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|
/* softbody.c
*
* $Id:
*
* ***** BEGIN GPL/BL DUAL 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. The Blender
* Foundation also sells licenses for use in proprietary software under
* the Blender License. See http://www.blender.org/BL/ for information
* about this.
*
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* The Original Code is Copyright (C) Blender Foundation
* All rights reserved.
*
* The Original Code is: all of this file.
*
* Contributor(s): none yet.
*
* ***** END GPL/BL DUAL LICENSE BLOCK *****
*/
/*
******
variables on the UI for now
typedef struct Object {
.....
float formfactor, softtime; softtime = #euler integrations steps per frame
.....
float sb_goalspring; softbody goal springs
float sb_goalfrict; softbody goal springs friction
float sb_inspring; softbody inner springs
float sb_infrict; softbody inner springs friction
float sb_nodemass; softbody mass of *vertex*
float sb_grav; softbody amount of gravitaion to apply
float sb_mingoal; quick limits for goal
float sb_maxgoal;
float sb_mediafrict; friction to env
float sb_pad1; free
*****
*/
#include <math.h>
#include <stdlib.h>
#include "MEM_guardedalloc.h"
/* types */
#include "DNA_ika_types.h"
#include "DNA_object_types.h"
#include "DNA_mesh_types.h"
#include "DNA_meshdata_types.h"
#include "DNA_scene_types.h"
#include "BLI_blenlib.h"
#include "BLI_arithb.h"
#include "BKE_global.h"
#include "BKE_utildefines.h"
#include "BKE_softbody.h"
#include "BKE_displist.h"
#include "BIF_editdeform.h"
/* ********** soft body engine ******* */
#define SOFTGOALSNAP 0.999f
// if bp-> goal is above make it a *forced follow original* and skip all ODE stuff for this bp
// removes *unnecessary* stiffnes from ODE system
#define HEUNWARNLIMIT 1 // 50 would be fine i think for detecting severe *stiff* stuff
float SoftHeunTol = 1.0f; // humm .. this should be calculated from sb parameters and sizes
float steptime = 1.0f/25.0f; // translate framerate to *real* time
float rescale_grav_to_framerate = 1.0f; // since unit of g is [m/sec^2] we need translation from frames to physics time
float rescale_friction_to_framerate = 1.0f; // since unit of drag is [kg/sec] we need translation from frames to physics time
short SB_ENABLE = 0; // quick hack to switch sb integration in 3d header
void softbody_scale_time(float steptime)
{
rescale_grav_to_framerate = steptime*steptime;
rescale_friction_to_framerate = steptime;
}
static int count_quads( Mesh *me)
{
int a,result = 0;
MFace *mface= me->mface;
if(mface ) {
for(a=me->totface; a>0; a--, mface++) {if(mface->v4) result++;}
}
return result;
}
static void add_quad_diag_springs(Object *ob)
{
Mesh *me= ob->data;
MFace *mface= me->mface;
BodyPoint *bp;
BodySpring *bs, *bs_new;
int a ;
if (ob->soft){
int nofquads;
nofquads = count_quads(me);
if (nofquads) {
/* resize spring-array to hold additional quad springs */
bs_new= MEM_callocN( (ob->soft->totspring + nofquads *2 )*sizeof(BodySpring), "bodyspring");
memcpy(bs_new,ob->soft->bspring,(ob->soft->totspring )*sizeof(BodySpring));
