用OpenSceneGraph实现的NeHe OpenGL教程 - 第三十一课

• 简介

本节课实现了加载Milkshape3D建模生成的文件，本课的大部分内容主要是分析Milkshape3D的模型文件格式

• 实现

本课中的读取文件的内容大部分来自NeHe课程中的代码：

主要加载文件的代码在以下函数之中：

virtual bool loadModelData( const char *filename )

其他的部分在前面课程中已经详细地介绍过了，具体读者可以查看代码：

编译运行程序：

附：本课源码（源码中可能存在错误和不足，仅供参考）

#include "../osgNeHe.h"

#include <iostream>
#include <fstream>

#include <QtCore/QTimer>
#include <QtGui/QApplication>
#include <QtGui/QVBoxLayout>

#include <osgViewer/Viewer>
#include <osgDB/ReadFile>
#include <osgQt/GraphicsWindowQt>

#include <osg/MatrixTransform>
#include <osg/Texture2D>
#include <osg/Material>
#include <osg/AnimationPath>
using namespace std;


//////////////////////////////////////////////////////////////////////////
///////////////File From NeHe Tutorial//////////////////////////
//////////////////////////////////////////////////////////////////////////

osg::Texture2D * LoadGLTexture( const char *filename )
{
	osg::Image *textureImage = osgDB::readImageFile(filename);
	osg::Texture2D *texture2D = new osg::Texture2D;
	texture2D->setImage(textureImage);
	texture2D->setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR);
	texture2D->setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR);

	return texture2D;
}

class Model
{
	public:
		struct Mesh
		{
			int m_materialIndex;
			int m_numTriangles;
			int *m_pTriangleIndices;
		};
		struct Material
		{
			float m_ambient[4], m_diffuse[4], m_specular[4], m_emissive[4];
			float m_shininess;
			osg::Texture2D *m_texture;
			char *m_pTextureFilename;
		};
		struct Triangle
		{
			float m_vertexNormals[3][3];
			float m_s[3], m_t[3];
			int m_vertexIndices[3];
		};
		struct Vertex
		{
			char m_boneID;
			float m_location[3];
		};

	public:
		Model()
		{
			m_numMeshes = 0;
			m_pMeshes = NULL;
			m_numMaterials = 0;
			m_pMaterials = NULL;
			m_numTriangles = 0;
			m_pTriangles = NULL;
			m_numVertices = 0;
			m_pVertices = NULL;
		}
		virtual ~Model()
		{
			int i;
			for ( i = 0; i < m_numMeshes; i++ )
				delete[] m_pMeshes[i].m_pTriangleIndices;
			for ( i = 0; i < m_numMaterials; i++ )
				delete[] m_pMaterials[i].m_pTextureFilename;

			m_numMeshes = 0;
			if ( m_pMeshes != NULL )
			{
				delete[] m_pMeshes;
				m_pMeshes = NULL;
			}

			m_numMaterials = 0;
			if ( m_pMaterials != NULL )
			{
				delete[] m_pMaterials;
				m_pMaterials = NULL;
			}

			m_numTriangles = 0;
			if ( m_pTriangles != NULL )
			{
				delete[] m_pTriangles;
				m_pTriangles = NULL;
			}

			m_numVertices = 0;
			if ( m_pVertices != NULL )
			{
				delete[] m_pVertices;
				m_pVertices = NULL;
			}
		}
		virtual bool loadModelData( const char *filename ) = 0;

		osg::Geode*	drawGeode()
		{
			osg::Geode *geode = new osg::Geode;
			geode->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF);

			for ( int i = 0; i < m_numMeshes; i++ )
			{
				osg::Geometry *geometry = new osg::Geometry;
				osg::Vec3Array *vertexArray = new osg::Vec3Array;
				osg::Vec2Array *textureArray = new osg::Vec2Array;
				osg::Vec3Array *normalArray = new osg::Vec3Array;

