C++ Data Structure for storing 3 dimensions of floats.

Question

I've implemented a 3D strange attractor explorer which gives float XYZ outputs in the range 0-100, I now want to implement a colouring function for it based upon the displacement between two successive outputs.

I'm not sure of the data structure to use to store the colour values for each point, using a 3D array I'm limited to rounding to the nearest int which gives a very coarse colour scheme.

I'm vaguely aware of octtrees, are they suitable in this siutation?

EDIT: A little more explanation:

to generate the points i'm repeatedly running this:

(a,b,c,d are random floats in the range -3 to 3)

x = x2;
y = y2;
z = z2;

x2 = sin(a * y) - z * cos(b * x);
y2 = z2 * sin(c * x) - cos(d * y);
z2 = sin(x);

parr[i][0]=x;
parr[i][1]=y;
parr[i][2]=z;

which generates new positions for each axis each run, to colour the render I need to take the distance between two successive results, if I just do this with a distance calculation between each run then the colours fade back and forth in equilibrium so I need to take running average for each point and store it, using a 3dimenrsionl array is too coarse a colouring and I'm looking for advice on how to store the values at much smaller increments.

Answer 1

I'd probably think bout some kind of 3-d binary search tree.

template <class KEY, class VALUE>
class BinaryTree
{
    // some implementation, probably available in libraries
public:
    VALUE* Find(const KEY& key) const
    {
        // real implementation is needed here
     return NULL; 
    }

};

// this tree nodes wil actually hold color
class BinaryTree1 : public BinaryTree<double, int>
{
};

class BinaryTree2 : public BinaryTree<double, BinaryTree1>
{
};

class BinaryTree3 : public BinaryTree<double, BinaryTree2>
{
};

And you function to retreive the color from this tree would look like that

bool    GetColor(const BinaryTree3& tree, double dX, double dY, double& dZ, int& color)
{
    BinaryTree2* pYTree = tree.Find(dX);
    if( NULL == pYTree )
     return false;

    BinaryTree1* pZTree = pYTree->Find(dY);
    if( NULL == pZTree )
     return false;

    int* pCol = pZTree->Find(dZ);
    if( NULL == pCol )
     return false;

    color = *pCol;
    return true;
}

Af course you will need to write the function that would add color to this tree, provided 3 coordinates X, Y and Z. std::map appears to be a good candidate for base class.

Answer 2

Maybe you could drop the 2-dim array off and use an 1-dim array of

struct ColoredPoint {

   int   x;
   int   y;
   int   z;

   float color;
};

so that the code would look like

 ...
 parr[i].x     = x;
 parr[i].y     = y;
 parr[i].z     = z;
 parr[i].color = some_computed_color;

(you may also wish to encapsulate the fields and use class ColoredPoint with access methods)