MEM_freeN(ob->soft->bspring); /* do this before reassigning the pointer or have a 1st class memory leak */
ob->soft->bspring = bs_new;
/* fill the tail */
a = 0;
bs = bs_new+ob->soft->totspring;
bp= ob->soft->bpoint;
if(mface ) {
for(a=me->totface; a>0; a--, mface++) {
if(mface->v4)
{
bs->v1= mface->v1;
bs->v2= mface->v3;
bs->strength= 1.0;
bs->len= VecLenf( (bp+bs->v1)->origS, (bp+bs->v2)->origS);
bs++;
bs->v1= mface->v2;
bs->v2= mface->v4;
bs->strength= 1.0;
bs->len= VecLenf( (bp+bs->v1)->origS, (bp+bs->v2)->origS);
bs++;
}
}
}
/* now we can announce new springs */
ob->soft->totspring += nofquads *2;
}
}
}
static void add_bp_springlist(BodyPoint *bp,int springID)
{
int *newlist;
if (bp->springs == NULL) {
bp->springs = MEM_callocN( sizeof(int), "bpsprings");
bp->springs[0] = springID;
bp->nofsprings = 1;
}
else {
bp->nofsprings++;
newlist = MEM_callocN(bp->nofsprings * sizeof(int), "bpsprings");
memcpy(newlist,bp->springs,(bp->nofsprings-1)* sizeof(int));
MEM_freeN(bp->springs);
bp->springs = newlist;
bp->springs[bp->nofsprings-1] = springID;
}
}
/* do this once when sb is build
it is O(N^2) so scanning for springs every iteration is too expensive
*/
static void build_bps_springlist(Object *ob)
{
SoftBody *sb= ob->soft; // is supposed to be there
BodyPoint *bp;
BodySpring *bs;
int a,b;
if (!sb) return; // paranoya check
for(a=sb->totpoint, bp= sb->bpoint; a>0; a--, bp++) {
/* scan for attached inner springs */
for(b=sb->totspring, bs= sb->bspring; b>0; b--, bs++) {
if (( (sb->totpoint-a) == bs->v1) ){
add_bp_springlist(bp,sb->totspring -b);
}
if (( (sb->totpoint-a) == bs->v2) ){
add_bp_springlist(bp,sb->totspring -b);
}
}//for springs
if (bp->nofsprings) printf(" node %d has %d spring links\n",a,bp->nofsprings);
}//for bp
}
static SoftBody *new_softbody(int totpoint, int totspring)
{
SoftBody *sb= NULL;
if(totpoint) {
sb= MEM_callocN(sizeof(SoftBody), "softbody");
sb->totpoint= totpoint;
sb->totspring= totspring;
sb->bpoint= MEM_mallocN( totpoint*sizeof(BodyPoint), "bodypoint");
if(totspring)
sb->bspring= MEM_mallocN( totspring*sizeof(BodySpring), "bodyspring");
}
return sb;
}
void free_softbody(SoftBody *sb)
{
if(sb) {
int a;
BodyPoint *bp;
if(sb->bpoint){
for(a=sb->totpoint, bp= sb->bpoint; a>0; a--, bp++) {
/* free spring list */
if (bp->springs != NULL) {
MEM_freeN(bp->springs);
}
}
MEM_freeN(sb->bpoint);
}
if(sb->bspring) MEM_freeN(sb->bspring);
MEM_freeN(sb);
}
}
/* ************ dynamics ********** */
/* aye this belongs to arith.c */
void Vec3PlusStVec(float *v, float s, float *v1)
{
v[0] += s*v1[0];
v[1] += s*v1[1];
v[2] += s*v1[2];
}
static void softbody_calc_forces(Object *ob, float dtime)
{
SoftBody *sb= ob->soft; // is supposed to be there
BodyPoint *bp;
float iks,ks,kd,gravity,actspringlen,forcefactor,sd[3];
int a,b;
BodyPoint *bproot;
BodySpring *bs;
/* clear forces */
for(a=sb->totpoint, bp= sb->bpoint; a>0; a--, bp++) {
bp->force[0]= bp->force[1]= bp->force[2]= 0.0;
}
gravity = ob->sb_nodemass * ob->sb_grav * rescale_grav_to_framerate;
iks = 1.0f/(1.0f-ob->sb_inspring)-1.0f ;/* inner spring constants function */
bproot= sb->bpoint; /* need this for proper spring addressing */
for(a=sb->totpoint, bp= sb->bpoint; a>0; a--, bp++) {