				int materialIndex = m_pMeshes[i].m_materialIndex;
				if ( materialIndex >= 0 )
				{
					osg::Material *material = new osg::Material;
					material->setAmbient(osg::Material::FRONT,osg::Vec4(m_pMaterials[materialIndex].m_ambient[0], m_pMaterials[materialIndex].m_ambient[1],m_pMaterials[materialIndex].m_ambient[2],m_pMaterials[materialIndex].m_ambient[3]));
					material->setDiffuse(osg::Material::FRONT,osg::Vec4(m_pMaterials[materialIndex].m_diffuse[0],m_pMaterials[materialIndex].m_diffuse[1],m_pMaterials[materialIndex].m_diffuse[2],m_pMaterials[materialIndex].m_diffuse[3]));
					material->setEmission(osg::Material::FRONT,osg::Vec4(m_pMaterials[materialIndex].m_emissive[0],m_pMaterials[materialIndex].m_emissive[1],m_pMaterials[materialIndex].m_emissive[2],m_pMaterials[materialIndex].m_emissive[3]));
					material->setSpecular(osg::Material::FRONT,osg::Vec4(m_pMaterials[materialIndex].m_specular[0],m_pMaterials[materialIndex].m_specular[1],m_pMaterials[materialIndex].m_specular[2],m_pMaterials[materialIndex].m_specular[3]));
					material->setShininess(osg::Material::FRONT, m_pMaterials[materialIndex].m_shininess);
					geometry->getOrCreateStateSet()->setAttributeAndModes(material);

					if ( m_pMaterials[materialIndex].m_texture > 0 )
					{
						geometry->getOrCreateStateSet()->setTextureAttributeAndModes(0, m_pMaterials[materialIndex].m_texture);
					}
				}

				for ( int j = 0; j < m_pMeshes[i].m_numTriangles; j++ )
				{
					int triangleIndex = m_pMeshes[i].m_pTriangleIndices[j];
					const Triangle* pTri = &m_pTriangles[triangleIndex];

					for ( int k = 0; k < 3; k++ )
					{
						int index = pTri->m_vertexIndices[k];
						normalArray->push_back(osg::Vec3(pTri->m_vertexNormals[k][0], pTri->m_vertexNormals[k][1], pTri->m_vertexNormals[k][2]));
						textureArray->push_back(osg::Vec2(pTri->m_s[k], pTri->m_t[k]));
						vertexArray->push_back(osg::Vec3(m_pVertices[index].m_location[0], m_pVertices[index].m_location[1], m_pVertices[index].m_location[2]));
					}
				}

				geometry->setVertexArray(vertexArray);
				geometry->setNormalArray(normalArray, osg::Array::BIND_PER_VERTEX);
				geometry->setTexCoordArray(0, textureArray, osg::Array::BIND_PER_VERTEX);
				geometry->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::TRIANGLES, 0, vertexArray->size()));

				geode->addDrawable(geometry);
			}

			return geode;
		}

		void reloadTextures()
		{
			for ( int i = 0; i < m_numMaterials; i++ )
				if ( strlen( m_pMaterials[i].m_pTextureFilename ) > 0 )
					m_pMaterials[i].m_texture = LoadGLTexture( m_pMaterials[i].m_pTextureFilename );
				else
					m_pMaterials[i].m_texture = 0;
		}
	protected:
		int m_numMeshes;
		Mesh *m_pMeshes;
		int m_numMaterials;
		Material *m_pMaterials;
		int m_numTriangles;
		Triangle *m_pTriangles;
		int m_numVertices;
		Vertex *m_pVertices;
};


//////////////////////////////////////////////////////////////////////////

#ifdef _MSC_VER
#	pragma pack( push, packing )
#	pragma pack( 1 )
#	define PACK_STRUCT
#elif defined( __GNUC__ )
#	define PACK_STRUCT	__attribute__((packed))
#else
#	error you must byte-align these structures with the appropriate compiler directives
#endif

typedef unsigned short word;

// File header
struct MS3DHeader
{
	char m_ID[10];
	int m_version;
} PACK_STRUCT;

// Vertex information
struct MS3DVertex
{
	char m_flags;
	float m_vertex[3];
	char m_boneID;
	char m_refCount;
} PACK_STRUCT;

// Triangle information
struct MS3DTriangle
{
	word m_flags;
	word m_vertexIndices[3];
	float m_vertexNormals[3][3];
	float m_s[3], m_t[3];
	char m_smoothingGroup;
	char m_groupIndex;
} PACK_STRUCT;

// Material information
struct MS3DMaterial
{
	char m_name[32];
	float m_ambient[4];
	float m_diffuse[4];
	float m_specular[4];
	float m_emissive[4];
	float m_shininess;	// 0.0f - 128.0f
	float m_transparency;	// 0.0f - 1.0f
	char m_mode;	// 0, 1, 2 is unused now
	char m_texture[128];
	char m_alphamap[128];
} PACK_STRUCT;

