检索 OGRE 3D 1.81 子网格数据时出现分段错误。我尝试使用http://alumni.cs.ucr.edu/~sorianom/cs134_09win/中的代码 来获取供子弹物理引擎使用的食人魔网格数据，但遇到了一条错误消息，指出段错误。减少代码找到原因后我发现它是“ submesh->indexData->indexStart“导致段错误。我在Ubuntu Linux 12.10（32bit x86）上运行（由于预算限制，我们买不起Windows），并使用g ++作为编译器。请帮助我，我是一名小学教师尝试为学生制作一些 CAI 程序来学习数学、英语……我知道网站上列出的 cs134 示例代码有点太旧了，我已经升级了所有的网格，dotsceneloader……但仍然无法弄清楚是什么必须更改。谢谢！以下是仍然使段错误错误消息的简化代码。
#include <Ogre.h>
#include <ExampleApplication.h>
#include <btBulletCollisionCommon.h>
class SampleApp : public ExampleApplication
{
public:
// Basic constructor
SampleApp()
{}
protected:
// Just override the mandatory create scene method
void createScene(void) {
mSceneMgr->setSkyBox(true, "Examples/CloudyNoonSkyBox");
Ogre::Light* myLight = mSceneMgr->createLight("Light0");
myLight->setType(Light::LT_POINT);
myLight->setPosition(0, 40, 0);
myLight->setDiffuseColour(1, 1, 1);
myLight->setSpecularColour(1, 1, 1);
Ogre::Entity* entity = mSceneMgr->createEntity("ogre", "ogrehead.mesh");
mSceneMgr->getRootSceneNode()->createChildSceneNode()->attachObject(entity);
Ogre::MeshPtr mesh = entity->getMesh();
Ogre::Mesh::SubMeshIterator j = mesh->getSubMeshIterator();
while (j.hasMoreElements()) {
Ogre::SubMesh* submesh = j.getNext();
std::cout << " submesh:" << submesh << "\n";
std::cout << " submesh->indexData:" << submesh->indexData << "\n";
//std::cout << " submesh->indexData->indexStart:" << submesh->indexData->indexStart << "\n";
int idxStart = submesh->indexData->indexStart;
int nIdx = submesh->indexData->indexCount;
}
}
};
// ----------------------------------------------------------------------------
// Main function, just boots the application object
// ----------------------------------------------------------------------------
#if OGRE_PLATFORM == OGRE_PLATFORM_WIN32
#define WIN32_LEAN_AND_MEAN
#include "windows.h"
INT WINAPI WinMain( HINSTANCE hInst, HINSTANCE, LPSTR strCmdLine, INT )
#else
int main(int argc, char **argv)
#endif
{
// Create application object
SampleApp app;
try
{
app.go();
}
catch( Exception& e )
{
#if OGRE_PLATFORM == OGRE_PLATFORM_WIN32
MessageBox( NULL, e.getFullDescription().c_str(), "An exception has occured!", MB_OK | MB_ICONERROR | MB_TASKMODAL);
#else
std::cerr << "An exception has occured: " << e.getFullDescription();
#endif
}
return 0;
}
和错误信息：
....
submesh:0xb752c080
submesh->indexData:0x8d042444
Segmentation fault (core dumped)
------------------
(program exited with code: 139)
以下是 gdb 输出：
(gdb) print submesh->indexData
$5 = (Ogre::IndexData *) 0x8d042444
(gdb) print submesh->indexData->indexStart
Cannot access memory at address 0x8d042458
(gdb)
ps：编译器设置：（上面的代码是由 CODE:BLOCK OGRE3D 模板修改的，可以编译，这个精简版不需要项目符号部分）
g++ -o "%e" "%f" pkg-config --cflags --libs OGRE OIS bullet -I/usr/local/include/OGRE -I/usr/include/bullet
原始文件如下（来自http://tutorialsdl.googlecode.com/svn/trunk/Lab3/Lab3/OgreToBtMeshConverter.cpp）：
#include <Ogre.h>
#include <ExampleApplication.h>
#include <btBulletCollisionCommon.h>
class SampleApp : public ExampleApplication
{
public:
// Basic constructor
SampleApp()
{}
protected:
// Just override the mandatory create scene method
void createScene(void) {
mSceneMgr->setSkyBox(true, "Examples/CloudyNoonSkyBox");
Ogre::Light* myLight = mSceneMgr->createLight("Light0");
myLight->setType(Light::LT_POINT);
myLight->setPosition(0, 40, 0);
myLight->setDiffuseColour(1, 1, 1);
myLight->setSpecularColour(1, 1, 1);
Ogre::Entity* entity = mSceneMgr->createEntity("ogre", "ninja.mesh");
mSceneMgr->getRootSceneNode()->createChildSceneNode()->attachObject(entity);
//
// initialize bullets collision detection system
//
btVector3 worldAabbMin(-1000,-1000,-1000);
btVector3 worldAabbMax(1000,1000,1000);
btDefaultCollisionConfiguration* mColConfig;
btCollisionWorld* mColWorld;
btCollisionDispatcher* mDispatcher;
btAxisSweep3* mBroadphase;
mBroadphase = new btAxisSweep3(worldAabbMin, worldAabbMax); // broadphase
mColConfig = new btDefaultCollisionConfiguration();
mDispatcher = new btCollisionDispatcher(mColConfig); // narrowphase pair-wise checking
mColWorld = new btCollisionWorld(mDispatcher, mBroadphase, mColConfig);
//
// Registers every mesh in OGREs scene manager with the
// collision world. You should be adding your environment
// to the scene manager before this call. Your moveable
// character should be created after this call as to avoid
// having his mesh become part of the static level geometry.
