Drawing 3D Objects - Flash 3D: Animation, Interactivity, and Games - page 316

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// ------------------------------------------------------
// convert 3D coordinates to screen coordinates

getScreenCoords = function()
{
// update the camera distance position
d += camdz;

// update the object position
for ( var n:Number = 0; n < numPts; n++ )
{
x[n] += tx;
y[n] += ty;
z[n] += tz;
}

// update the object size
for ( var n:Number = 0; n < numPts; n++ )
{
x[n] = sx *(x[n]-xc) + xc;
y[n] = sy *(y[n]-yc) + yc;
z[n] = sz *(z[n]-zc) + zc;
}

// add changes due to rotating the shape
rotateObject(rx,ry,rz);

// convert to screen coordinates
for ( var n:Number = 0; n < numPts; n++ )
{
xs[n] = x[n]*d/(d + z[n])
ys[n] = -y[n]*d/(d + z[n])
}
}

picture plane is updated (line 73). Next, the 3D coordinates of the object are updated
as the result of any translation (lines 78-80).

The size of the object is adjusted based on the current vales of the scale factors sx ,
sy , and sz (lines 86-88). Any scale factors greater than 1 will stretch the object in that
dimension, while any scale factor less than 1 will shrink the object in that dimension.