Merge branch 'master' into patch-3

doc/dox.h

@@ -561,17 +561,27 @@ The output UV coordinate system has its origin in the lower-left corner:
 @endcode
 Use the #aiProcess_FlipUVs flag to get UV coordinates with the upper-left corner als origin.
 
-All matrices in the library are row-major. That means that the matrices are stored row by row in memory,
-which is similar to the OpenGL matrix layout. A typical 4x4 matrix including a translational part looks like this:
+A typical 4x4 matrix including a translational part looks like this:
 @code
 X1  Y1  Z1  T1
 X2  Y2  Z2  T2
 X3  Y3  Z3  T3
-0   0   0   1
+ 0   0   0   1
 @endcode
-with (X1, X2, X3) being the X base vector, (Y1, Y2, Y3) being the Y base vector, (Z1, Z2, Z3)
-being the Z base vector and (T1, T2, T3) being the translation part. If you want to use these matrices
-in DirectX functions, you have to transpose them.
+with <tt>(X1, X2, X3)</tt> being the local X base vector, <tt>(Y1, Y2, Y3)</tt> being the local
+Y base vector, <tt>(Z1, Z2, Z3)</tt> being the local Z base vector and <tt>(T1, T2, T3)</tt> being the
+offset of the local origin (the translational part). 
+All matrices in the library use row-major storage order. That means that the matrix elements are
+stored row-by-row, i.e. they end up like this in memory: 
+<tt>[X1, Y1, Z1, T1, X2, Y2, Z2, T2, X3, Y3, Z3, T3, 0, 0, 0, 1]</tt>. 
+
+Note that this is neither the OpenGL format nor the DirectX format, because both of them specify the
+matrix layout such that the translational part occupies three consecutive addresses in memory (so those
+matrices end with <tt>[..., T1, T2, T3, 1]</tt>), whereas the translation in an Assimp matrix is found at
+the offsets 3, 7 and 11 (spread across the matrix). You can transpose an Assimp matrix to end up with
+the format that OpenGL and DirectX mandate. To be very precise: The transposition has nothing
+to do with a left-handed or right-handed coordinate system but 'converts' between row-major and
+column-major storage format.
 
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