if(bp->goal < SOFTGOALSNAP){ // ommit this bp when i snaps
float auxvect[3]; // aux unit vector
float velgoal[3];
float absvel =0, projvel= 0;
/* do goal stuff */
/* true elastic goal */
VecSubf(auxvect,bp->origT,bp->pos);
ks = 1.0f/(1.0f- bp->goal*ob->sb_goalspring)-1.0f ;
bp->force[0]= ks*(auxvect[0]);
bp->force[1]= ks*(auxvect[1]);
bp->force[2]= ks*(auxvect[2]);
/* calulate damping forces generated by goals*/
VecSubf(velgoal,bp->origS, bp->origE);
kd = ob->sb_goalfrict * rescale_friction_to_framerate ;
if (dtime > 0.0 ) { // make sure friction does not become rocket motor on time reversal
bp->force[0]-= kd * (velgoal[0] + bp->vec[0]);
bp->force[1]-= kd * (velgoal[1] + bp->vec[1]);
bp->force[2]-= kd * (velgoal[2] + bp->vec[2]);
}
else {
bp->force[0]-= kd * (velgoal[0] - bp->vec[0]);
bp->force[1]-= kd * (velgoal[1] - bp->vec[1]);
bp->force[2]-= kd * (velgoal[2] - bp->vec[2]);
}
/* done goal stuff */
/* gravitation */
bp->force[2]-= gravity*ob->sb_nodemass; /* individual mass of node here */
/* friction in media */
kd= ob->sb_mediafrict* rescale_friction_to_framerate;
/* assume it to be proportional to actual velocity */
bp->force[0]-= bp->vec[0]*kd;
bp->force[1]-= bp->vec[1]*kd;
bp->force[2]-= bp->vec[2]*kd;
/* friction in media done */
/*other forces*/
/* this is the place where other forces can be added
yes, constraints and collision stuff should go here too (read baraff papers on that!)
*/
/*other forces done*/
/* nice things could be done with anisotropic friction
like wind/air resistance in normal direction
--> having a piece of cloth sailing down
but this needs to have a *valid* vertex normal
*valid* means to be calulated on time axis
hrms .. may be a rough one could be used as well .. let's see
*/
if (1){ /* big mesh optimization */
/* run over attached inner spring list */
if (sb->bspring){ // spring list exists at all ?
for(b=bp->nofsprings;b>0;b--){
bs = sb->bspring + bp->springs[b-1];
if (( (sb->totpoint-a) == bs->v1) ){
actspringlen= VecLenf( (bproot+bs->v2)->pos, bp->pos);
VecSubf(sd,(bproot+bs->v2)->pos, bp->pos);
Normalise(sd);
// friction stuff V1
VecSubf(velgoal,bp->vec,(bproot+bs->v2)->vec);
kd = ob->sb_infrict * rescale_friction_to_framerate ;
absvel = Normalise(velgoal);
projvel = ABS(Inpf(sd,velgoal));
kd *= absvel * projvel;
Vec3PlusStVec(bp->force,-kd,velgoal);
if(bs->len > 0.0) /* check for degenerated springs */
forcefactor = (bs->len - actspringlen)/bs->len * iks;
else
forcefactor = actspringlen * iks;
Vec3PlusStVec(bp->force,-forcefactor,sd);
}
if (( (sb->totpoint-a) == bs->v2) ){
actspringlen= VecLenf( (bproot+bs->v1)->pos, bp->pos);
VecSubf(sd,bp->pos,(bproot+bs->v1)->pos);
Normalise(sd);
// friction stuff V2
VecSubf(velgoal,bp->vec,(bproot+bs->v1)->vec);
kd = ob->sb_infrict * rescale_friction_to_framerate ;
absvel = Normalise(velgoal);
projvel = ABS(Inpf(sd,velgoal));
kd *= absvel * projvel;
Vec3PlusStVec(bp->force,-kd,velgoal);
if(bs->len > 0.0)
forcefactor = (bs->len - actspringlen)/bs->len * iks;
else
forcefactor = actspringlen * iks;
Vec3PlusStVec(bp->force,+forcefactor,sd);
}
}
} //if spring list exists at all ?
