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Subject: 
Re: Sand Green and POV
Newsgroups: 
lugnet.cad, lugnet.inst
Date: 
Mon, 20 Jan 2003 20:11:45 GMT
Viewed: 
3462 times
  
OK got some stuff figured out...
Color 295 looks close to Sand Green, its on the second page of colors after
256, top row last color.  Sand green ~= gray + green ==> 7 + 2*16 + 256 =
295. See .dat and .pov examples below.

Notice that the color table is laid out in a special way. There are 16
colors defined in MLCAD (or maybe LDraw???). Someone, somehow, somewhere,
decided that if you dither two of these predefined colors (50%/50%), that
you can get a "well defined" table that expands the palette. Which is
exactly what colors 256 thru 511 are.

The table layout is 8 columns wide and 16 rows tall (8 pages). Every two
rows is based on the same Color2 and each column adds the next ordinal color
based on the original 16 colors.

For example the first row of colors are based on color 0 (black) adding
colors 0-7:
blk + blk ==> 0 + 0*16 + 256 = 256
blue + blk ==> 1 + 0*16 + 256 = 257
green + blk ==> 2 + 0*16 + 256 = 258
teal + blk ==> 3 + 0*16 + 256 = 259
red + blk ==> 4 + 0*16 + 256 = 260
etc...

The second row is still based on color 0 (black) but adding colors 8-15:
drk gray + blk ==> 8 + 0*16 + 256 = 264
lt blue + blk ==> 9 + 0*16 + 256 = 265
lt green + blk ==> 10 + 0*16 + 256 = 266
cyan + blk ==> 11 + 0*16 + 256 = 267
lt red + blk ==> 12 + 0*16 + 256 = 268
etc...

The third row starts all over but is now based on color 1 (blue)
blk + blue ==> 0 + 1*16 + 256 = 272
blue + blue ==> 1 + 1*16 + 256 = 273
green + blue ==> 2 + 1*16 + 256 = 274
teal + blue ==> 3 + 1*16 + 256 = 275
red + blue ==> 4 + 1*16 + 256 = 276
etc... etc... :)

There is a method to this layout based on the equation that Steve Bliss
supplied several months ago (http://news.lugnet.com/trains/?n=17404), which
is: Color1 + Color2 * 16 + 256. Also note that the line color is based on
Color1.

Soooo, in order to find a color (well and easy one like sand green which is
close to green + gray) you go to the "greens" which is the third set of
colors starting on the 5th row (top of page 2) and go to the 8th swatch
(color7 == gray) and you find color 295. BTW I don't think that there is a
automated way to maintain a true RGB color value from MLCad to POV thru L3P,
see Lar's post:(http://news.lugnet.com/cad/?n=8533)

It's just that easy! Color-o-matic 76! ;)

I got a couple of comments.
1) