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new softbody feature:

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simple (naive) self collision
estimates a collision ball
using the spring lenght to attached neighbours
(idea stolen from old cloth modifier files, but i'm sure ZAZ and genscher won't mind)
-- usefull for untangeling static cloth like objects
-- may be used for cloth simulation with known limitations
like 'tunnel effect' if objects are moving too fast ...

demo -- volatile files
http://www.wund.homepage.t-online.de/hidden/sb_without_selfcol.avi
http://www.wund.homepage.t-online.de/hidden/sb_with_selfcoll.avi

have fun
BM
This commit is contained in:
Jens Ole Wund 2006-09-28 20:27:46 +00:00
parent 22ce0faffe
commit 8e7b403924
3 changed files with 79 additions and 6 deletions
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79
source/blender/blenkernel/intern/softbody.c
View File

@ -92,6 +92,7 @@ typedef struct BodyPoint {
float prevpos[3], prevvec[3], prevdx[3], prevdv[3]; /* used for Heun integration */
int nofsprings; int *springs;
float contactfrict;
float colball;
} BodyPoint;
typedef struct BodySpring {
@ -673,6 +674,27 @@ static void build_bps_springlist(Object *ob)
}/*for bp*/
}
static void calculate_collision_balls(Object *ob)
{
SoftBody *sb= ob->soft; /* is supposed to be there */
BodyPoint *bp;
BodySpring *bs;
int a,b;
if (sb==NULL) return; /* paranoya check */
for(a=sb->totpoint, bp= sb->bpoint; a>0; a--, bp++) {
bp->colball=0;
for(b=bp->nofsprings;b>0;b--){
bs = sb->bspring + bp->springs[b-1];
bp->colball += bs->len;
}
if (bp->nofsprings != 0) bp->colball /= bp->nofsprings;
else bp->colball=0;
/* printf("collision ballsize %f \n",bp->colball); */
}/*for bp*/
}
/* creates new softbody if didn't exist yet, makes new points and springs arrays */
static void renew_softbody(Object *ob, int totpoint, int totspring)
@ -984,7 +1006,7 @@ static void softbody_calc_forces(Object *ob, float forcetime)
ListBase *do_effector;
float iks, ks, kd, gravity, actspringlen, forcefactor, sd[3];
float fieldfactor = 1000.0f, windfactor = 250.0f;
int a, b, do_deflector;
int a, b, do_deflector;
/* clear forces */
for(a=sb->totpoint, bp= sb->bpoint; a>0; a--, bp++) {
@ -1001,7 +1023,7 @@ static void softbody_calc_forces(Object *ob, float forcetime)
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 */
if(bp->goal < SOFTGOALSNAP){ /* ommit this bp when it snaps */
float auxvect[3];
float velgoal[3];
float absvel =0, projvel= 0;
@ -1084,7 +1106,57 @@ static void softbody_calc_forces(Object *ob, float forcetime)
bp->contactfrict = 0.0f;
}
}
else
{
bp->contactfrict = 0.0f;
}
/* naive ball self collision */
if((ob->softflag & OB_SB_EDGES) && (sb->bspring)
&& (ob->softflag & OB_SB_SELF)){
int attached;
BodyPoint *obp;
int c,b;
float def[3];
float tune2 = 0.5f;
float tune = 1.0f;
float distance;
float compare;
for(c=sb->totpoint, obp= sb->bpoint; c>0; c--, obp++) {
if (c < a ) continue; /* exploit force(a,b) == force(b,a) part1/2 */
compare = (obp->colball + bp->colball) * tune2;
VecSubf(def, bp->pos, obp->pos);
distance = Normalise(def);
if (distance < compare ){
/* exclude body points attached with a spring */
attached = 0;
for(b=obp->nofsprings;b>0;b--){
bs = sb->bspring + obp->springs[b-1];
if (( sb->totpoint-a == bs->v2) || ( sb->totpoint-a == bs->v1)){
attached=1;
continue;}
}
if (!attached){
/* would need another UI parameter defining fricton on self contact */
float ccfriction = 0.05;
float f = tune/(distance) + tune/(compare*compare)*distance - 2.0f*tune/compare ;
Vec3PlusStVec(bp->force,f,def);
if (bp->contactfrict == 0.0f) bp->contactfrict = ccfriction*compare/distance;
/* exploit force(a,b) == force(b,a) part2/2 */
Vec3PlusStVec(obp->force,-f,def);
if (obp->contactfrict == 0.0f) obp->contactfrict = ccfriction*compare/distance;
}
}
}
}
/* naive ball self collision done */
/*other forces done*/
/* nice things could be done with anisotropic friction
@ -1147,7 +1219,6 @@ static void softbody_calc_forces(Object *ob, float forcetime)
}/*any edges*/
}/*omit on snap */
}/*loop all bp's*/
/* cleanup */
if(do_effector)
pdEndEffectors(do_effector);
@ -1429,13 +1500,13 @@ static void mesh_to_softbody(Object *ob)
}
build_bps_springlist(ob); /* scan for springs attached to bodypoints ONCE */
/* insert *other second order* springs if desired */
if (sb->secondspring > 0.0000001f) {
add_2nd_order_springs(ob,sb->secondspring); /* exploits the the first run of build_bps_springlist(ob);*/
build_bps_springlist(ob); /* yes we need to do it again*/
}
springs_from_mesh(ob); /* write the 'rest'-lenght of the springs */
calculate_collision_balls(ob);
}
}

1
source/blender/makesdna/DNA_object_force.h
View File

@ -123,6 +123,7 @@ typedef struct SoftBody {
#define OB_SB_BAKESET 64
#define OB_SB_BAKEDO 128
#define OB_SB_RESET 256
#define OB_SB_SELF 512
#ifdef __cplusplus
}

5
source/blender/src/buttons_object.c
View File

@ -2355,8 +2355,9 @@ static void object_softbodies(Object *ob)
/* EDGE SPRING STUFF */
if(ob->type!=OB_SURF) {
uiBlockBeginAlign(block);
uiDefButBitS(block, TOG, OB_SB_EDGES, B_SOFTBODY_CHANGE, "Use Edges", 10,30,150,20, &ob->softflag, 0, 0, 0, 0, "Use Edges as springs");
uiDefButBitS(block, TOG, OB_SB_QUADS, B_SOFTBODY_CHANGE, "Stiff Quads", 160,30,150,20, &ob->softflag, 0, 0, 0, 0, "Adds diagonal springs on 4-gons");
uiDefButBitS(block, TOG, OB_SB_EDGES, B_SOFTBODY_CHANGE, "Use Edges", 10,30,90,20, &ob->softflag, 0, 0, 0, 0, "Use Edges as springs");
uiDefButBitS(block, TOG, OB_SB_QUADS, B_SOFTBODY_CHANGE, "Stiff Quads", 110,30,90,20, &ob->softflag, 0, 0, 0, 0, "Adds diagonal springs on 4-gons");
uiDefButBitS(block, TOG, OB_SB_SELF, B_DIFF, "Self Collision", 220,30,90,20, &ob->softflag, 0, 0, 0, 0, "Use Edges as springs");
uiDefButF(block, NUM, B_DIFF, "E Stiff:", 10,10,150,20, &sb->inspring, 0.0, 0.999, 10, 0, "Edge spring stiffness");
uiDefButF(block, NUM, B_DIFF, "E Damp:", 160,10,150,20, &sb->infrict, 0.0, 50.0, 10, 0, "Edge spring friction");
uiBlockEndAlign(block);