It works, png is output. The only problem is that some triangles are missing

Samo Penic

2014-06-13 a61c001cd35ff70a314ef417c4beda9c7e68d3ad

 src/cross-section.c

@@ -1,7 +1,7 @@
#include<general.h>
#include<cross-section.h>
#include<coord.h>

#include<cairo/cairo.h>
/** @brief Calculates cross-section of vesicle with plane.
 *
 * Function returns points of cross-section of vesicle with plane. Plane is described with equation $ax+by+cz+d=0$. Algorithm extracts coordinates of each vertex of a vesicle and then:
@@ -12,12 +12,14 @@
ts_coord_list *get_crossection_with_plane(ts_vesicle *vesicle,ts_double a,ts_double b,ts_double c, ts_double d){


   ts_uint i, j;
   ts_uint i, j,k;
   ts_double pp,Dsq; // distance from the plane squared
   ts_double ppn; // distance from the plane squared of a neighbor
   ts_double ppn1,ppn2; // distance from the plane squared of a neighbor
   ts_double u; //factor to scale vector from first vector to the second to get intersection
   ts_vertex *vtx;

   ts_uint ntria=0; // number triangles
   ts_uint cnt=0;
   ts_triangle *tria[2]; // list of triangles
   ts_coord_list *pts=init_coord_list();
   for(i=0;i<vesicle->vlist->n;i++){
      vtx=vesicle->vlist->vtx[i];
@@ -26,13 +28,67 @@
      Dsq=pp*pp/(a*a+b*b+c*c);
      if(Dsq<vesicle->dmax){
         for(j=0;j<vtx->neigh_no;j++){
            ppn=vtx->neigh[j]->x*a+vtx->neigh[j]->y*b+vtx->neigh[j]->z*c+d;
            if(pp*ppn<0){ //the combination of vertices are good candidates for a crossection
            ppn1=vtx->neigh[j]->x*a+vtx->neigh[j]->y*b+vtx->neigh[j]->z*c+d;
            if(pp*ppn1<=0){ //the combination of vertices are good candidates for a crossection
/*               u=pp/(a*(vtx->x-vtx->neigh[j]->x)+b*(vtx->y-vtx->neigh[j]->y)+c*(vtx->z-vtx->neigh[j]->z));
               add_coord(pts, vtx->x+u*(vtx->neigh[j]->x - vtx->x),
                     vtx->y+u*(vtx->neigh[j]->y - vtx->y),		
                     vtx->z+u*(vtx->neigh[j]->z - vtx->z),
                     TS_COORD_CARTESIAN);		

*/
               //find triangle that belongs to the two vertices
               cnt=0;
               ntria=0;
               for(k=0;k<vtx->tristar_no;k++){
                  if(vtx->tristar[k]->vertex[1]==vtx->neigh[j] && vtx->tristar[k]->vertex[0]==vtx){ 
                     //triangle found.
                     tria[ntria]=vtx->tristar[k];
                     ntria++;
                  }
               }
               // if ntria !=1 there is probably something wrong I would say...
               if(ntria==0) continue;
               if(ntria!=1) {
                  fprintf(stderr,"ntria=%u\n",ntria);
                  fatal ("Error in mesh. 1 triangle not found",123123);
               }
               //find the two intersections (in general) to form a intersection line
               /* we dont know which vertex is which, so we need to recalculate all previously calculated values*/
               pp=vtx->x*a+vtx->y*b+vtx->z*c+d;
               ppn1=vtx->neigh[j]->x*a+vtx->neigh[j]->y*b+vtx->neigh[j]->z*c+d;

               u=pp/(a*(vtx->x-vtx->neigh[j]->x)+b*(vtx->y-vtx->neigh[j]->y)+c*(vtx->z-vtx->neigh[j]->z));
               add_coord(pts, vtx->x+u*(vtx->neigh[j]->x - vtx->x),
                     vtx->y+u*(vtx->neigh[j]->y - vtx->y),      
                     vtx->z+u*(vtx->neigh[j]->z - vtx->z),
                     TS_COORD_CARTESIAN);      
               ppn2=tria[0]->vertex[2]->x*a+tria[0]->vertex[2]->y*b+tria[0]->vertex[2]->z*c+d;	
               cnt++;
               //two more tries to find anothen pair of vertices, one above and one below the intersection plane */	
               if(pp*ppn2<=0) {
                  u=pp/(a*(vtx->x-tria[0]->vertex[2]->x)+b*(vtx->y-tria[0]->vertex[2]->y)+c*(vtx->z-tria[0]->vertex[2]->z));
                  add_coord(pts, vtx->x+u*(tria[0]->vertex[2]->x - vtx->x),
                     vtx->y+u*(tria[0]->vertex[2]->y - vtx->y),		
                     vtx->z+u*(tria[0]->vertex[2]->z - vtx->z),
                     TS_COORD_CARTESIAN);	
                  cnt++;
               }

               if(ppn2*ppn1<=0) {
                  u=ppn1/(a*(vtx->neigh[j]->x-tria[0]->vertex[2]->x)+b*(vtx->neigh[j]->y-tria[0]->vertex[2]->y)+c*(vtx->neigh[j]->z-tria[0]->vertex[2]->z));
                  add_coord(pts, vtx->neigh[j]->x+u*(tria[0]->vertex[2]->x - vtx->neigh[j]->x),
                     vtx->neigh[j]->y+u*(tria[0]->vertex[2]->y - vtx->neigh[j]->y),		
                     vtx->neigh[j]->z+u*(tria[0]->vertex[2]->z - vtx->neigh[j]->z),
                     TS_COORD_CARTESIAN);	
                  cnt++;

               }


               if(cnt!=2){
                  fprintf(stderr,"Hey, cnt=%u",cnt);
               }
            }
         }
      }
@@ -41,3 +97,28 @@
}


/** Saves calculated crossection as a png image */
ts_bool crossection_to_png(ts_coord_list *pts, char *filename){

   cairo_surface_t *surface;
   cairo_t *cr;
   ts_uint i;
   surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 1800, 1800);
   cr = cairo_create (surface);
   cairo_rectangle(cr, 0.0, 0.0, 1800,1800);
   cairo_set_source_rgb(cr, 0.3, 0.3, 0.3);
   cairo_fill(cr);
   cairo_set_line_width (cr, 5.0/30.0);
   cairo_translate(cr, 900,900);
   cairo_scale (cr, 30, 30);
   cairo_set_source_rgb (cr, 1.0, 1.0, 1.0);

   for(i=0;i<pts->n;i+=2){
      cairo_move_to(cr, pts->coord[i]->e1, pts->coord[i]->e2);
      cairo_line_to(cr, pts->coord[i+1]->e1, pts->coord[i+1]->e2);
   }
   cairo_stroke(cr);
   cairo_surface_write_to_png (surface,filename);
   cairo_surface_finish (surface);	
   return TS_SUCCESS;
}