Torque3D-clone/Engine/lib/bullet/examples/Experiments/ImplicitCloth/stan/vec3n.cpp

//
// Big Vector and Sparse Matrix Classes
// 

#include <float.h>

#include "vec3n.h"


float conjgrad_lasterror;
float conjgrad_epsilon = 0.1f;
int   conjgrad_loopcount;
int   conjgrad_looplimit = 100;

/*EXPORTVAR(conjgrad_lasterror);
EXPORTVAR(conjgrad_epsilon  );
EXPORTVAR(conjgrad_loopcount);
EXPORTVAR(conjgrad_looplimit);
*/

int  ConjGradient(float3N &X, float3Nx3N &A, float3N &B)
{
       // Solves for unknown X in equation AX=B
       conjgrad_loopcount=0;
       int n=B.count;
       float3N q(n),d(n),tmp(n),r(n);
       r = B - Mul(tmp,A,X);    // just use B if X known to be zero
       d = r;
       float s = dot(r,r);
       float starget = s * squared(conjgrad_epsilon);
       while( s>starget && conjgrad_loopcount++ < conjgrad_looplimit)
       {
               Mul(q,A,d); // q = A*d;
               float a = s/dot(d,q);
               X = X + d*a;
               if(conjgrad_loopcount%50==0)
               {
                       r = B - Mul(tmp,A,X);
               }
               else
               {
                       r = r - q*a;
               }
               float s_prev = s;
               s = dot(r,r);
               d = r+d*(s/s_prev);
       }
       conjgrad_lasterror = s;
       return conjgrad_loopcount<conjgrad_looplimit;  // true means we reached desired accuracy in given time - ie stable
}


int  ConjGradientMod(float3N &X, float3Nx3N &A, float3N &B,int3 hack)
{
// obsolete!!!
       // Solves for unknown X in equation AX=B
       conjgrad_loopcount=0;
       int n=B.count;
       float3N q(n),d(n),tmp(n),r(n);
       r = B - Mul(tmp,A,X);    // just use B if X known to be zero
       r[hack[0]] = r[hack[1]] = r[hack[2]] = float3(0,0,0);
       d = r;
       float s = dot(r,r);
       float starget = s * squared(conjgrad_epsilon);
       while( s>starget && conjgrad_loopcount++ < conjgrad_looplimit)
       {
               Mul(q,A,d); // q = A*d;
               q[hack[0]] = q[hack[1]] = q[hack[2]] = float3(0,0,0);
               float a = s/dot(d,q);
               X = X + d*a;
               if(conjgrad_loopcount%50==0)
               {
                       r = B - Mul(tmp,A,X);
                       r[hack[0]] = r[hack[1]] = r[hack[2]] = float3(0,0,0);
               }
               else
               {
                       r = r - q*a;
               }
               float s_prev = s;
               s = dot(r,r);
               d = r+d*(s/s_prev);
               d[hack[0]] = d[hack[1]] = d[hack[2]] = float3(0,0,0);
       }
       conjgrad_lasterror = s;
       return conjgrad_loopcount<conjgrad_looplimit;  // true means we reached desired accuracy in given time - ie stable
}



static inline void filter(float3N &V,const float3Nx3N &S)
{
       for(int i=0;i<S.blocks.count;i++)
       {
               V[S.blocks[i].r] = V[S.blocks[i].r]*S.blocks[i].m;
       }
}

int  ConjGradientFiltered(float3N &X, const float3Nx3N &A, const float3N &B,const float3Nx3N &S)
{
       // Solves for unknown X in equation AX=B
       conjgrad_loopcount=0;
       int n=B.count;
       float3N q(n),d(n),tmp(n),r(n);
       r = B - Mul(tmp,A,X);    // just use B if X known to be zero
       filter(r,S);
       d = r;
       float s = dot(r,r);
       float starget = s * squared(conjgrad_epsilon);
       while( s>starget && conjgrad_loopcount++ < conjgrad_looplimit)
       {
               Mul(q,A,d); // q = A*d;
               filter(q,S);
               float a = s/dot(d,q);
               X = X + d*a;
               if(conjgrad_loopcount%50==0)
               {
                       r = B - Mul(tmp,A,X);
                       filter(r,S);
               }
               else
               {
                       r = r - q*a;
               }
               float s_prev = s;
               s = dot(r,r);
               d = r+d*(s/s_prev);
               filter(d,S);
       }
       conjgrad_lasterror = s;
       return conjgrad_loopcount<conjgrad_looplimit;  // true means we reached desired accuracy in given time - ie stable
}




// test big vector math library:
static void testfloat3N()
{
       float3N a(2),b(2),c(2);
       a[0] = float3(1,2,3);
       a[1] = float3(4,5,6);
       b[0] = float3(10,20,30);
       b[1] = float3(40,50,60);
//      c =  a+b+b * 10.0f;
//      float d = dot(a+b,-b);
       int k;
       k=0;
}
class dotest{public:dotest(){testfloat3N();}}do_test_at_program_startup;