On 4/9/20 3:55 AM, William F Pokorny wrote:
> On 4/8/20 2:23 PM, Bald Eagle wrote:
...
> 
> Anyway, wild dreams. Today. Off to kill the spotted pattern, f_spotted, 
> f_bumps, f_bozo and change bozo's inbuilt default color_map to black and 
> white. Simpler things first.
> 
>

Bald Eagle's question in advanced about the slope pattern got me to 
thinking it might be helpful to talk more about why I am dropping all 
the continuous pattern default color_maps back to black(0) to white(1).

It's the case today some patterns have default color maps and others 
don't in the official POV-Ray implementations. For example, though bozo, 
bump and spotted are all really just calls to 3d noise; Only bozo has a 
many color default color map. The radial pattern has a many color 
default, the granite pattern does not and so on. At least some of this 
behavior is documented, but I've never done a complete survey to see if 
it's all there and correct.

I ran into considerable confusion back when I was playing with the 
peeling paint isosurface stuff and trying to come up with ways to 
implement the method on the fly. I was trying something similar to what 
you are trying with the color channels.

With access to the five color channels (and v3.8's blend mode/gamma for 
the rgb channels) what we have is a powerful way to 'skew' a single 
function's resulting values. What happened with me as I was working is I 
kept commenting out my color_map line while debugging as in:

// color_map { CM_skewFunctionResults }

but I wasn't always getting then a default black to white color_map I 
expected, but sometimes a - whatever colors - internally set up one.

I expect one can run into similar confusion working with media densities 
and defaulted many color maps.

In my personal povr all continuous patterns will default to black to 
white maps - though I've only modified bozo and radial thus far.

Aside: I think it probably makes sense for the block patterns to have 
default color maps. I cannot think of a good reason for continuous 
patterns to have defaults other than black to white. Is there, or was 
there one back in the early days of many gammas or something?

Aside 2: I have modified the default brick (block pattern) colors for 
the 2.2 to 1.0 default gamma change. If you run brick with the default 
color map the result is very washed out compared to v3.6 and prior 
results. True too for our color include which I plan to lose or replace 
entirely in povr. New users should not be pulling colors out of colors 
inc. Those color definitions today correspond to no common standard that 
I can see. (Wikipedia has a very complete set of color names and common 
value definitions if you've not come across it: 
https://en.wikipedia.org/wiki/Lists_of_colors)

Bill P.

Post a reply to this message