Create a Set of Lines with Tetrahetra Centered at Points along the Lines
Description
Creates a scene consisting of lines made up of small tetrahedra centered at points along them.
Usage
1 2 3 4 
Arguments
x, y, z 
numeric vectors of length two or matrices with two columns representing coordinates of starting and ending points of line(s). 
delta 
numeric; increase in each dimension used to locate points along the lines; recycled to length 3. 
lwd 
numeric; used for the size of the tetrahedron in each dimension; recycled to length 3. 
color 
color to use for the tetrahedra. 
... 
additional arguments to be passed on to

Details
The function uses the Bresenham's line algorithm to locate points along lines and then creates a triangle mesh scene representing tetrahedra centered at those points.
Value
Returns a triangle mesh scene representing the lines.
See Also
lines3d
.
Examples
1 2 3 4 5 6 7 8 9 10 11 12  p < pointsTetrahedra(x=c(100,100, 257, 257),
y=c(100,100, 257, 257),
z=c(100,257, 257, 100), size=1)
l < linesTetrahedra(x=matrix(c(100,257,
100,257), nrow=2, byrow=TRUE),
y=matrix(c(100,257,
100,257), nrow=2, byrow=TRUE),
z=matrix(c(100,257,
257,100), nrow=2, byrow=TRUE),
lwd=0.4,
col="red")
drawScene.rgl(list(p, l))