}
else{ // this branch is not completly uptaded for friction stuff
/* scan for attached inner springs makes it a O(N^2) thing = bad !*/
/* obsolete .. but if someone wants to try the effect :) */
for(b=sb->totspring, bs= sb->bspring; b>0; b--, bs++) {
if (( (sb->totpoint-a) == bs->v1) ){
actspringlen= VecLenf( (bproot+bs->v2)->pos, bp->pos);
VecSubf(sd,(bproot+bs->v2)->pos, bp->pos);
Normalise(sd);
if(bs->len > 0.0) /* check for degenerated springs */
forcefactor = (bs->len - actspringlen)/bs->len * iks;
else
forcefactor = actspringlen * iks;
Vec3PlusStVec(bp->force,-forcefactor,sd);
}
if (( (sb->totpoint-a) == bs->v2) ){
actspringlen= VecLenf( (bproot+bs->v1)->pos, bp->pos);
VecSubf(sd,bp->pos,(bproot+bs->v1)->pos);
Normalise(sd);
if(bs->len > 0.0)
forcefactor = (bs->len - actspringlen)/bs->len * iks;
else
forcefactor = actspringlen * iks;
Vec3PlusStVec(bp->force,+forcefactor,sd);
}
}// no snap
}//for
}
}
}
static void softbody_apply_forces(Object *ob, float dtime, int mode, float *err)
{
/* time evolution */
/* actually does an explicit euler step mode == 0 */
/* or heun ~ 2nd order runge-kutta steps, mode 1,2 */
SoftBody *sb= ob->soft; // is supposed to be there
BodyPoint *bp;
float dx[3],dv[3];
int a;
float timeovermass;
float maxerr = 0.0;
if (ob->sb_nodemass > 0.09999f) timeovermass = dtime/ob->sb_nodemass;
else timeovermass = dtime/0.09999f;
for(a=sb->totpoint, bp= sb->bpoint; a>0; a--, bp++) {
if(bp->goal < SOFTGOALSNAP){
/* so here is dv/dt = a = sum(F_springs)/m + gravitation + some friction forces */
/* the euler step for velocity then becomes */
/* v(t + dt) = v(t) + a(t) * dt */
bp->force[0]*= timeovermass; /* individual mass of node here */
bp->force[1]*= timeovermass;
bp->force[2]*= timeovermass;
/* some nasty if's to have heun in here too */
VECCOPY(dv,bp->force);
if (mode == 1){
VECCOPY(bp->prevvec,bp->vec);
VECCOPY(bp->prevdv ,dv);
}
if (mode ==2){
/* be optimistic and execute step */
bp->vec[0] = bp->prevvec[0] + 0.5f * (dv[0] + bp->prevdv[0]);
bp->vec[1] = bp->prevvec[1] + 0.5f * (dv[1] + bp->prevdv[1]);
bp->vec[2] = bp->prevvec[2] + 0.5f * (dv[2] + bp->prevdv[2]);
/* compare euler to heun to estimate error for step sizing */
maxerr = MAX2(maxerr,ABS(dv[0] - bp->prevdv[0]));
maxerr = MAX2(maxerr,ABS(dv[1] - bp->prevdv[1]));
maxerr = MAX2(maxerr,ABS(dv[2] - bp->prevdv[2]));
}
else {VECADD(bp->vec, bp->vec, bp->force);}
/* so here is dx/dt = v */
/* the euler step for location then becomes */
/* x(t + dt) = x(t) + v(t) * dt */
VECCOPY(dx,bp->vec);
dx[0]*=dtime ;
dx[1]*=dtime ;
dx[2]*=dtime ;
/* again some nasty if's to have heun in here too */
if (mode ==1){
VECCOPY(bp->prevpos,bp->pos);
VECCOPY(bp->prevdx ,dx);
}
if (mode ==2){
bp->pos[0] = bp->prevpos[0] + 0.5f * ( dx[0] + bp->prevdx[0]);
bp->pos[1] = bp->prevpos[1] + 0.5f * ( dx[1] + bp->prevdx[1]);
bp->pos[2] = bp->prevpos[2] + 0.5f* ( dx[2] + bp->prevdx[2]);
maxerr = MAX2(maxerr,ABS(dx[0] - bp->prevdx[0]));
maxerr = MAX2(maxerr,ABS(dx[1] - bp->prevdx[1]));
