#declare ImageWidth = 160;
#declare ImageHeight = 120;
#declare MaxRecLev = 5;
#declare AmbientLight = <.2,.2,.2>;
#declare BGColor = <0,0,0>;
These lines just declare some identifiers defining some general values which will be used later in the code. The
keyword we use here is
#declare and it means that we are declaring a global identifier, which will be
seen in the whole code.
As you can see, we declare some identifiers to be of float type and others to be of vector type. The vector type
identifiers are, in fact, used later for color definition (as their name implies).
ImageHeight define the resolution of the image we are going to render.
Note: this only defines the resolution of the image we are going to render in our SDL
(ie. into the array we will define later); it does not set the resolution of the image which POV-Ray will render.
MaxRecLev limits the maximum number of recursive reflections the code will calculate. It is
equivalent to the
max_trace_level value in
global_settings which POV-Ray uses to raytrace.
AmbientLight defines a color which is added to all surfaces. This is used to "lighten
up" shadowed parts so that they are not completely dark. It is equivalent to the
BGColor defines the color of the rays which do not hit anything. It is equivalent to the
block of POV-Ray.