added individual polygon surface area calculation method to AC3D Model class

applications/SoundFieldSimulation/Raven/AC3D/itaAc3dModel.m

@@ -339,6 +339,47 @@ classdef itaAc3dModel
             S = obj.totalSurface;
         end
         
+        
+        function [surfacePolygons, surfacePolygonsMaterial] = getSurfacePolygons(obj)
+            % Calculate the surface area of individual mesh polygons.
+            % First return value is the surface of all polygons. Second
+            % return value is the surface of all polygons grouped by their
+            % assigned materials.
+            triaID = 1;
+            for matID = 1:length(obj.bcGroups)
+                for polyID = 1:length(obj.bcGroups{matID}.polygons)
+                    for vertID = 1:(length(obj.bcGroups{matID}.polygons{polyID}(:,1))-2)
+                        
+                        node1 = obj.nodes(obj.bcGroups{matID}.polygons{polyID}(1       ),:);
+                        node2 = obj.nodes(obj.bcGroups{matID}.polygons{polyID}(vertID+1),:);
+                        node3 = obj.nodes(obj.bcGroups{matID}.polygons{polyID}(vertID+2),:);
+                        
+                        % Dreieck nach Triangulation abspeichern
+                        triangles{triaID} = [node1;node2;node3];
+                        
+                        % Fl?chenberechnung f?r Dreieck
+                        a = norm( node1  - node2 );
+                        b = norm( node1  - node3 );
+                        c = norm( node2  - node3 );
+                        surfPoly = real( 1/4 * sqrt( (a+b+c) * (-a+b+c) * (a-b+c) * (a+b-c) ) );
+                        surfacePolygons(triaID) = surfPoly;
+                        surfacePolygonsMaterial{matID}(polyID) = surfPoly;
+                        
+                        % Normalenberechnung f?r Dreieck
+                        if norm( cross( (node2-node1), (node3-node1) ) ) == 0 % Schutz gegen Kr?ppel Linien Polygone
+                            normals{triaID} = [0 0 0];
+                        else
+                            normals{triaID} = cross( (node2-node1), (node3-node1) ) / norm( cross( (node2-node1), (node3-node1) ) );
+                        end
+                        
+                        % Index inkrement
+                        triaID = triaID+1;
+                    end
+                end
+            end
+        end
+        
+        
         function SMat = getMaterialSurface(obj,materialName)
             
              % sometimes multiple materials with the same name are defined. in this case, sum up all of them