//	Joint information
struct MS3DJoint
{
	char m_flags;
	char m_name[32];
	char m_parentName[32];
	float m_rotation[3];
	float m_translation[3];
	word m_numRotationKeyframes;
	word m_numTranslationKeyframes;
} PACK_STRUCT;

// Keyframe data
struct MS3DKeyframe
{
	float m_time;
	float m_parameter[3];
} PACK_STRUCT;

// Default alignment
#ifdef _MSC_VER
#	pragma pack( pop, packing )
#endif

#undef PACK_STRUCT


class MilkshapeModel : public Model
{
	public:
		MilkshapeModel()
		{
		}
		virtual ~MilkshapeModel()
		{
		}
		virtual bool loadModelData( const char *filename )
		{
			ifstream inputFile( filename, ios::in | ios::binary | ios::_Nocreate );
			if ( inputFile.fail())
				return false;

			inputFile.seekg( 0, ios::end );
			long fileSize = inputFile.tellg();
			inputFile.seekg( 0, ios::beg );

			char *pBuffer = new char[fileSize];
			inputFile.read( pBuffer, fileSize );
			inputFile.close();

			const char *pPtr = pBuffer;
			MS3DHeader *pHeader = ( MS3DHeader* )pPtr;
			pPtr += sizeof( MS3DHeader );

			if ( strncmp( pHeader->m_ID, "MS3D000000", 10 ) != 0 )
				return false; // "Not a valid Milkshape3D model file."

			if ( pHeader->m_version < 3 || pHeader->m_version > 4 )
				return false; // "Unhandled file version. Only Milkshape3D Version 1.3 and 1.4 is supported." );

			int nVertices = *( word* )pPtr; 
			m_numVertices = nVertices;
			m_pVertices = new Vertex[nVertices];
			pPtr += sizeof( word );

			int i;
			for ( i = 0; i < nVertices; i++ )
			{
				MS3DVertex *pVertex = ( MS3DVertex* )pPtr;
				m_pVertices[i].m_boneID = pVertex->m_boneID;
				memcpy( m_pVertices[i].m_location, pVertex->m_vertex, sizeof( float )*3 );
				pPtr += sizeof( MS3DVertex );
			}

			int nTriangles = *( word* )pPtr;
			m_numTriangles = nTriangles;
			m_pTriangles = new Triangle[nTriangles];
			pPtr += sizeof( word );

			for ( i = 0; i < nTriangles; i++ )
			{
				MS3DTriangle *pTriangle = ( MS3DTriangle* )pPtr;
				int vertexIndices[3] = { pTriangle->m_vertexIndices[0], pTriangle->m_vertexIndices[1], pTriangle->m_vertexIndices[2] };
				float t[3] = { 1.0f-pTriangle->m_t[0], 1.0f-pTriangle->m_t[1], 1.0f-pTriangle->m_t[2] };
				memcpy( m_pTriangles[i].m_vertexNormals, pTriangle->m_vertexNormals, sizeof( float )*3*3 );
				memcpy( m_pTriangles[i].m_s, pTriangle->m_s, sizeof( float )*3 );
				memcpy( m_pTriangles[i].m_t, t, sizeof( float )*3 );
				memcpy( m_pTriangles[i].m_vertexIndices, vertexIndices, sizeof( int )*3 );
				pPtr += sizeof( MS3DTriangle );
			}

			int nGroups = *( word* )pPtr;
			m_numMeshes = nGroups;
			m_pMeshes = new Mesh[nGroups];
			pPtr += sizeof( word );
			for ( i = 0; i < nGroups; i++ )
			{
				pPtr += sizeof( char );	// flags
				pPtr += 32;				// name

				word nTriangles = *( word* )pPtr;
				pPtr += sizeof( word );
				int *pTriangleIndices = new int[nTriangles];
				for ( int j = 0; j < nTriangles; j++ )
				{
					pTriangleIndices[j] = *( word* )pPtr;
					pPtr += sizeof( word );
				}

				char materialIndex = *( char* )pPtr;
				pPtr += sizeof( char );

				m_pMeshes[i].m_materialIndex = materialIndex;
				m_pMeshes[i].m_numTriangles = nTriangles;
				m_pMeshes[i].m_pTriangleIndices = pTriangleIndices;
			}

