IMeshManipulator::transform can now also normalize normals

Also only update normals now using inner 3x3 matrix (same result usually as last column is 0,0,0 but faster)
And adding some comments.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@6419 dfc29bdd-3216-0410-991c-e03cc46cb475

include/IMeshManipulator.h

@@ -103,7 +103,9 @@ namespace scene
 				bool angleWeighted=false) const=0;
 
 		//! Scales the actual mesh, not a scene node.
-		/** \param mesh Mesh on which the operation is performed.
+		/** Note: When your scale are not uniform then
+		prefer the transform function to have correct normals.
+		\param mesh Mesh on which the operation is performed.
 		\param factor Scale factor for each axis. */
 		void scale(IMesh* mesh, const core::vector3df& factor) const
 		{
@@ -111,7 +113,9 @@ namespace scene
 		}
 
 		//! Scales the actual meshbuffer, not a scene node.
-		/** \param buffer Meshbuffer on which the operation is performed.
+		/** Note: When your scale are not uniform then
+		prefer the transform function to have correct normals.
+		\param buffer Meshbuffer on which the operation is performed.
 		\param factor Scale factor for each axis. */
 		void scale(IMeshBuffer* buffer, const core::vector3df& factor) const
 		{
@@ -146,9 +150,12 @@ namespace scene
 		/** \param mesh Mesh on which the operation is performed.
 		\param m transformation matrix. 
 		\param normalsUpdate When 0 - don't update normals. 
-		                     When 1 - update normals with inverse transposed of the transformation matrix
+		                     When 1 - update normals with inner 3x3 matrix of the inverse transposed of the transformation matrix
+							          should be set when the matrix has some non-uniform scaling
+		\param normalizeNormals When true it normalizes all normals again. 
+		                        Usually makes sense to set this as well when normalsUpdate is 1
 		*/
-		void transform(IMesh* mesh, const core::matrix4& m, u32 normalsUpdate = 0) const
+		void transform(IMesh* mesh, const core::matrix4& m, u32 normalsUpdate = 0, bool normalizeNormals=false) const
 		{
 			apply(SVertexPositionTransformManipulator(m), mesh, true);
 
@@ -158,18 +165,25 @@ namespace scene
 				if ( m.getInverse(invT) )
 				{
 					invT = invT.getTransposed();
-					apply(SVertexNormalTransformManipulator(invT), mesh, false);
+					apply(SVertexNormalRotateScaleManipulator(invT), mesh, false);
 				}
 			}
+			if ( normalizeNormals )
+			{
+				apply(SVertexNormalizeNormalManipulator(), mesh, false);
+			}
 		}
 
 		//! Applies a transformation to a meshbuffer
 		/** \param buffer Meshbuffer on which the operation is performed.
 		\param m transformation matrix. 
 		\param normalsUpdate When 0 - don't update normals. 
-		                     When 1 - update normals with inverse transposed of the transformation matrix
+		                     When 1 - update normals with inner 3x3 matrix of the inverse transposed of the transformation matrix
+							          should be set when the matrix has some non-uniform scaling
+		\param normalizeNormals When true it normalizes all normals again. 
+		                        Usually makes sense to set this as well when normalsUpdate is 1
 		*/
-		void transform(IMeshBuffer* buffer, const core::matrix4& m, u32 normalsUpdate = 0) const
+		void transform(IMeshBuffer* buffer, const core::matrix4& m, u32 normalsUpdate = 0, bool normalizeNormals=false) const
 		{
 			apply(SVertexPositionTransformManipulator(m), buffer, true);
 
@@ -179,9 +193,13 @@ namespace scene
 				if ( m.getInverse(invT) )
 				{
 					invT = invT.getTransposed();
-					apply(SVertexNormalTransformManipulator(invT), buffer, false);
+					apply(SVertexNormalRotateScaleManipulator(invT), buffer, false);
 				}
 			}
+			if ( normalizeNormals )
+			{
+				apply(SVertexNormalizeNormalManipulator(), buffer, false);
+			}
 		}
 
 		//! Applies a transformation to a mesh

include/SVertexManipulator.h

@@ -277,6 +277,32 @@ namespace scene
 		core::matrix4 Transformation;
 	};
 
+	//! Vertex manipulator which transforms the normal of the vertex with the rotate/scale part of the given matrix (inner 3x3)
+	class SVertexNormalRotateScaleManipulator : public IVertexManipulator
+	{
+	public:
+		SVertexNormalRotateScaleManipulator(const core::matrix4& m) : Transformation(m) {}
+		template <typename VType>
+		void operator()(VType& vertex) const
+		{
+			Transformation.rotateVect(vertex.Normal);
+		}
+	private:
+		core::matrix4 Transformation;
+	};
+
+	//! Vertex manipulator which normalizes the normal of the vertex
+	class SVertexNormalizeNormalManipulator : public IVertexManipulator
+	{
+	public:
+		SVertexNormalizeNormalManipulator() {}
+		template <typename VType>
+		void operator()(VType& vertex) const
+		{
+			vertex.Normal.normalize();
+		}
+	};
+
 	//! Vertex manipulator which scales the TCoords of the vertex
 	class SVertexTCoordsScaleManipulator : public IVertexManipulator
 	{

include/matrix4.h

@@ -221,10 +221,10 @@ namespace core
 			//! Translate a vector by the inverse of the translation part of this matrix.
 			void inverseTranslateVect( vector3df& vect ) const;
 
-			//! Rotate a vector by the inverse of the rotation part of this matrix.
+			//! Tranform (rotate/scale) a vector by the inverse of the rotation part this matrix
 			void inverseRotateVect( vector3df& vect ) const;
 
-			//! Rotate a vector by the rotation part of this matrix.
+			//! Transform (rotate/scale) a vector by the rotation part of this matrix.
 			void rotateVect( vector3df& vect ) const;
 
 			//! An alternate transform vector method, writing into a second vector