ENH: Improved code comments for triangle intersection area calc

src/meshTools/AMIInterpolation/faceAreaIntersect/faceAreaIntersect.C

@@ -53,9 +53,9 @@ void Foam::faceAreaIntersect::triSliceWithPlane
 
         if (mag(d[i]) < matchTol*len)
         {
-            d[i] = 0.0;
             nCoPlanar++;
             copI = i;
+            d[i] = 0.0;
         }
         else
         {
@@ -71,6 +71,9 @@ void Foam::faceAreaIntersect::triSliceWithPlane
         }
     }
 
+
+    // Determine triangle area contribution
+
     if
     (
         (nPos == 3)
@@ -78,6 +81,12 @@ void Foam::faceAreaIntersect::triSliceWithPlane
      || ((nPos == 1) && (nCoPlanar == 2)))
     {
         // all points above cutting plane - add triangle to list
+
+        //        /\          _____                
+        //       /  \         \   /          /\
+        //      /____\         \ /          /  \   
+        //    __________    ____v____    __/____\__
+
         tris[nTris++] = tri;
     }
     else if ((nPos == 2) && (nCoPlanar == 0))
@@ -85,6 +94,12 @@ void Foam::faceAreaIntersect::triSliceWithPlane
         // 2 points above plane, 1 below
         // resulting quad above plane split into 2 triangles
 
+        //     ________
+        //     \      /
+        //    --\----/--
+        //       \  /
+        //        \/
+
         // point under the plane
         label i0 = negI;
 
@@ -110,6 +125,11 @@ void Foam::faceAreaIntersect::triSliceWithPlane
         {
             // 1 point above plane, 2 below
 
+            //        /\
+            //       /  \
+            //    --/----\--
+            //     /______\
+
             // indices of remaining points
             label i1 = d.fcIndex(i0);
             label i2 = d.fcIndex(i1);
@@ -126,6 +146,13 @@ void Foam::faceAreaIntersect::triSliceWithPlane
         {
             // 1 point above plane, 1 on plane, 1 below
 
+            //      |\
+            //      | \
+            //    __|__\__
+            //      |  /
+            //      | /
+            //      |/
+
             // point indices
             label i1 = negI;
             label i2 = copI;
@@ -147,6 +174,13 @@ void Foam::faceAreaIntersect::triSliceWithPlane
     else
     {
         // all points below cutting plane - forget
+
+        //    _________    __________    ___________
+        //                     /\          \    /
+        //       /\           /  \          \  /
+        //      /  \         /____\          \/
+        //     /____\
+
     }
 }