-> Path Select Tool

Added a new tool to the 'W-Key' popup menu in mesh editmode, 'Path Select'.
When exactly two vertices are selected, 'Path Select' will find the shortest
path of vertices between them. There are two methods for determining
the shortest path, one that finds the path with shortest physical
distance, and one that finds the path with shortest topological distance.

Examples:

Original Selection
http://www.umsl.edu/~gcbq44/pathselect.jpg

Path Select - Edge Length
http://www.umsl.edu/~gcbq44/pathselect-shortestphysical.jpg

Path Select - Topological
http://www.umsl.edu/~gcbq44/pathselect-topological.jpg

The tool uses a straightforward implementation of Dijsktra's algorithm
and may be a bit slow on extremely large meshes. As a speedup you can
hide the parts of the mesh that you are not working on and they will
not be searched.

source/blender/include/BIF_editmesh.h

@@ -208,5 +208,7 @@ int collapseFaces(int uvmerge);
 int merge_firstlast(int first, int uvmerge);
 int merge_target( int target, int uvmerge);
 
+void pathselect(void);
+
 #endif
 

source/blender/src/editmesh_tools.c

@@ -40,6 +40,7 @@ editmesh_tool.c: UI called tools for editmesh, geometry changes here, otherwise
 #include <string.h>
 #include <math.h>
 
+
 #ifdef HAVE_CONFIG_H
 #include <config.h>
 #endif
@@ -6077,5 +6078,175 @@ int merge_target(int target, int uvmerge)
 }
 #undef MERGELIMIT
 
