memory allocation problem (well... I guess so)

[berthelot samuel]

Hi,
I have a problem with structures that lose their content when I pass
them to a function.

Here are the structures

typedef struct VERTEX
{
int id; /* id of this vertex */
float x, y, z; /* vertex coordinates */
float u, v; /* texture coordinates */
float r, g, b; /* rgb colour of the vertex */
float normal[3]; /* x y z values of the normal */
}vertex;

typedef struct FACE
{
int vertices[3];/* list of vertices corresponding to this face */
CVector normal; /* x y z values of the normal */
}face;

typedef struct OBJECT3D
{
vertex *vertices; /* hold the vertices of the object3D */
face *faces; /* hold the faces of the object3D */
int vcnt; /* number of vertices of the object3D */
int fcnt; /* number of faces of the object3D */
CVector center; /* center of the object - used for bounding box
*/
float width; /* max width of the object -used for bounding box */
void ComputeBB(); /* compute the bounding box of the object */
}object3D;
typedef struct WORLD3D
{
int numObjects; /* number of objects in the world */
vector<object3D > m_objList; /* list of objects in the world */
}world3D;

And there I create my objects and I add them to a vector
object3D myObject;
memset(&myObjec t, 0, sizeof(object3D ));
g_world.numObje cts ++;

myObject.vcnt = 8;
myObject.vertic es = new vertex[myObject.vcnt];
myObject.vertic es = vertices;

myObject.fcnt = 10;
myObject.faces = new face[myObject.fcnt];
myObject.faces = faces;

g_world.m_objLi st.push_back(my Object);

I've checked with the debugger and g_world contains everything ok. The
problem is there:
m_octree->BuildRootNode( &g_world, m_city->GetNumPoly() ,
m_octree->GetCenter(), m_octree->GetSize());

In BuildRootNode(. ..) g_world doesn't contain the value of vertices
and faces any more. I believe it's related to the way I pass it to the
function, but I'm not too sure about that.
Thanx for any help.
Sam

[John Harrison]

"berthelot samuel" <sa************ **@voila.fr> wrote in message
news:ca******** *************** ***@posting.goo gle.com...

Hi,
I have a problem with structures that lose their content when I pass
them to a function.

Here are the structures

typedef struct VERTEX
{
int id; /* id of this vertex */
float x, y, z; /* vertex coordinates */
float u, v; /* texture coordinates */
float r, g, b; /* rgb colour of the vertex */
float normal[3]; /* x y z values of the normal */
}vertex;

typedef struct FACE
{
int vertices[3];/* list of vertices corresponding to this face */
CVector normal; /* x y z values of the normal */
}face;

typedef struct OBJECT3D
{
vertex *vertices; /* hold the vertices of the object3D */
face *faces; /* hold the faces of the object3D */
int vcnt; /* number of vertices of the object3D */
int fcnt; /* number of faces of the object3D */
CVector center; /* center of the object - used for bounding box
*/
float width; /* max width of the object -used for bounding box */
void ComputeBB(); /* compute the bounding box of the object */
}object3D;
typedef struct WORLD3D
{
int numObjects; /* number of objects in the world */
vector<object3D > m_objList; /* list of objects in the world */
}world3D;

And there I create my objects and I add them to a vector
object3D myObject;
memset(&myObjec t, 0, sizeof(object3D ));
g_world.numObje cts ++;

myObject.vcnt = 8;
myObject.vertic es = new vertex[myObject.vcnt];
myObject.vertic es = vertices;
What is this? Why do you assign to vertices twice? What is the veritices
variable?

I think you probably meant something like this

myObject.vertic es = new vertex[myObject.vcnt];
for (int i = 0; i < myObject.vcnt; ++i)
myObject.vertic es[i] = vertices[i];

myObject.fcnt = 10;
myObject.faces = new face[myObject.fcnt];
myObject.faces = faces;
Some problem again.

g_world.m_objLi st.push_back(my Object);

You've already used vectors elsewhere in your code, so why didn't you use
them for vertices and faces? As you've seen using pointers and dynamic
memory is tricky. Consider doing this instead

struct OBJECT3D
{
vector<vertex> vertices; /* hold the vertices of the object3D */
vector<face> faces; /* hold the faces of the object3D */
CVector center; /* center of the object - used for bounding box */
float width; /* max width of the object -used for bounding box */
void ComputeBB(); /* compute the bounding box of the object */
};

john

[Rob Williscroft]

berthelot samuel wrote in news:ca34f197.0 406170438.14bf7 976
@posting.google .com in comp.lang.c++:

myObject.vertic es = new vertex[myObject.vcnt];
myObject.vertic es = vertices; myObject.faces = new face[myObject.fcnt];
myObject.faces = faces; In BuildRootNode(. ..) g_world doesn't contain the value of vertices
and faces any more. I believe it's related to the way I pass it to the
function, but I'm not too sure about that.
Thanx for any help.

If thats not enough then you haven't posted enough relevent code.

HTH.

Rob.
--
http://www.victim-prime.dsl.pipex.com/

[John Harrison]

Also don't use CVector, why use two different vector classes in the same
program, isn't that just confusing? Stick to vector, it is by far the best
alternative.

john

[Sharad Kala]

"berthelot samuel" <sa************ **@voila.fr> wrote in message
news:ca******** *************** ***@posting.goo gle.com...

Hi,
I have a problem with structures that lose their content when I pass
them to a function.

What are CVector, g_world etc??
Post the minimal compilable code that demonstrates your problem. Then someone
can help you here.

[Marcin Kalicinski]

U¿ytkownik "John Harrison" <jo************ *@hotmail.com> napisa³ w
wiadomo¶ci news:2j******** *****@uni-berlin.de...

Also don't use CVector, why use two different vector classes in the same
program, isn't that just confusing? Stick to vector, it is by far the best
alternative.

From the code, I think that OP CVector is a mathematical vector with 3 float
components, implementing some maths operations like dot product etc. So it
cannot be replaced with std::vector.

Anyway, I wonder why he hadn't used it for VERTEX position or normal.

Best regards,
Marcin