Compute edge points in order xy, yz, zx (vertex 0-vertex1, vertex1-vertex2, vertex2-vertex0).

QTProject/subdivision.cpp

@@ -82,58 +82,107 @@ void Subdivision::precomputeTables(Mesh *mesh) {
         unsigned int x_i = ib[i];
         unsigned int y_i = ib[i+1];
         unsigned int z_i = ib[i+2];
+
+        //get vertices x,y,z from vertex buffer
         x = vb[x_i];//todo maybe check array length
         y = vb[y_i];
         z = vb[z_i];
 
-        //get vertices x,y,z from vertex buffer
 
-        for (int j = i+3; j < ib.length(); j+= 3){
-            //search all following triangles for common edge
-            Vertex a,b,c;
-            unsigned int a_i, b_i, c_i;
-            a_i = ib[j];
-            b_i = ib[j+1];
-            c_i = ib[j+2];
-
-            a = vb[a_i];
-            b = vb[b_i];
-            c = vb[c_i];
-
-            //get vertices for a,b,c from vertex buffer
-            //comparisons: xy = ba, cb, ac.
-            //yz = ba, cb, ac
-            //zx = ba, cb, ac
-            //TODO if oder else if?
-            if (x.samePos(a) && y.samePos(c)){
-                edgeIndices_base.push_back(fillVector(x_i,y_i,z_i,b_i));
-            }
-            if (x.samePos(a) && z.samePos(b)){
-                edgeIndices_base.push_back(fillVector(x_i,z_i,y_i,c_i));
-            }
-            if (x.samePos(b) && y.samePos(a)){
-                edgeIndices_base.push_back(fillVector(x_i,y_i,z_i,c_i));
-            }
-            if (x.samePos(b) && z.samePos(c)){
-                edgeIndices_base.push_back(fillVector(x_i,z_i,y_i,a_i));
-            }
-            if (x.samePos(c) && y.samePos(b)){
-                edgeIndices_base.push_back(fillVector(x_i,y_i,z_i,a_i));
-            }
-            if (x.samePos(c) && z.samePos(a)){
-                edgeIndices_base.push_back(fillVector(x_i,z_i,y_i,b_i));
+        /*
+         * Find edge xy in all other triangles, add to edgeIndices_base
+         * Find edge yz
+         * Find edge zx
+         * - We assume that we have a closed surface, i.e. each triangle has exactly one adjacent triangle at each edge
+         * - Each edge point will be computed twice. This allows us to implicitly know the adjacent points.
+         */
+
+        //find indices for edge point on xy-edge
+        for (int j = 0; j < ib.length(); j+= 3){
+            if (j != i){
+                //search all following triangles for common edge
+                Vertex a,b,c;
+                unsigned int a_i, b_i, c_i;
+                a_i = ib[j];
+                b_i = ib[j+1];
+                c_i = ib[j+2];
+
+                a = vb[a_i];
+                b = vb[b_i];
+                c = vb[c_i];
+
+                //get vertices for a,b,c from vertex buffer
+                //comparisons: xy = ba, cb, ac.
+                //yz = ba, cb, ac
+                //zx = ba, cb, ac
+                //TODO if oder else if?
+                if (x.samePos(a) && y.samePos(c)){
+                    edgeIndices_base.push_back(fillVector(x_i,y_i,z_i,b_i));
+                }
+                if (x.samePos(b) && y.samePos(a)){
+                    edgeIndices_base.push_back(fillVector(x_i,y_i,z_i,c_i));
+                }
+                if (x.samePos(c) && y.samePos(b)){
+                    edgeIndices_base.push_back(fillVector(x_i,y_i,z_i,a_i));
+                }
             }
+        }
 
-            if (y.samePos(a) && z.samePos(c)){
-                edgeIndices_base.push_back(fillVector(y_i,z_i,x_i,b_i));
-            }
-            if (y.samePos(b) && z.samePos(a)){
-                edgeIndices_base.push_back(fillVector(y_i,z_i,x_i,c_i));
+        //find indices for edge point on yz-edge
+        for (int j = 0; j < ib.length(); j+= 3){
+            if (j != i){
+                //search all following triangles for common edge
+                Vertex a,b,c;
+                unsigned int a_i, b_i, c_i;
+                a_i = ib[j];
+                b_i = ib[j+1];
+                c_i = ib[j+2];
+
+                a = vb[a_i];
+                b = vb[b_i];
+                c = vb[c_i];
+
+                //yz = ba, cb, ac
+                if (y.samePos(a) && z.samePos(c)){
+                    edgeIndices_base.push_back(fillVector(y_i,z_i,x_i,b_i));
+                }
+                if (y.samePos(b) && z.samePos(a)){
+                    edgeIndices_base.push_back(fillVector(y_i,z_i,x_i,c_i));
+                }
+                if (y.samePos(c) && z.samePos(b)){
+                    edgeIndices_base.push_back(fillVector(y_i,z_i,x_i,a_i));
+                }
             }
-            if (y.samePos(c) && z.samePos(b)){
-                edgeIndices_base.push_back(fillVector(y_i,z_i,x_i,a_i));
+        }
+
+
+        //find indices for edge point on xy-edge
+        for (int j = 0; j < ib.length(); j+= 3){
+            if (j != i){
+                //search all following triangles for common edge
+                Vertex a,b,c;
+                unsigned int a_i, b_i, c_i;
+                a_i = ib[j];
+                b_i = ib[j+1];
+                c_i = ib[j+2];
+
+                a = vb[a_i];
+                b = vb[b_i];
+                c = vb[c_i];
+
+
+                if (x.samePos(a) && z.samePos(b)){
+                    edgeIndices_base.push_back(fillVector(x_i,z_i,y_i,c_i));
+                }
+                if (x.samePos(b) && z.samePos(c)){
+                    edgeIndices_base.push_back(fillVector(x_i,z_i,y_i,a_i));
+                }
+                if (x.samePos(c) && z.samePos(a)){
+                    edgeIndices_base.push_back(fillVector(x_i,z_i,y_i,b_i));
+                }
             }
         }//quadratische Laufzeit ftw
+       //Wichtig: Wir gehen davon aus, dass wir geschlossene Oberflächen haben, dh für jede Kante von einem Dreieck wird eine passende Kante bei einem anderen Dreieck gefunden.
     }
 
     qDebug()<<"Done with edge table. "<<edgeIndices_base.length()<<" edges found. Table: "<<edgeIndices_base;