marble pattern is very similar to the
gradient x pattern. The gradient pattern uses a
ramp_wave wave type which means it uses colors from the color map from 0.0 up to 1.0 at location
x=1 but then jumps back to the first color for x > 1 and repeats the pattern again and again. However the
pattern uses the
triangle_wave wave type in which it uses the color map from 0 to 1 but then it reverses
the map and blends from 1 back to zero. For example:
[0.0 color Yellow]
[1.0 color Cyan]
This blends from yellow to cyan and then it abruptly changes back to yellow and repeats. However replacing
marble smoothly blends from yellow to cyan as the x coordinate goes from 0.0 to 0.5 and
then smoothly blends back from cyan to yellow by x=1.0.
Earlier versions of POV-Ray did not allow you to change wave types. Now that wave types can be changed for most any
pattern, the distinction between
gradient x is only a matter of default wave
When used with turbulence and an appropriate color map, this pattern looks like veins of color of real marble, jade
or other types of stone. By default, marble has no turbulence.
marble pattern has a default color_map built in that results in a red, black and white pattern
with smooth and sharp transitions.