maxerr = MAX2(maxerr,ABS(dx[2] - bp->prevdx[2]));
}
else { VECADD(bp->pos, bp->pos, dx);}
}//snap
} //for
if (err){ /* so step size will be controlled by biggest difference in slope */
*err = maxerr;
}
}
/* used by heun when it overshoots */
static void softbody_restore_prev_step(Object *ob)
{
SoftBody *sb= ob->soft; // is supposed to be there
BodyPoint *bp;
int a;
for(a=sb->totpoint, bp= sb->bpoint; a>0; a--, bp++) {
VECCOPY(bp->vec,bp->prevvec);
VECCOPY(bp->pos,bp->prevpos);
}
}
/* unused */
static void softbody_apply_goal(Object *ob, float dtime)
{
SoftBody *sb= ob->soft; // is supposed to be there
BodyPoint *bp;
float vec[3], ks;
int a;
for(a=sb->totpoint, bp= sb->bpoint; a>0; a--, bp++) {
ks= bp->goal*dtime;
// this is hackish, screws up physics but stabilizes
vec[0]= ks*(bp->origT[0]-bp->pos[0]);
vec[1]= ks*(bp->origT[1]-bp->pos[1]);
vec[2]= ks*(bp->origT[2]-bp->pos[2]);
VECADD(bp->pos, bp->pos, vec);
ks= 1.0f-ks;
bp->vec[0]*= ks;
bp->vec[1]*= ks;
bp->vec[2]*= ks;
}
}
static void softbody_apply_goalsnap(Object *ob)
{
SoftBody *sb= ob->soft; // is supposed to be there
BodyPoint *bp;
int a;
for(a=sb->totpoint, bp= sb->bpoint; a>0; a--, bp++) {
if (bp->goal >= SOFTGOALSNAP){
VECCOPY(bp->prevpos,bp->pos);
VECCOPY(bp->pos,bp->origT);
}
}
}
static void softbody_force_goal(Object *ob)
{
SoftBody *sb= ob->soft; // is supposed to be there
BodyPoint *bp;
int a;
for(a=sb->totpoint, bp= sb->bpoint; a>0; a--, bp++) {
VECCOPY(bp->pos,bp->origT);
bp->vec[0] = bp->origE[0] - bp->origS[0];
bp->vec[1] = bp->origE[1] - bp->origS[1];
bp->vec[2] = bp->origE[2] - bp->origS[2];
}
}
static void interpolate_exciter(Object *ob, int timescale, int time)
{
Mesh *me= ob->data;
//MEdge *medge= me->medge;
int a;
BodyPoint *bp;
float f;
if(ob->soft) {
f = (float)time/(float)timescale;
bp= ob->soft->bpoint;
for(a=0; a<me->totvert; a++, bp++) {
bp->origT[0] = bp->origS[0] + f*(bp->origE[0] - bp->origS[0]);
bp->origT[1] = bp->origS[1] + f*(bp->origE[1] - bp->origS[1]);
bp->origT[2] = bp->origS[2] + f*(bp->origE[2] - bp->origS[2]);
if (bp->goal >= SOFTGOALSNAP){
bp->vec[0] = bp->origE[0] - bp->origS[0];
bp->vec[1] = bp->origE[1] - bp->origS[1];
bp->vec[2] = bp->origE[2] - bp->origS[2];
}
}
/* hrms .. do springs alter their lenght ?
if(medge) {
bs= ob->soft->bspring;
bp= ob->soft->bpoint;
for(a=0; (a<me->totedge && a < ob->soft->totspring ); a++, medge++, bs++) {
bs->len= VecLenf( (bp+bs->v1)->origT, (bp+bs->v2)->origT);
}
}
*/
}
}
/* ************ convertors ********** */
/* copy original (new) situation in softbody, as result of matrices or deform */
static void mesh_update_softbody(Object *ob)
{
Mesh *me= ob->data;
MVert *mvert= me->mvert;
MEdge *medge= me->medge;
BodyPoint *bp;
int a;
if(ob->soft) {
bp= ob->soft->bpoint;
for(a=0; a<me->totvert; a++, mvert++, bp++) {
VECCOPY(bp->origS, bp->origE);
VECCOPY(bp->origE, mvert->co);
Mat4MulVecfl(ob->obmat, bp->origE);
VECCOPY(bp->origT, bp->origE);
}
/* hrms .. do springs alter their lenght ?
