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/*
* 3D Bressenham DDA
*
* Adrian Bowyer
* 10 October 2001
*
*/
//#define uc unsigned char // Saves typing...
//#define CR '\r' // Carriage return
// Swap a pair of integers
inline void swp(int& a, int& b)
{
int t;
t = a;
a = b;
b = t;
}
// 3-dimensional Bressenham DDA
class dda
{
private:
// x, y, z are the current point
// xo, yo, zo are the start point
// xd, yd, zd are the differences between the start and end
// iy, iz are the y and z DDA sums
// nx, ny, nz are flags for the x, y, and z differences being negative
// sxy and sxz are flags to swap x and y, and to swap x and z
int x, y, z, xo, yo, zo, xd, yd, zd, iy, iz, nx, ny, nz, sxy, sxz;
public:
// Constructor initializes everything given where we are and where
// we want to go.
dda(int x0, int y0, int z0, int x1, int y1, int z1)
{
xo = x0;
yo = y0;
zo = z0;
xd = x1 - x0;
yd = y1 - y0;
zd = z1 - z0;
if(nx = (xd < 0)) xd = -xd;
if(ny = (yd < 0)) yd = -yd;
if(nz = (zd < 0)) zd = -zd;
if(sxy = (xd < yd)) swp(xd, yd);
if(sxz = (xd < zd)) swp(xd, zd);
x = 0;
y = 0;
z = 0;
iy = -xd/2;
iz = iy;
}
// Return the current point, given all the negates and swaps
void point(int& a, int& b, int& c)
{
a = x;
b = y;
c = z;
if(sxz) swp(a, c);
if(sxy) swp(a, b);
if(nx) a = -a;
if(ny) b = -b;
if(nz) c = -c;
a = a + xo;
b = b + yo;
c = c + zo;
}
// Take 1 step of the DDA.
// Return 1 if we're still going, 0 if we've finished
int step()
{
x++;
iy = iy + yd;
if(iy > 0)
{
iy = iy - xd;
y++;
}
iz = iz + zd;
if(iz > 0)
{
iz = iz - xd;
z++;
}
return(x <= xd);
}
};
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