patch index buffer for regular meshes

QTProject/subdivision.cpp

@@ -358,9 +358,221 @@ Subdivision::Tables Subdivision::precomputeTables(Input input) {
         }
     }
     qDebug()<<"Precompute Tables Done";
+    getPatchIndexBuffer(ib);
     return tables;
 }
 
+QVector<unsigned int> Subdivision::getPatchIndexBuffer(QVector<unsigned int> ib){
+    QVector<unsigned int> pib;
+    for (int i = 0; i < ib.length() - 2; i+=3){
+
+        unsigned int i0, i1, i2, i3, i4, i5, i6, i7, i8, i9, i10, i11;
+
+        //alles gegen den uzs
+        i3 = ib[i];
+        i6 = ib[i+1];
+        i7 = ib[i+2];
+
+        int count3 = 0; //counts other triangles with this vertex
+        int count6 = 0;
+        int count7 = 0;
+
+        for (int j = 0; j < ib.length(); j++){
+            if (j != i && j != i+1 && j != i+2){
+                //for debugging // checking if patch is regular.
+                if (ib[j] == i3) count3++;
+                if (ib[j] == i6) count6++;
+                if (ib[j] == i7) count7++;
+            }
+        }
+        if (count3 != 5 || count6 != 5 || count7 != 5){
+            qWarning()<<"Counts wrong! 3: "<< count3 <<", 6: "<<count6<<", 7: "<<count7;
+        }
+
+
+        //find triangles with shared edge. Fills i2, i4, i10.
+        {
+            bool found36 = false;
+            bool found67 = false;
+            bool found73 = false;
+            for (int j = 0; j < ib.length() - 2; j+=3){
+                unsigned int j0 = ib[j];
+                unsigned int j1 = ib[j+1];
+                unsigned int j2 = ib[j+2];
+
+                //Dreieck angrenzend an Kante i3 i6
+                if (j0 == i3 && j2 == i6){
+                    i2 = j1;
+                    found36 = true;
+                }
+                if (j1 == i3 && j0 == i6){
+                    i2 = j2;
+                    found36 = true;
+                }
+                if (j2 == i3 && j1 == i6){
+                    i2 == j0;
+                    found36 = true;
+                }
+
+                //Dreieck angrenzend an Kante i6 i7
+                if (j0 == i6 && j2 == i7){
+                    i10 = j1;
+                    found67 = true;
+                }
+                if (j1 == i6 && j0 == i7){
+                    i10 = j2;
+                    found67 = true;
+                }
+                if (j2 == i6 && j1 == i7){
+                    i10 = j0;
+                    found67 = true;
+                }
+
+                //Dreieck angrenzend an Kante i7 i3
+                if (j0 == i7 && j2 == i3){
+                    i4 = j1;
+                    found73 = true;
+                }
+                if (j1 == i7 && j0 == i3){
+                    i4 == j2;
+                    found73 = true;
+                }
+                if (j2 == i7 && j1 == i3){
+                    i4 = j0;
+                    found73 = true;
+                }
+            }
+
+            if (!(found36 && found67 && found73)){
+                qWarning()<<"Didnt find neighbour. duplicate vertex? Abort.";
+                return pib;
+            }
+        }
+
+
+        //find last missing triangles.
+        {
+            bool found0,found1,found5,found9,found8,found11;
+            for (int j = 0; j < ib.length() - 2; j+=3){
+                unsigned int j0 = ib[j];
+                unsigned int j1 = ib[j+1];
+                unsigned int j2 = ib[j+2];
+
+                //find i0. //TODO assert triangle 031 \exists somewhere
+                if (j0 == i2 && j1 == i3){
+                    i0 == j2;
+                    found0 = true;
+                }
+                if (j1 == i2 && j2 == i3){
+                    i0 = j0;
+                    found0 = true;
+                }
+                if (j2 == i2 && j0 == i3){
+                    i0 = j1;
+                    found0 = true;
+                }
+
+                //find i1
+                if (j0 == i3 && j1 == i4){
+                    i1 = j2;
+                    found1 = true;
+                }
+                if (j1 == i3 && j2 == i4){
+                    i1 = j0;
+                    found1 = true;
+                }
+                if (j2 == i3 && j0 == i4){
+                    i1 = j1;
+                    found1 = true;
+                }
+
+                //TODO maybe assert that triangle i0 i3 i1 actually \exists.
+
+                //find i5.
+                if(j0 == i6 && j1 == i2){
+                    i5 = j2;
+                    found5 = true;
+                }
+                if (j1 == i6 && j2 == i2){
+                    i5 = j0;
+                    found5 = true;
+                }
+                if (j2 == i6 && j0 == i2){
+                    i5 = j1;
+                    found5 = true;
+                }
+
+                //find i9.
+                if (j0 == i10 && j1 == i6){
+                    i9 = j2;
+                    found9 = true;
+                }
+                if (j1 == i10 && j2 == i6){
+                    i9 = j0;
+                    found9 = true;
+                }
+                if (j2 == i10 && j0 == i6){
+                    i9 = j1;
+                    found9 = true;
+                }
+
+                //todo assert that triangle i5 i9 i6
+
+
+                //find i8
+                if (j0 == i4 && j1 == i7){
+                    i8 = j2;
+                    found8 = true;
+                }
+                if (j1 == i4 && j2 == i7){
+                    i8 = j0;
+                    found8 = true;
+                }
+                if (j2 == i4 && j0 == i7){
+                    i8 = j1;
+                    found8 = true;
+                }
+
+                //find i11
+                if (j0 == i7 && j1 == i10){
+                    i11 = j2;
+                    found11 = true;
+                }
+                if (j1 == i7 && j2 == i10){
+                    i11 = j0;
+                    found11 = true;
+                }
+                if (j2 == i7 && j0 == i10){
+                    i11 = j1;
+                    found11 = true;
+                }
+            }
+            if (!(found0 && found1 && found5 && found9 && found8 && found11)){
+                qWarning()<<"Couldnt find some neighbour at i= "<<i;
+                qWarning()<<found0<<found1<<found5<<found9<<found8<<found11;
+                qWarning()<<"Abort computing patch index buffer.";
+                return pib;
+            }
+            //else qWarning()<<"found all neighbours for patch.";
+            pib.push_back(i0);
+            pib.push_back(i1);
+            pib.push_back(i2);
+            pib.push_back(i3);
+            pib.push_back(i4);
+            pib.push_back(i5);
+            pib.push_back(i6);
+            pib.push_back(i7);
+            pib.push_back(i8);
+            pib.push_back(i9);
+            pib.push_back(i10);
+            pib.push_back(i11);
+         }
+    }
+
+    return pib;
+
+}
+
 Subdivision::Result Subdivision::runShader(Input input, Tables &tables) {
     qDebug()<<"Running compute shader";
 

QTProject/subdivision.h

@@ -50,6 +50,9 @@ private:
     void runVertexShader(GLuint size, GLuint vb_handle, GLuint vertex_indices_handle, GLuint vertex_offsets_handle, GLuint output_handle);
     void runEdgeShader(GLuint size, GLuint vb_handle, GLuint edge_indices_handle, GLuint output_handle, GLuint offset);
 
+    //Geht davon aus, dass jeder 3D-Punkt nur einmal im Vertex-Buffer vorkommt!
+    QVector<unsigned int> getPatchIndexBuffer(QVector<unsigned int> ib);
+
 };
 
 #endif