Add method which draws the normals of a mesh buffer. Mainly for debug purposes.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@4025 dfc29bdd-3216-0410-991c-e03cc46cb475

include/IVideoDriver.h

@@ -1015,9 +1015,16 @@ namespace video
 			video::SColor rightDownEdge = video::SColor(255,0,0,0)) =0;
 
 		//! Draws a mesh buffer
-		/** \param mb Buffer to draw; */
+		/** \param mb Buffer to draw */
 		virtual void drawMeshBuffer(const scene::IMeshBuffer* mb) =0;
 
+		//! Draws normals of a mesh buffer
+		/** \param mb Buffer to draw the normals of
+		\param length length scale factor of the normals
+		\param color Color the normals are rendered with
+		*/
+		virtual void drawMeshBufferNormals(const scene::IMeshBuffer* mb, f32 length=10.f, SColor color=0xffffffff) =0;
+
 		//! Sets the fog mode.
 		/** These are global values attached to each 3d object rendered,
 		which has the fog flag enabled in its material.

source/Irrlicht/CNullDriver.cpp

@@ -1520,6 +1520,24 @@ void CNullDriver::drawMeshBuffer(const scene::IMeshBuffer* mb)
 }
 
 
+//! Draws the normals of a mesh buffer
+void CNullDriver::drawMeshBufferNormals(const scene::IMeshBuffer* mb, f32 length, SColor color)
+{
+	const u32 count = mb->getVertexCount();
+	const bool normalize = mb->getMaterial().NormalizeNormals;
+
+	for (u32 i=0; i < count; ++i)
+	{
+		core::vector3df normalizedNormal = mb->getNormal(i);
+		if (normalize)
+			normalizedNormal.normalize();
+
+		const core::vector3df& pos = mb->getPosition(i);
+		draw3DLine(pos, pos + (normalizedNormal * length), color);
+	}
+}
+
+
 CNullDriver::SHWBufferLink *CNullDriver::getBufferLink(const scene::IMeshBuffer* mb)
 {
 	if (!mb || !isHardwareBufferRecommend(mb))

source/Irrlicht/CNullDriver.h

@@ -372,6 +372,9 @@ namespace video
 		//! Draws a mesh buffer
 		virtual void drawMeshBuffer(const scene::IMeshBuffer* mb);
 
+		//! Draws the normals of a mesh buffer
+		virtual void drawMeshBufferNormals(const scene::IMeshBuffer* mb, f32 length=10.f, SColor color=0xffffffff);
+
 	protected:
 		struct SHWBufferLink
 		{