if(medge) {
bs= ob->soft->bspring;
bp= ob->soft->bpoint;
for(a=0; (a<me->totedge && a < ob->soft->totspring ); a++, medge++, bs++) {
bs->len= VecLenf( (bp+bs->v1)->origE, (bp+bs->v2)->origE);
}
}
*/
}
}
int get_scalar_from_named_vertexgroup(Object *ob, char *name, int vertID, float *target)
/* result 0 on success, else indicates error number
-- kind of *inverse* result defintion,
-- but this way we can signal error condition to caller
-- and yes this function must not be here but in a *vertex group module*
*/
{
int i,groupindex;
bDeformGroup *locGroup = NULL;
MDeformVert *dv;
locGroup=get_named_vertexgroup (ob,name);
if(locGroup){
/* retrieve index for that group */
groupindex = get_defgroup_num (ob,locGroup);
/* spot the vert in deform vert list at mesh */
/* todo (coder paranoya) what if ob->data is not a mesh .. */
/* hrms.. would like to have the same for lattices anyhoo */
dv = ((Mesh*)ob->data)->dvert + vertID;
/* Lets see if this vert is in the weight group */
for (i=0; i<dv->totweight; i++){
if (dv->dw[i].def_nr == groupindex){
*target=dv->dw[i].weight; /* got it ! */
return 0;
}
}/*for*/
return 2;
}/*if(locGroup)*/
return 1;
}
/* makes totally fresh start situation */
static void mesh_to_softbody(Object *ob)
{
Mesh *me= ob->data;
MVert *mvert= me->mvert;
MEdge *medge= me->medge;
MFace *mface= me->mface;
BodyPoint *bp;
BodySpring *bs;
int a;
ob->soft= new_softbody(me->totvert, me->totedge);
if(ob->soft) {
bp= ob->soft->bpoint;
for(a=me->totvert; a>0; a--, mvert++, bp++) {
VECCOPY(bp->pos, mvert->co);
Mat4MulVecfl(ob->obmat, bp->pos); // yep, sofbody is global coords
VECCOPY(bp->origS, bp->pos);
VECCOPY(bp->origE, bp->pos);
VECCOPY(bp->origT, bp->pos);
bp->vec[0]= bp->vec[1]= bp->vec[2]= 0.0;
bp->weight= 1.0;
bp->goal= 0.5;
bp->nofsprings=0;
bp->springs=NULL;
if (1) { /* switch to vg scalars*/
/* get scalar values needed *per vertex* from vertex group functions,
so we can *paint* them nicly ..
they are normalized [0.0..1.0] so may be we need amplitude for scale
which can be done by caller
but still .. i'd like it to go this way
*/
int error;
char name[32] = "SOFTGOAL";
float temp;
error = get_scalar_from_named_vertexgroup(ob,name,me->totvert - a,&temp);
if (!error) bp->goal = temp;
if (bp->goal < ob->sb_mingoal) bp->goal = ob->sb_mingoal;
if (bp->goal > ob->sb_maxgoal) bp->goal = ob->sb_maxgoal;
/* a little ad hoc changing the goal control to be less *sharp* */
bp->goal = (float)pow(bp->goal,4.0f);
/* to proove the concept
this would enable per vertex *mass painting*
strcpy(name,"SOFTMASS");
error = get_scalar_from_named_vertexgroup(ob,name,me->totvert - a,&temp);
if (!error) bp->mass = temp * ob->rangeofmass;
*/
} /* switch to vg scalars */
}
if(medge) {
