Change the triangle pattern used for terrain (Fixes #2459)

components/terrain/buffercache.cpp

@@ -58,6 +58,19 @@ Ogre::HardwareIndexBufferSharedPtr createIndexBuffer(unsigned int flags, unsigne
     for (size_t row = rowStart; row < rowEnd; row += increment)
     {
         for (size_t col = colStart; col < colEnd; col += increment)
+        {
+            // diamond pattern
+            if ((row + col%2) % 2 == 1)
+            {
+                indices.push_back(verts*(col+increment)+row);
+                indices.push_back(verts*(col+increment)+row+increment);
+                indices.push_back(verts*col+row+increment);
+
+                indices.push_back(verts*col+row);
+                indices.push_back(verts*(col+increment)+row);
+                indices.push_back(verts*(col)+row+increment);
+            }
+            else
             {
                 indices.push_back(verts*col+row);
                 indices.push_back(verts*(col+increment)+row+increment);
@@ -68,6 +81,7 @@ Ogre::HardwareIndexBufferSharedPtr createIndexBuffer(unsigned int flags, unsigne
                 indices.push_back(verts*(col+increment)+row+increment);
             }
         }
+    }
 
     size_t innerStep = increment;
     if (anyDeltas)