Added "FixNormals"-Step.

git-svn-id: https://assimp.svn.sourceforge.net/svnroot/assimp/trunk@88 67173fc5-114c-0410-ac8e-9d2fd5bffc1f

code/FixNormalsStep.cpp

@@ -0,0 +1,172 @@
+/*
+---------------------------------------------------------------------------
+Open Asset Import Library (ASSIMP)
+---------------------------------------------------------------------------
+
+Copyright (c) 2006-2008, ASSIMP Development Team
+
+All rights reserved.
+
+Redistribution and use of this software in source and binary forms, 
+with or without modification, are permitted provided that the following 
+conditions are met:
+
+* Redistributions of source code must retain the above
+  copyright notice, this list of conditions and the
+  following disclaimer.
+
+* Redistributions in binary form must reproduce the above
+  copyright notice, this list of conditions and the
+  following disclaimer in the documentation and/or other
+  materials provided with the distribution.
+
+* Neither the name of the ASSIMP team, nor the names of its
+  contributors may be used to endorse or promote products
+  derived from this software without specific prior
+  written permission of the ASSIMP Development Team.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+---------------------------------------------------------------------------
+*/
+
+/** @file Implementation of the post processing step to invert
+ * all normals in meshes with infacing normals.
+ */
+
+// CRT includes
+#include <vector>
+#include <assert.h>
+
+// internal headers
+#include "FixNormalsStep.h"
+#include "SpatialSort.h"
+
+// public ASSIMP headers
+#include "../include/DefaultLogger.h"
+#include "../include/aiPostProcess.h"
+#include "../include/aiMesh.h"
+#include "../include/aiScene.h"
+
+using namespace Assimp;
+
+// ------------------------------------------------------------------------------------------------
+// Constructor to be privately used by Importer
+FixInfacingNormalsProcess::FixInfacingNormalsProcess()
+{
+	// nothing to do here
+}
+
+// ------------------------------------------------------------------------------------------------
+// Destructor, private as well
+FixInfacingNormalsProcess::~FixInfacingNormalsProcess()
+{
+	// nothing to do here
+}
+
+// ------------------------------------------------------------------------------------------------
+// Returns whether the processing step is present in the given flag field.
+bool FixInfacingNormalsProcess::IsActive( unsigned int pFlags) const
+{
+	return (pFlags & aiProcess_FixInfacingNormals) != 0;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Executes the post processing step on the given imported data.
+void FixInfacingNormalsProcess::Execute( aiScene* pScene)
+{
+	DefaultLogger::get()->debug("FixInfacingNormalsProcess begin");
+
+	bool bHas = false;
+	for( unsigned int a = 0; a < pScene->mNumMeshes; a++)
+		if(ProcessMesh( pScene->mMeshes[a]))bHas = true;
+
+	if (bHas)DefaultLogger::get()->debug("FixInfacingNormalsProcess finished. At least one mesh' normals have been flipped.");
+	else DefaultLogger::get()->debug("FixInfacingNormalsProcess finished");
+}
+
+// ------------------------------------------------------------------------------------------------
+// Apply the step to the mesh
+bool FixInfacingNormalsProcess::ProcessMesh( aiMesh* pcMesh)
+{
+	ai_assert(NULL != pcMesh);
+
+	if (!pcMesh->HasNormals())return false;
+
+	// compute the bounding box of both the model vertices + normals and
+	// the umodified model vertices. Then check whether the first BB
+	// is smaller than the second. In this case we can assume that the
+	// normals need to be flipped, although there are a few special cases ..
+	// convex, concave, planar models ...
+
+	aiVector3D vMin0(1e10f,1e10f,1e10f);
+	aiVector3D vMin1(1e10f,1e10f,1e10f);
+	aiVector3D vMax0(-1e10f,-1e10f,-1e10f);
+	aiVector3D vMax1(-1e10f,-1e10f,-1e10f);
+
+	for (unsigned int i = 0; i < pcMesh->mNumVertices;++i)
+	{
+		vMin1.x = std::min(vMin1.x,pcMesh->mVertices[i].x);
+		vMin1.y = std::min(vMin1.y,pcMesh->mVertices[i].y);
+		vMin1.z = std::min(vMin1.z,pcMesh->mVertices[i].z);
+
+		vMax1.x = std::max(vMax1.x,pcMesh->mVertices[i].x);
+		vMax1.y = std::max(vMax1.y,pcMesh->mVertices[i].y);
+		vMax1.z = std::max(vMax1.z,pcMesh->mVertices[i].z);
+
+		aiVector3D vWithNormal = pcMesh->mVertices[i] + pcMesh->mNormals[i];
+
+		vMin0.x = std::min(vMin0.x,vWithNormal.x);
+		vMin0.y = std::min(vMin0.y,vWithNormal.y);
+		vMin0.z = std::min(vMin0.z,vWithNormal.z);
+
+		vMax0.x = std::max(vMax0.x,vWithNormal.x);
+		vMax0.y = std::max(vMax0.y,vWithNormal.y);
+		vMax0.z = std::max(vMax0.z,vWithNormal.z);
+	}
+
+	const float fDelta0_x = (vMax0.x - vMin0.x);
+	const float fDelta0_y = (vMax0.y - vMin0.y);
+	const float fDelta0_z = (vMax0.z - vMin0.z);
+
+	const float fDelta1_x = (vMax1.x - vMin1.x);
+	const float fDelta1_y = (vMax1.y - vMin1.y);
+	const float fDelta1_z = (vMax1.z - vMin1.z);
+
+	// check the case where the boxes are overlapping
+	if (fDelta0_x > 0.0f != fDelta1_x > 0.0f)return false;
+	if (fDelta0_y > 0.0f != fDelta1_y > 0.0f)return false;
+	if (fDelta0_z > 0.0f != fDelta1_z > 0.0f)return false;
+
+
+	// check the case of a very planar surface
+	const float fDelta1_yz = fDelta1_y * fDelta1_z;
+
+	if (fDelta1_x < 0.05f * sqrtf( fDelta1_yz ))return false;
+	if (fDelta1_y < 0.05f * sqrtf( fDelta1_z * fDelta1_x ))return false;
+	if (fDelta1_z < 0.05f * sqrtf( fDelta1_y * fDelta1_x ))return false;
+
+	// now compare the volume of the bounding boxes
+	if (::fabsf(fDelta0_x * fDelta1_yz) <
+		::fabsf(fDelta1_x * fDelta1_y * fDelta1_z))
+	{
+		DefaultLogger::get()->info("Found a mesh whose normals are facing inwards "
+			"(or the model is too planar or concave). Flipping mesh normals ...");
+
+		for (unsigned int i = 0; i < pcMesh->mNumVertices;++i)
+		{
+			pcMesh->mNormals[i] *= -1.0f;
+		}
+		return true;
+	}
+	return false;
+}

code/FixNormalsStep.h

@@ -0,0 +1,96 @@
+/*
+Open Asset Import Library (ASSIMP)
+----------------------------------------------------------------------
+
+Copyright (c) 2006-2008, ASSIMP Development Team
+All rights reserved.
+
+Redistribution and use of this software in source and binary forms, 
+with or without modification, are permitted provided that the 
+following conditions are met:
+
+* Redistributions of source code must retain the above
+  copyright notice, this list of conditions and the
+  following disclaimer.
+
+* Redistributions in binary form must reproduce the above
+  copyright notice, this list of conditions and the
+  following disclaimer in the documentation and/or other
+  materials provided with the distribution.
+
+* Neither the name of the ASSIMP team, nor the names of its
+  contributors may be used to endorse or promote products
+  derived from this software without specific prior
+  written permission of the ASSIMP Development Team.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+----------------------------------------------------------------------
+*/
+
+
+/** @file Defines a post processing step to fix infacing normals */
+#ifndef AI_FIXNORMALSPROCESS_H_INC
+#define AI_FIXNORMALSPROCESS_H_INC
+
+#include "BaseProcess.h"
+
+struct aiMesh;
+
+namespace Assimp
+{
+
+// ---------------------------------------------------------------------------
+/** The FixInfacingNormalsProcess tries to deteermine whether the normal
+ * vectors of an object are facing inwards. In this case they will be
+ * flipped.
+ */
+class FixInfacingNormalsProcess : public BaseProcess
+{
+	friend class Importer;
+
+protected:
+	/** Constructor to be privately used by Importer */
+	FixInfacingNormalsProcess();
+
+	/** Destructor, private as well */
+	~FixInfacingNormalsProcess();
+
+public:
+	// -------------------------------------------------------------------
+	/** Returns whether the processing step is present in the given flag field.
+	 * @param pFlags The processing flags the importer was called with. A bitwise
+	 *   combination of #aiPostProcessSteps.
+	 * @return true if the process is present in this flag fields, false if not.
+	*/
+	bool IsActive( unsigned int pFlags) const;
+
+	// -------------------------------------------------------------------
+	/** Executes the post processing step on the given imported data.
+	* At the moment a process is not supposed to fail.
+	* @param pScene The imported data to work at.
+	*/
+	void Execute( aiScene* pScene);
+
+protected:
+
+	// -------------------------------------------------------------------
+	/** Executes the step on the given mesh
+	 * @param pMesh The mesh to process.
+	 */
+	bool ProcessMesh( aiMesh* pMesh);
+};
+
+} // end of namespace Assimp
+
+#endif // AI_FIXNORMALSPROCESS_H_INC