			int nMaterials = *( word* )pPtr;
			m_numMaterials = nMaterials;
			m_pMaterials = new Material[nMaterials];
			pPtr += sizeof( word );
			for ( i = 0; i < nMaterials; i++ )
			{
				MS3DMaterial *pMaterial = ( MS3DMaterial* )pPtr;
				memcpy( m_pMaterials[i].m_ambient, pMaterial->m_ambient, sizeof( float )*4 );
				memcpy( m_pMaterials[i].m_diffuse, pMaterial->m_diffuse, sizeof( float )*4 );
				memcpy( m_pMaterials[i].m_specular, pMaterial->m_specular, sizeof( float )*4 );
				memcpy( m_pMaterials[i].m_emissive, pMaterial->m_emissive, sizeof( float )*4 );
				m_pMaterials[i].m_shininess = pMaterial->m_shininess;
				m_pMaterials[i].m_pTextureFilename = new char[strlen( pMaterial->m_texture )+1];
				strcpy( m_pMaterials[i].m_pTextureFilename, pMaterial->m_texture );
				pPtr += sizeof( MS3DMaterial );
			}

			reloadTextures();

			delete[] pBuffer;

			return true;
		}
};


class ViewerWidget : public QWidget, public osgViewer::Viewer
{
public:
	ViewerWidget(osg::Node *scene = NULL)
	{
		QWidget* renderWidget = getRenderWidget( createGraphicsWindow(0,0,100,100), scene);

		QVBoxLayout* layout = new QVBoxLayout;
		layout->addWidget(renderWidget);
		layout->setContentsMargins(0, 0, 0, 1);
		setLayout( layout );

		connect( &_timer, SIGNAL(timeout()), this, SLOT(update()) );
		_timer.start( 10 );
	}

	QWidget* getRenderWidget( osgQt::GraphicsWindowQt* gw, osg::Node* scene )
	{
		osg::Camera* camera = this->getCamera();
		camera->setGraphicsContext( gw );

		const osg::GraphicsContext::Traits* traits = gw->getTraits();

		camera->setClearColor( osg::Vec4(0.0, 0.0, 0.0, 1.0) );
		camera->setViewport( new osg::Viewport(0, 0, traits->width, traits->height) );
		camera->setProjectionMatrixAsPerspective(45.0f, static_cast<double>(traits->width)/static_cast<double>(traits->height), 0.1f, 100.0f );
		camera->setViewMatrixAsLookAt(osg::Vec3d(75, 75, 75), osg::Vec3d(0, 0, 0), osg::Vec3d(0, 1, 0));

		this->setSceneData( scene );

		return gw->getGLWidget();
	}

	osgQt::GraphicsWindowQt* createGraphicsWindow( int x, int y, int w, int h, const std::string& name="", bool windowDecoration=false )
	{
		osg::DisplaySettings* ds = osg::DisplaySettings::instance().get();
		osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
		traits->windowName = name;
		traits->windowDecoration = windowDecoration;
		traits->x = x;
		traits->y = y;
		traits->width = w;
		traits->height = h;
		traits->doubleBuffer = true;
		traits->alpha = ds->getMinimumNumAlphaBits();
		traits->stencil = ds->getMinimumNumStencilBits();
		traits->sampleBuffers = ds->getMultiSamples();
		traits->samples = ds->getNumMultiSamples();

		return new osgQt::GraphicsWindowQt(traits.get());
	}

	virtual void paintEvent( QPaintEvent* event )
	{ 
		frame(); 
	}

protected:

	QTimer _timer;
};


osg::Node*	buildScene()
{
	Model *pModel = new MilkshapeModel();					
	pModel->loadModelData( "Data/model.ms3d");
	pModel->reloadTextures();

	osg::Group *root = new osg::Group;
	osg::MatrixTransform *rotYMT = new osg::MatrixTransform;
	rotYMT->addUpdateCallback(new osg::AnimationPathCallback(osg::Vec3(), osg::Y_AXIS, 2.5));
	rotYMT->addChild(pModel->drawGeode());
	root->addChild(rotYMT);

	return root;
}


int main( int argc, char** argv )
{
	QApplication app(argc, argv);
	ViewerWidget* viewWidget = new ViewerWidget(buildScene());
	viewWidget->setGeometry( 100, 100, 640, 480 );
	viewWidget->show();
	return app.exec();
}