bs= ob->soft->bspring;
bp= ob->soft->bpoint;
for(a=me->totedge; a>0; a--, medge++, bs++) {
bs->v1= medge->v1;
bs->v2= medge->v2;
bs->strength= 1.0;
bs->len= VecLenf( (bp+bs->v1)->origS, (bp+bs->v2)->origS);
}
}
/* insert *diagonal* springs in quads if desired */
if (ob->softflag & 0x02) {
add_quad_diag_springs(ob);
}
build_bps_springlist(ob); /* big mesh optimization */
/* vertex colors are abused as weights here, however they're stored in faces... uhh */
/* naah .. we don't do it any more bjornmose :-)
if(mface && me->mcol) {
char *mcol= (char *)me->mcol;
for(a=me->totface; a>0; a--, mface++, mcol+=16) {
bp= ob->soft->bpoint+mface->v1;
if(bp->goal==0.5) {
bp->goal= ( (float)( (mcol + 0)[1] ) )/255.0;
}
bp= ob->soft->bpoint+mface->v2;
if(bp->goal==0.5) {
bp->goal= ( (float)( (mcol + 4)[1] ) )/255.0;
}
bp= ob->soft->bpoint+mface->v3;
if(bp->goal==0.5) {
bp->goal= ( (float)( (mcol + 8)[1]) )/255.0;
}
if(mface->v4) {
bp= ob->soft->bpoint+mface->v4;
if(bp->goal==0.5) {
bp->goal= ( (float)( (mcol + 12)[1]) )/255.0;
}
}
}
}
*/
bp= ob->soft->bpoint;
for(a=me->totvert; a>0; a--, bp++) {
//printf("a %d goal %f\n", a, bp->goal);
}
}
}
/* copies current sofbody position in mesh, so do this within modifier stacks! */
static void softbody_to_mesh(Object *ob)
{
Mesh *me= ob->data;
MVert *mvert;
BodyPoint *bp;
int a;
Mat4Invert(ob->imat, ob->obmat);
bp= ob->soft->bpoint;
mvert= me->mvert;
for(a=me->totvert; a>0; a--, mvert++, bp++) {
VECCOPY(mvert->co, bp->pos);
Mat4MulVecfl(ob->imat, mvert->co); // softbody is in global coords
}
}
/* makes totally fresh start situation */
static void lattice_to_softbody(Object *ob)
{
}
/* copies current sofbody position */
static void softbody_to_lattice(Object *ob)
{
}
/* ************ Object level, exported functions *************** */
/* copy original (new) situation in softbody, as result of matrices or deform */
void object_update_softbody(Object *ob)
{
switch(ob->type) {
case OB_MESH:
mesh_update_softbody(ob);
break;
case OB_LATTICE:
//lattice_update_softbody(ob);
break;
}
}
/* makes totally fresh start situation */
void object_to_softbody(Object *ob,float ctime)
{
if(ob->soft) free_softbody(ob->soft);
ob->soft= NULL;
switch(ob->type) {
case OB_MESH:
mesh_to_softbody(ob);
ob->soft->ctime = ctime;
break;
case OB_LATTICE:
lattice_to_softbody(ob);
break;
}
}
/* copies softbody result back in object */
void softbody_to_object(Object *ob)
{
if(ob->soft==NULL) return;
switch(ob->type) {
case OB_MESH:
softbody_to_mesh(ob);
break;
case OB_LATTICE:
softbody_to_lattice(ob);
break;
}
}
/* simulates one step. ctime is in frames not seconds */
void object_softbody_step(Object *ob, float ctime)
{
float dtime;
int timescale,t;
float forcetime;
float err;
/* this is a NO! NO!