//
// All meshes here are placed into group 2 and set to
// collide with group 1. You character should be in group
// 1, and set to collide with group 2. More about contact groups
// in the manual.
btCollisionWorld* colWorld=0;
registerEntityAsCollider(entity,colWorld);
}
void registerEntityAsCollider(Entity* entity, btCollisionWorld* colWorld)
{
// if you wish to do instancing you will have to share one
// btTriangleMesh amongst multiple btBvhTriangleMeshShape
// instances
btTriangleMesh* btMesh = new btTriangleMesh();
MeshPtr mesh = entity->getMesh();
Mesh::SubMeshIterator j = mesh->getSubMeshIterator();
while (j.hasMoreElements()) {
SubMesh* submesh = j.getNext();
int idxStart = submesh->indexData->indexStart;
int nIdx = submesh->indexData->indexCount;
HardwareIndexBuffer* idxBuffer
= submesh->indexData->indexBuffer.get();
HardwareVertexBufferSharedPtr virtBuffer;
VertexDeclaration* virtDecl;
if (submesh->useSharedVertices) {
virtDecl = mesh->sharedVertexData->vertexDeclaration;
assert(mesh->sharedVertexData->vertexBufferBinding->getBufferCount() > 0);
virtBuffer = mesh->sharedVertexData->vertexBufferBinding->getBuffer(0);
} else {
virtDecl = submesh->vertexData->vertexDeclaration;
assert(submesh->vertexData->vertexBufferBinding->getBufferCount() > 0);
virtBuffer = submesh->vertexData->vertexBufferBinding->getBuffer(0);
}
unsigned char* pVert = static_cast<unsigned char*>(virtBuffer->lock(HardwareBuffer::HBL_READ_ONLY));
// need to lock the buffer since vertex data resides on GPU
// and we need synchronization
unsigned short* sindices = NULL;
unsigned long* lindices = NULL;
if (idxBuffer->getType() == HardwareIndexBuffer::IT_16BIT) {
sindices = static_cast<unsigned short*>(idxBuffer->lock(HardwareBuffer::HBL_READ_ONLY));
} else if (idxBuffer->getType() == HardwareIndexBuffer::IT_32BIT) {
lindices = static_cast<unsigned long*>(idxBuffer->lock(HardwareBuffer::HBL_READ_ONLY));
} else {
assert(true == false);
}
const VertexElement* elm = virtDecl->findElementBySemantic(VES_POSITION, 0);
int offset = elm->getOffset();
assert(elm->getType() == VET_FLOAT3);
for (int k = idxStart; k < idxStart + nIdx; k += 3) {
unsigned int indices[3];
btVector3 vertices[3];
if (idxBuffer->getType() == HardwareIndexBuffer::IT_16BIT) {
for (int l = 0; l < 3; ++l) {
indices[l] = sindices[k + l];
}
} else {
for (int l = 0; l < 3; ++l) {
indices[l] = lindices[k + l];
}
}
for (int l = 0; l < 3; ++l) { // for each vertex
Real* posVert = (Real*)(pVert + indices[l] * virtBuffer->getVertexSize() + offset);
for (int m = 0; m < 3; ++m) { // for each vertex component
vertices[l][m] = posVert[m];
}
}
btMesh->addTriangle(vertices[0], vertices[1], vertices[2]);
}
idxBuffer->unlock();
virtBuffer->unlock();
}
btBvhTriangleMeshShape* btMeshShape = new btBvhTriangleMeshShape(btMesh, true, true);
btCollisionObject* btObj = new btCollisionObject();
btObj->setCollisionShape(btMeshShape);
Vector3 pos = entity->getParentSceneNode()->getPosition();
Quaternion orient = entity->getParentSceneNode()->getOrientation();
Vector3 scale = entity->getParentSceneNode()->getScale();
btMeshShape->setLocalScaling(btVector3(scale[0], scale[1], scale[2]));
btMeshShape->setMargin(0.0);
btTransform btTrans;
btTrans.setIdentity();
btTrans.setOrigin(btVector3(pos[0], pos[1], pos[2]));
btTrans.setRotation(btQuaternion(orient[1], orient[2], orient[3], orient[0]));
btObj->setWorldTransform(btTrans);
// the last 2 parameters are bit strings representing group membership
// and the groups which it is allowed to collide with
colWorld->addCollisionObject(btObj, 2, 1);
}
//
// This method will take every entity in your scene and register it as
// a mesh in the btCollisionWorld. NOTE: Be sure to call this function after
// you've added your static entities (environment) to the scene manager but
// before you add your characters.
//
void registerAllEntitiesAsColliders(SceneManager* sceneMgr, btCollisionWorld* colWorld)
{
SceneManager::MovableObjectIterator
i = sceneMgr->getMovableObjectIterator("Entity");
while (i.hasMoreElements()) {
Entity* entity = static_cast<Entity*>(i.getNext());
registerEntityAsCollider(entity, colWorld);
}
}
};
// ----------------------------------------------------------------------------
// Main function, just boots the application object
// ----------------------------------------------------------------------------
#if OGRE_PLATFORM == OGRE_PLATFORM_WIN32
#define WIN32_LEAN_AND_MEAN
#include "windows.h"
INT WINAPI WinMain( HINSTANCE hInst, HINSTANCE, LPSTR strCmdLine, INT )
#else
int main(int argc, char **argv)
#endif
{
// Create application object
SampleApp app;
try
{
app.go();
}
catch( Exception& e )
{
#if OGRE_PLATFORM == OGRE_PLATFORM_WIN32
MessageBox( NULL, e.getFullDescription().c_str(), "An exception has occured!", MB_OK | MB_ICONERROR | MB_TASKMODAL);
#else
std::cerr << "An exception has occured: " << e.getFullDescription();
#endif
}
return 0;
}