector_data(eff, &efd, point, 0)) {
                                efd.falloff= effector_falloff(eff, &efd, point, weights);
                                
                                if(efd.falloff > 0.0f)
                                        efd.falloff *= eff_calc_visibility(colliders, eff, &efd, point);

                                if(efd.falloff <= 0.0f)
                                        ;       /* don't do anything */
                                else if(eff->pd->forcefield == PFIELD_TEXTURE)
                                        do_texture_effector(eff, &efd, point, force);
                                else {
                                        float temp1[3]={0,0,0}, temp2[3];
                                        VECCOPY(temp1, force);

                                        do_physical_effector(eff, &efd, point, force);
                                        
                                        // for softbody backward compatibility
                                        if(point->flag & PE_WIND_AS_SPEED && impulse){
                                                VECSUB(temp2, force, temp1);
                                                VECSUB(impulse, impulse, temp2);
                                        }
                                }
                        }
                        else if(eff->flag & PE_VELOCITY_TO_IMPULSE && impulse) {
                                /* special case for harmonic effector */
                                VECADD(impulse, impulse, efd.vel);
                        }
                }
        }
}