Thread: Class question

Hallo,

I am working with adding geometry to a program I am making, and have some questions about the uses of classes.

Here is my class(s) so far. The idea is to have on base class that has the information that is common for all the geometry types, and then have subclasses(?) for the things that are different.

Code:

class Primitive
{
      public:
             Primitive();
             ~Primitive();
             
             void setType(); // ??
             void getType(); // ??   
             
             void setName(std::string n);   
             std::string getName();
             
             void setMaterial(Material m);
             Material getMaterial();
             
             void setPos(Vector3D pos);
             Vector3D getPos();
             
      private:
              //type
              std::string name;
              Material material;
              Vector3D position;
};

class sphere : public Primitive
{
      public:
             void setRadius(float r);
             float getRadius();
             float getRadiusSqr();
             
             result intersectionTest(Ray r);
             
      private:
              float radius;
              float radiusSqr;
};

Is this a good way of doing it?

Also, for the setType/getType, how would you do them? I want to be able to do something like:
setType(SPHERE);
and than it knows that that primitive is a sphere. Should I define SPHERE as 1, BOX as 2 and so on, and do it that way?

Hey,

I am still working on this, how can I acces the intersectionTest() from a primitive?

Here is how I try to do it:

Code:

                // Find the primitive we are currently testing against
                 Primitive testObject = thisScene.getPrimitive(currentPrimitive);
                 
                 // Check if the ray hits the current object
                 intersectionRes = testObject.intersectionTest(currentRay);

But it tells me that intersectionTest is not a member of primitive

thisScene is basicly an array of primitives.
getPrimitive returns a given primitive.

Code:

class Primitive
{
      public:
             Primitive(std::string n = "DefaultName");
             ~Primitive();
             
             void setType(); // ??
             void getType(); // ??   
             
             void setName(std::string n);   
             std::string getName();
             
             void setMaterial(Material m);
             Material getMaterial();
             
             void setPos(Vector3D pos);
             Vector3D getPos();
             
      private:
              //type
              std::string name;
              Material material;
              Vector3D position;
};

// The subclass for a sphere
class Sphere : public Primitive
{
      public:
             void setRadius(float r);
             float getRadius();
             float getRadiusSqr();
             
             result intersectionTest(Ray r);
             
             
      private:
              float radius;
};

What is currentPrimitive then? You are not giving enough information.

Sorry, here is how it is done:
First I have a class that holds all the information about the primitives I have

Code:

// This is the class that holds the scene we are rendering. It has all the 
// object created stored inside 
class Scene
{
      public:
             Scene(){};
             ~Scene();
             
             void createScene();
             
             int getNrPrimitives();
             Primitive getPrimitive(int i);
             
             int getNrLights();
             //Light getLight(int i);
             
      private:
              int nrPrimitives;                // nr of primitives in the scene
              Primitive** primitiveList;  // A list of all the primitives in the scene
              
              int nrLights;
              //Light** lightList;
};

and primitive is decleared as above.

Then I have a loop that loops trough all othe object to find the closest one

Code:

            // Loop through all the primitives in the scene and return the 
            // the closest one
// totalPrimitves = the total amount of objects in the scene
            for (int currentPrimitive = 0; currentPrimitive <=totalPrimitves;
                 currentPrimitive++)
            {
                 // Find the primitive we are currently testing against
                 Primitive testObject = thisScene.getPrimitive(currentPrimitive);
                 
                 // Check if the ray hits the current object
                 intersectionRes = testObject.intersectionTest(currentRay);
             }

Furthermore, you have not taken any of the advice given in this thread

I know, as I do not fully understand what you tell me to do. I am trying to ask for more information, aswell as reading online.

I tryed to do the changes you wrote but I get this erro:
invalid return type for member function `Primitive Scene::getPrimitive(int)'
because the following virtual functions are abstract:

Thanks for all your help so far

Thanks for the links. Accually the whole page was kind of nice[bookmarked].

I am still working on this, but I think I have made some progress at least.
Now I dont get any erros when compiling the class, but I do when I try to acces members of the sphere class.

Here is what I have for my classes

Code:

class Primitive
{
      public:
             Primitive(std::string n = "DefaultName");
             //~Primitive();
             
             //void setType(); // ??
             //void getType(); // ??   
             
             void setName(std::string n);   
             virtual std::string getName();
             
             void setMaterial(Material m);
             virtual Material* getMaterial();
             
             void setPos(Vector3D pos);
             virtual Vector3D getPos();
             
             virtual result intersectionTest(Ray r) = 0;
             
      private:
              //type
              std::string name;
              Material material;
              Vector3D position;
};

// The subclass for a sphere
class Sphere : public Primitive
{
      public:
             void setRadius(float r);
             float getRadius();
             float getRadiusSqr();
             
             result intersectionTest(Ray r); 
      private:
              float radius;
};

And here I try to use it:

Code:

// Create a container for all the objects in the scene
     primitiveList = new Primitive*[100];
     
     // Add some object to the scene
     // ----------------------------------------
     
        // A small blue sphere at the scene of the screen
        primitiveList[0] = new Sphere;
        primitiveList[0]->setName("SmallBlueSphere");
        primitiveList[0]->setPos(Vector3D(0,-50,0));
        primitiveList[0]->setRadius(20);
        primitiveList[0]->setMaterial(Material(0,0,255,0)); // Blue with 0 diffuse
        
        primitiveList[1] = new Sphere;
        primitiveList[1]->setName("BigRedSphere");
        primitiveList[1]->setPos(Vector3D(0,50,0));
        primitiveList[1]->setRadius(50);
        primitiveList[1]->setMaterial(Material(255,0,0,0));
     
     // -----------------------------------------
     // Done with the scene

The error I get is:
'class Primitive' has no member named 'setRadius'

Not sure why this happens. I can acces all the functions in the Primitive class, but not in the SPhere class. This would have made sense to me if I had done new Primitive insted of new Sphere.

So, again I need a helping hand...

Thanks for you time