==========================
if(ob->soft==NULL) {
object_to_softbody(ob);
if(ob->soft==NULL) return;
ob->soft->ctime= ctime;
}
// you can't create a soft object on the fly
// 1. inner spings need a *default* length for crinkles/wrinkles,
// surface area and volume preservation
// 2. initial conditions for velocities and positions need to be defined
// for a certain point of time .. say t0
// 3. and since we have friction and *outer* movement
// the history of the *outer* movements will affect where we end up
// sooo atm going to edit mode and back ( back calls object_to_softbody(ob,1.0f)
is the only way to create softbody data
*/
/* first attempt to set initial conditions for softbodies
rules
1. ODE solving is disabled / via button in 3dview header /otherways do regular softbody stuff
2. set SB positions to *goal*
3. set SB velocities to match *goal* movement
*/
if (SB_ENABLE == 0){
if(ob->soft==NULL) {
return; /* nothing to do */
}
object_update_softbody(ob);
ob->soft->ctime= ctime;
interpolate_exciter(ob,200,200);
softbody_force_goal(ob);
softbody_to_object(ob);
return; /* no dynamics wanted */
}
if(ob->soft==NULL) {
/* aye no soft object created bail out here */
printf("Softbody Zombie \n");
return;
}
softbody_scale_time(steptime); // translate frames/sec and lenghts unit to SI system
dtime= ctime - ob->soft->ctime;
// dtime= ABS(dtime); no no we want to go back in time with IPOs
timescale = (int)(ob->softtime * ABS(dtime));
if(ABS(dtime) > 0.0) {
object_update_softbody(ob);
if (ob->softflag & 0x04){
/* special case of 2nd order Runge-Kutta type AKA Heun */
float timedone =0.0;
/* counter for emergency brake
* we don't want to lock up the system if physics fail
*/
int loops =0 ;
SoftHeunTol = ob->softtime; // humm .. this should be calculated from sb parameters and sizes
forcetime = dtime; /* hope for integrating in one step */
while ( (ABS(timedone) < ABS(dtime)) && (loops < 2000) )
{
if (ABS(dtime) > 3.0 ){
printf("SB_STEPSIZE \n");
break; // sorry but i must assume goal movement can't be interpolated any more
}
//set goals in time
interpolate_exciter(ob,200,(int)(200.0*(timedone/dtime)));
// do predictive euler step
softbody_calc_forces(ob,forcetime);
softbody_apply_forces(ob,forcetime,1, NULL);
// crop new slope values to do averaged slope step
softbody_calc_forces(ob,forcetime);
softbody_apply_forces(ob,forcetime,2, &err);
softbody_apply_goalsnap(ob);
if (err > SoftHeunTol){ // error needs to be scaled to some quantity
softbody_restore_prev_step(ob);
forcetime /= 2.0;
}
else {
float newtime = forcetime * 1.1f; // hope for 1.1 times better conditions in next step
if (err > SoftHeunTol/2.0){ // stay with this stepsize unless err really small
newtime = forcetime;
}
timedone += forcetime;
if (forcetime > 0.0)
forcetime = MIN2(dtime - timedone,newtime);
else
forcetime = MAX2(dtime - timedone,newtime);
}
loops++;
}
// move snapped to final position
interpolate_exciter(ob,2,2);
softbody_apply_goalsnap(ob);
if (loops > HEUNWARNLIMIT) /* monitor high loop counts say 1000 after testing */
printf("%d heun integration loops/frame \n",loops);
}
else
/* do brute force explicit euler */
/* inner intagration loop */
/* */
// loop n times so that n*h = duration of one frame := 1
// x(t+h) = x(t) + h*v(t);
// v(t+h) = v(t) + h*f(x(t),t);
for(t=1 ; t <= timescale; t++) {
if (ABS(dtime) > 15 ) break;
/* the *goal* mesh must use the n*h timing too !
use *cheap* linear intepolation for that */
interpolate_exciter(ob,timescale,t);
if (timescale > 0 )
{
forcetime = dtime/timescale;
/* does not fit the concept sloving ODEs :) */
/* softbody_apply_goal(ob,forcetime ); */
/* explicit Euler integration */
/* we are not controling a nuclear power plant!
so rought *almost* physical behaviour is acceptable.
in cases of *mild* stiffnes cranking up timscale -> decreasing stepsize *h*
avoids instability */
softbody_calc_forces(ob,forcetime);
softbody_apply_forces(ob,forcetime,0, NULL);
softbody_apply_goalsnap(ob);
// if (0){
/* ok here comes the überhammer
use a semi implicit euler integration to tackle *all* stiff conditions
but i doubt the cost/benifit holds for most of the cases
-- to be coded*/
// }
}
}
/* and apply to vertices */
softbody_to_object(ob);
ob->soft->ctime= ctime;
} // if(ABS(dtime) > 0.0)
else {
// rule : you have asked for the current state of the softobject
// since dtime= ctime - ob->soft->ctime;
// and we were not notifified about any other time changes
// so here it is !
softbody_to_object(ob);
}
}
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