Look at file tut04.rt . There is a new param section.
Param section allows to change the parameters which determinate the way to build the image. Below are described the principal attribute of param section:
dimx, dimy
represent the image dimension in pixel ( default is 100x100 ).
If you change the image dimension, and horizontal dimension becames different from vertical, you can affect the aspect ratio, so circles became ellipses and squares rectangles. To avoid this you must change the view window in the view section ( look at paragraph "Understanding the view" ), or , simply, always use squared image of any dimension, with dimx = dimy.
shade
is the way the color will be computed. The allowed values are "phong"
and "noshadowsphong". The default is "phong". "phong" and "noshadowphong"
are similar, but "noshadowphong" does not compute the shadows. It is faster,
but the image could be lighter.
mode
is the number of deviation allowed for a ray. If you set =0 you will
not see transparency and reflection. Don' t specificate big value. A value
of 5 or 7 is good for transparence.
anti_alias
is a technique for creating a smoothed image. Set to 1 if you want,
o if not. The program will use adaptive antialiasing.
backcolor
is the color of the background. its value is in rgb format.
buildhier if set to 1, create an automatic hierarchy to speedup
the creation of the image. If set to 0 no hierarchy is used. This will
be explained later.