+typedef struct PathNode{
+	struct PathNode *next, *prev;
+	int u;
+	ListBase edges;
+} PathNode;
+
+typedef struct PathEdge{
+	struct PathEdge *next, *prev;
+	int v;
+	float w;
+} PathEdge;
+
+static PathNode *Extract_Min(ListBase *Q, float *d)
+{
+	PathNode *currpn, *minpn;
+	int min;
+	
+	min=((PathNode*)Q->last)->u;
+	
+	for(currpn=(PathNode*)Q->first; currpn; currpn=currpn->next){
+		if(d[currpn->u] <= d[min]){ 
+			min = currpn->u;
+			minpn = currpn;
+		}
+	}
+	return(minpn);
+}
+
+void pathselect(void)
+{
+	EditVert *eve, *s, *t;
+	EditEdge *eed;
+	PathEdge *newpe, *currpe;
+	PathNode *newpn, *currpn;
+	ListBase Q,S;
+	int v, *previous, pathvert;
+	int unbalanced, totnodes;
+	short physical;
+	float *d;
+	
+	Q.first = Q.last = 0;
+	S.first = S.last = 0;
+	s = t = NULL;
+	
+	countall(); /*paranoid?*/
+	if(G.totvertsel == 2){
+		physical= pupmenu("Distance Method? %t|Edge Length%x1|Topological%x0");
+		for(eve=G.editMesh->verts.first; eve; eve=eve->next){
+			if(t) break;
+			else{
+				if(eve->f&SELECT){
+					if(s) t = eve;
+					else s = eve;
+				}
+			}
+		}
+		/*need to find out if t is actually reachable by s....*/
+		for(eve=G.editMesh->verts.first; eve; eve=eve->next){ 
+			eve->f1 = 0;
+		}
+		
+		s->f1 = 1;
+		
+		unbalanced = 1;
+		
+		while(unbalanced){
+			unbalanced = 0;
+			for(eed=G.editMesh->edges.first; eed; eed=eed->next){
+				if(eed->h == 0){
+					if(eed->v1->f1 && !eed->v2->f1){ 
+						eed->v2->f1 = 1;
+						unbalanced = 1;
+					}
+					else if(eed->v2->f1 && !eed->v1->f1){
+						eed->v1->f1 = 1;
+						unbalanced = 1;
+					}
+				}
+			}
+			
+			/*if(s->f1 == t->f1) break; */
+			
+		}
+		
+		if(s->f1 && t->f1){ /*t can be reached by s*/
+			totnodes = 0;
+			for(eve=G.editMesh->verts.first; eve; eve=eve->next){
+				if(eve->f1){
+					eve->tmp.l = totnodes; /*store index*/
+					newpn = MEM_mallocN(sizeof(PathNode), "Path Node");
+					newpn->u = eve->tmp.l;
+					newpn->next = 0;
+					newpn->prev = 0;
+					newpn->edges.first = 0;
+					newpn->edges.last = 0;
+					BLI_addtail(&Q, newpn);
+					totnodes++;
+				}
+				else eve->tmp.l = -1; /*paranoia*/
+			}
+			
+			for(eed=G.editMesh->edges.first; eed; eed=eed->next){
+				for(currpn = Q.first; currpn; currpn=currpn->next){
+					if(eed->v1->f1 && eed->v1->tmp.l == currpn->u){
+						newpe = MEM_mallocN(sizeof(PathEdge), "Path Edge");
+						newpe->v = eed->v2->tmp.l;
+						if(physical){
+							newpe->w = VecLenf(eed->v1->co, eed->v2->co);
+						}
+						else newpe->w = 1;
+						newpe->next = 0;
+						newpe->prev = 0;
+						BLI_addtail(&(currpn->edges), newpe);
+					} else 
+					if(eed->v2->f1 && eed->v2->tmp.l == currpn->u){
+						newpe = MEM_mallocN(sizeof(PathEdge), "Path Edge");
+						newpe->v = eed->v1->tmp.l;
+						if(physical){
+							newpe->w = VecLenf(eed->v1->co, eed->v2->co);
+						}
+						else newpe->w = 1;
+						newpe->next = 0;
+						newpe->prev = 0;
+						BLI_addtail(&(currpn->edges), newpe);
+					}
+				}
+			}
+			
+			d = MEM_callocN(sizeof(float)*totnodes, "path select distances");
+			previous = MEM_callocN(sizeof(int)*totnodes, "indices");
+			
+			for(v=0; v < totnodes; v++){
+				d[v] = 100000;	/*some impossibly large number.... redefine this better*/
+				previous[v] = -1; /*array of indices*/
+			}
+			
+			d[s->tmp.l] = 0;
+			
+			while(Q.first){
+				currpn = Extract_Min(&Q,d);
+				BLI_remlink(&Q, currpn);
+				BLI_addtail(&S, currpn);
+				
+				for(currpe=currpn->edges.first; currpe; currpe=currpe->next){
+					if(d[currpe->v] > (d[currpn->u] + currpe->w)){
+						d[currpe->v] = d[currpn->u] + currpe->w;
+						previous[currpe->v] = currpn->u;
+					}
+				}
+			}
+			
+			pathvert = t->tmp.l;
+			while(pathvert != -1){
+				for(eve=G.editMesh->verts.first; eve; eve=eve->next){
+					if(eve->tmp.l == pathvert) eve->f |= SELECT;
+				}
+				pathvert = previous[pathvert];
+			}
+			
+			for(currpn=S.first; currpn; currpn=currpn->next) BLI_freelistN(&(currpn->edges));
+			BLI_freelistN(&S);
+			MEM_freeN(d);
+			MEM_freeN(previous);
+			
+			EM_select_flush();
+			
+		}
+	}
+}
+
 
 

source/blender/src/editobject.c

@@ -2089,7 +2089,7 @@ void special_editmenu(void)
 	}
 	else if(G.obedit->type==OB_MESH) {
 
-		nr= pupmenu("Specials%t|Subdivide%x1|Subdivide Multi%x2|Subdivide Multi Fractal%x3|Subdivide Smooth%x12|Merge%x4|Remove Doubles%x5|Hide%x6|Reveal%x7|Select Swap%x8|Flip Normals %x9|Smooth %x10|Bevel %x11|Set Smooth %x14|Set Solid %x15|Blend From Shape%x16|Propagate To All Shapes%x17");
+		nr= pupmenu("Specials%t|Subdivide%x1|Subdivide Multi%x2|Subdivide Multi Fractal%x3|Subdivide Smooth%x12|Merge%x4|Remove Doubles%x5|Hide%x6|Reveal%x7|Select Swap%x8|Flip Normals %x9|Smooth %x10|Bevel %x11|Set Smooth %x14|Set Solid %x15|Blend From Shape%x16|Propagate To All Shapes%x17| Path Select%x18");
 		
 		switch(nr) {
 		case 1:
@@ -2163,6 +2163,10 @@ void special_editmenu(void)
 		case 17: 
 			shape_propagate();
 			break;
+		case 18:
+			pathselect();
+			BIF_undo_push("Path Select");
+			break;
 		}
 		
 		DAG_object_flush_update(G.scene, G.obedit, OB_RECALC_DATA);