ogre获取Mesh的顶点数组和索引数组

注意：下面getMeshInformation函数的代码应该来自网上的某一位前辈的，找不到出处了，望不要怪我

后面还有个函数做射线和网格的三角形相交测试，可以知道是否相交，也可以得到交点。

void getMeshInformation(const Ogre::MeshPtr& mesh,

size_t &vertex_count,

Ogre::Vector3* &vertices,

size_t &index_count,

unsigned long* &indices)

{

bool added_shared = false;

size_t current_offset = 0;

size_t shared_offset = 0;

size_t next_offset = 0;

size_t index_offset = 0;

vertex_count = index_count = 0;

// Calculate how many vertices and indices we're going to need

for ( unsigned short i = 0; i < mesh->getNumSubMeshes(); ++i)

{

Ogre::SubMesh* submesh = mesh->getSubMesh(i);

// We only need to add the shared vertices once

if(submesh->useSharedVertices)

{

if( !added_shared )

{

vertex_count += mesh->sharedVertexData->vertexCount;

added_shared = true;

}

}

else

{

vertex_count += submesh->vertexData->vertexCount;

}

// Add the indices

index_count += submesh->indexData->indexCount;

}

// Allocate space for the vertices and indices

vertices = new Ogre::Vector3[vertex_count];

indices = new unsigned long[index_count];

added_shared = false;

// Run through the submeshes again, adding the data into the arrays

for (unsigned short i = 0; i < mesh->getNumSubMeshes(); ++i)

{

Ogre::SubMesh* submesh = mesh->getSubMesh(i);

Ogre::VertexData* vertex_data = submesh->useSharedVertices ? mesh->sharedVertexData : submesh->vertexData;

if ((!submesh->useSharedVertices) || (submesh->useSharedVertices && !added_shared))

{

if(submesh->useSharedVertices)

{

added_shared = true;

shared_offset = current_offset;

}

const Ogre::VertexElement* posElem =

vertex_data->vertexDeclaration->findElementBySemantic(Ogre::VES_POSITION);

Ogre::HardwareVertexBufferSharedPtr vbuf =

vertex_data->vertexBufferBinding->getBuffer(posElem->getSource());

unsigned char* vertex =

static_cast<unsigned char*>(vbuf->lock(Ogre::HardwareBuffer::HBL_READ_ONLY));

// There is _no_ baseVertexPointerToElement() which takes an Ogre::Real or a double

// as second argument. So make it float, to avoid trouble when Ogre::Real will

// be comiled/typedefed as double:

//Ogre::Real* pReal;

float* pReal;

for( size_t j = 0; j < vertex_data->vertexCount; ++j, vertex += vbuf->getVertexSize())

{

posElem->baseVertexPointerToElement(vertex, &pReal);

Ogre::Vector3 pt(pReal[0], pReal[1], pReal[2]);

vertices[current_offset + j] = pt ;

}

vbuf->unlock();

next_offset += vertex_data->vertexCount;

}

Ogre::IndexData* index_data = submesh->indexData;

size_t numTris = index_data->indexCount / 3;

Ogre::HardwareIndexBufferSharedPtr ibuf = index_data->indexBuffer;

bool use32bitindexes = (ibuf->getType() == Ogre::HardwareIndexBuffer::IT_32BIT);

unsigned long* pLong = static_cast<unsigned long*>(ibuf->lock(Ogre::HardwareBuffer::HBL_READ_ONLY));

unsigned short* pShort = reinterpret_cast<unsigned short*>(pLong);

size_t offset = (submesh->useSharedVertices)? shared_offset : current_offset;

if ( use32bitindexes )

{

for ( size_t k = 0; k < numTris*3; ++k)

{

indices[index_offset++] = pLong[k] + static_cast<unsigned long>(offset);

}

}

else

{

for ( size_t k = 0; k < numTris*3; ++k)

{

indices[index_offset++] = static_cast<unsigned long>(pShort[k]) +

static_cast<unsigned long>(offset);

}

}

ibuf->unlock();

current_offset = next_offset;

}

}

射线与网格的三角形进行相交测试

int CObj::rayIntersection(Ogre::Ray ray)

{

int num=0;

for(unsigned int i=0; i<index_count; i+=3)

{

//vertices that make up the triangle

Ogre::Vector3 A = m_transVertices[m_indices[i]];

Ogre::Vector3 B = m_transVertices[m_indices[i+1]];

Ogre::Vector3 C = m_transVertices[m_indices[i+2]];

std::pair<bool, float> tmp = Ogre::Math::intersects(ray, A,B,C, true, true);

if(tmp.first)

{

num++;

return true;

}

}

return num;

}