| 984 |
|
|
| 985 |
|
|
| 986 |
|
|
| 987 |
+ |
/* |
| 988 |
+ |
* int |
| 989 |
+ |
* smRay(FVECT orig, FVECT dir,FVECT v0,FVECT v1,FVECT v2,FVECT r) |
| 990 |
+ |
* |
| 991 |
+ |
* Intersect the ray with triangle v0v1v2, return intersection point in r |
| 992 |
+ |
* |
| 993 |
+ |
* Assumes orig,v0,v1,v2 are in spherical coordinates, and orig is |
| 994 |
+ |
* unit |
| 995 |
+ |
*/ |
| 996 |
+ |
int |
| 997 |
+ |
traceRay(orig,dir,v0,v1,v2,r) |
| 998 |
+ |
FVECT orig,dir; |
| 999 |
+ |
FVECT v0,v1,v2; |
| 1000 |
+ |
FVECT r; |
| 1001 |
+ |
{ |
| 1002 |
+ |
FVECT n,p[3],d; |
| 1003 |
+ |
double pt[3],r_eps; |
| 1004 |
+ |
char i; |
| 1005 |
+ |
int which; |
| 1006 |
+ |
|
| 1007 |
+ |
/* Find the plane equation for the triangle defined by the edge v0v1 and |
| 1008 |
+ |
the view center*/ |
| 1009 |
+ |
VCROSS(n,v0,v1); |
| 1010 |
+ |
/* Intersect the ray with this plane */ |
| 1011 |
+ |
i = intersect_ray_plane(orig,dir,n,0.0,&(pt[0]),p[0]); |
| 1012 |
+ |
if(i) |
| 1013 |
+ |
which = 0; |
| 1014 |
+ |
else |
| 1015 |
+ |
which = -1; |
| 1016 |
+ |
|
| 1017 |
+ |
VCROSS(n,v1,v2); |
| 1018 |
+ |
i = intersect_ray_plane(orig,dir,n,0.0,&(pt[1]),p[1]); |
| 1019 |
+ |
if(i) |
| 1020 |
+ |
if((which==-1) || pt[1] < pt[0]) |
| 1021 |
+ |
which = 1; |
| 1022 |
+ |
|
| 1023 |
+ |
VCROSS(n,v2,v0); |
| 1024 |
+ |
i = intersect_ray_plane(orig,dir,n,0.0,&(pt[2]),p[2]); |
| 1025 |
+ |
if(i) |
| 1026 |
+ |
if((which==-1) || pt[2] < pt[which]) |
| 1027 |
+ |
which = 2; |
| 1028 |
+ |
|
| 1029 |
+ |
if(which != -1) |
| 1030 |
+ |
{ |
| 1031 |
+ |
/* Return point that is K*eps along projection of the ray on |
| 1032 |
+ |
the sphere to push intersection point p[which] into next cell |
| 1033 |
+ |
*/ |
| 1034 |
+ |
normalize(p[which]); |
| 1035 |
+ |
/* Calculate the ray perpendicular to the intersection point: approx |
| 1036 |
+ |
the direction moved along the sphere a distance of K*epsilon*/ |
| 1037 |
+ |
r_eps = -DOT(p[which],dir); |
| 1038 |
+ |
VSUM(n,dir,p[which],r_eps); |
| 1039 |
+ |
/* Calculate the length along ray p[which]-dir needed to move to |
| 1040 |
+ |
cause a move along the sphere of k*epsilon |
| 1041 |
+ |
*/ |
| 1042 |
+ |
r_eps = DOT(n,dir); |
| 1043 |
+ |
VSUM(r,p[which],dir,(20*FTINY)/r_eps); |
| 1044 |
+ |
normalize(r); |
| 1045 |
+ |
return(TRUE); |
| 1046 |
+ |
} |
| 1047 |
+ |
else |
| 1048 |
+ |
{ |
| 1049 |
+ |
/* Unable to find intersection: move along ray and try again */ |
| 1050 |
+ |
r_eps = -DOT(orig,dir); |
| 1051 |
+ |
VSUM(n,dir,orig,r_eps); |
| 1052 |
+ |
r_eps = DOT(n,dir); |
| 1053 |
+ |
VSUM(r,orig,dir,(20*FTINY)/r_eps); |
| 1054 |
+ |
normalize(r); |
| 1055 |
+ |
#ifdef DEBUG |
| 1056 |
+ |
eputs("traceRay:Ray does not intersect triangle"); |
| 1057 |
+ |
#endif |
| 1058 |
+ |
return(FALSE); |
| 1059 |
+ |
} |
| 1060 |
+ |
} |
| 1061 |
+ |
|
| 1062 |
|
|
| 1063 |
|
|
| 1064 |
|
|
