Confusing segmentation fault - c++

Question

EDIT: I basically revamped the whole question so I could provide an executable example...
I have been getting a segmentation fault that I can't figure out. Here is a compacted version of my code. I maintained the original class hierarchy even though some of the classes have no relevant methods since I think that it has something to do with my issue, especially after some of the comments I've been getting.
#import <vector>
using namespace std;
template<class Data = float>
class Vector
{
// All pure virtual functions.
};
template<class Data>
class TranslationVector : public virtual Vector<Data>
{
// All pure virtual functions.
};
template<class Data>
class SimpleVector4 : public virtual Vector<Data>
{
public:
SimpleVector4(const Data d0, const Data d1, const Data d2, const Data d3)
{
fData = new vector<Data> ;
fData->push_back(d0);
fData->push_back(d1);
fData->push_back(d2);
fData->push_back(d3);
}
vector<Data>*
getData()
{
return (fData);
}
private:
vector<Data>* fData;
};
template<class Data>
class SimpleTranslationVector4 : public SimpleVector4<Data> , public TranslationVector<Data>
{
public:
SimpleTranslationVector4(const Data x, const Data y, const Data z, const Data w) :
SimpleVector4<Data> (x, y, z, w)
{
}
};
template<class Data = float>
class Matrix
{
// All pure virtual functions.
};
template<class Data>
class TransformationMatrix : public virtual Matrix<Data>
{
// All pure virtual functions.
virtual void
translate(TranslationVector<Data>* const translation) = 0;
};
template<class Data>
class SimpleMatrix44 : public virtual Matrix<Data>
{
public:
SimpleMatrix44()
{
fData = new vector<Data> (CELLS_IN_MATRIX, 0);
setIdentity();
}
vector<Data>*
getData()
{
return (fData);
}
void
setIdentity()
{
fData->at(0) = 1;
fData->at(1) = 0;
fData->at(2) = 0;
fData->at(3) = 0;
fData->at(4) = 0;
fData->at(5) = 1;
fData->at(6) = 0;
fData->at(7) = 0;
fData->at(8) = 0;
fData->at(9) = 0;
fData->at(10) = 1;
fData->at(11) = 0;
fData->at(12) = 0;
fData->at(13) = 0;
fData->at(14) = 0;
fData->at(15) = 1;
}
private:
static const int CELLS_IN_MATRIX = 16;
vector<Data>* fData;
};
template<class Data>
class SimpleTransformationMatrix44 : public SimpleMatrix44<Data> , public TransformationMatrix<Data>
{
public:
SimpleTransformationMatrix44() :
SimpleMatrix44<Data> ()
{
}
void
translate(TranslationVector<Data>* translation)
{
vector<Data> *data = SimpleMatrix44<Data>::getData();
vector<Data> *transData = ((SimpleVector4<Data>*) translation)->getData();
// The error occurs on this line:
data->at(12) += data->at(0) * transData->at(0) + data->at(4) * transData->at(1) + data->at(8) * transData->at(2);
data->at(13) += data->at(1) * transData->at(0) + data->at(5) * transData->at(1) + data->at(9) * transData->at(2);
data->at(14) += data->at(2) * transData->at(0) + data->at(6) * transData->at(1) + data->at(10) * transData->at(2);
data->at(15) += data->at(3) * transData->at(0) + data->at(7) * transData->at(1) + data->at(11) * transData->at(2);
}
};
int
main(int argc, char** argv)
{
SimpleTransformationMatrix44<float> matrix1;
matrix1.translate(new SimpleTranslationVector4<float> (0.0f, 10.0f, 0.0f, 1.0f));
return 0;
}
I have commented in the code where the error occurs. From debugging I can see that it actually occurs in the size() function of vector and that transData has not been initialized. I can't for the life of me figure out why transData has not been initialized! Any ideas?
Thanks,
Gaz.

Answer 1

Cast of non-inherited classes seems to be your error.
Let's see your code. There is a conversion of SimpleTranslationVector4<float>* to TranslationVector<float>* while invoking the translate function. Then the converted value is converted again into SimpleVector4<float>*. But the SimpleVector4<float> does not inherit TranslationVector<float>.
This code also results in error.
template<class Data>
class SimpleVector4 {
public:
int a;
};
template<class Data>
class TranslationVector {
};
template<class Data>
class SimpleTranslationVector4 : public SimpleVector4<Data>,
public TranslationVector<Data> {
};
int main() {
SimpleTranslationVector4<float> A;
SimpleVector4<float>* b = (SimpleVector4<float>*)&A;
TranslationVector<float>* c = (TranslationVector<float>*)&A;
SimpleVector4<float>* d = (SimpleVector4<float>*)c;
b->a = 1; // ok
d->a = 1; // error
}

Answer 2

You're doing a C-style cast between unrelated types. This is not safe. The fact that you need to do this at all probably indicates a problem in your design, but try replacing this:
vector<Data>* transData = ((SimpleVector4<Data>*) translation)->SimpleVector4<Data>::getData();
with this:
vector<Data>* transData = dynamic_cast<SimpleVector4<Data>*>(translation)->getData();