4.6 Light Source Parameters
This one deals with all the aspects of light source and Targa files.
You must choose the direction of the light from the light source. This
will be scaled in the x, y, and z directions the same as the image. For
example, 1,1,3 positions the light to come from the lower right front of
the screen in relation to the untransformed image. It is important to
remember that these coordinates are scaled the same as your image. Thus,
"1,1,1" positions the light to come from a direction of equal distances
to the right, below and in front of each pixel on the original image.
However, if the x,y,z scale is set to 90,90,30 the result will be from
equal distances to the right and below each pixel but from only 1/3 the
distance in front of the screen i.e.. it will be low in the sky, say,
afternoon or morning.
Then you are asked for a smoothing factor. Unless you used Continuous
Potential (p. 95) when generating the starting image, the illumination
when using light source fills may appear "sparkly", like a sandy beach
in bright sun. A smoothing factor of 2 or 3 will allow you to see the
large-scale shapes better.
Smoothing is primarily useful when doing light source fill types with
plasma clouds. If your fractal is not a plasma cloud and has features
with sharply defined boundaries (e.g. Mandelbrot Lake), smoothing may
cause the colors to run. This is a feature, not a bug. (A copyrighted
response of [your favorite commercial software company here], used by
permission.)
The ambient option sets the minimum light value a surface has if it has
no direct lighting at all. All light values are scaled from this value
to white. This effectively adjusts the depth of the shadows and sets the
overall contrast of the image.
If you selected the full color option, you have a few more choices. The
next is the haze factor. Set this to make distant objects more hazy.
Close up objects will have little effect, distant objects will have
most. 0 disables the function. 100 is the maximum effect, the farthest
objects will be lost in the mist. Currently, this does not really use
distance from the viewer, we cheat and use the y value of the original
image. So the effect really only works if the y-rotation (set earlier)
is between +/- 30.
Next, you can choose the name under which to save your Targa file. If
you have a RAM disk handy, you might want to create the file on it, for
speed. So include its full path name in this option. If you have not
set "overwrite=yes" then the file name will be incremented to avoid
over-writing previous files. If you are going to overlay an existing
Targa file, enter its name here.
Next, you may select the background color for the Targa file. The
default background on the Targa file is sky blue. Enter the Red, Green,
and Blue component for the background color you wish.
Finally, absolutely the last option (this time we mean it): you can now
choose to overlay an existing Targa-24, type 2, non mapped, top-to-
bottom file, such as created by Fractint or PVRay. The Targa file
specified above will be overlayed with new info just as a GIF is
overlayed on screen. Note: it is not necessary to use the "O" overlay
command to overlay Targa files. The Targa_Overlay option must be set to
yes, however.
You'll probably want to adjust the final colors for monochrome fill
types using light source via color cycling (p. 23). Try one of the
more continuous palettes (<F8> through <F10>), or load the GRAY palette
with the <A>lternate-map command.
Now, lie down for a while in a quiet room with a damp washcloth on your
forehead. Feeling better? Good -- because it's time to go back almost to
the top of the 3D options and just say yes to: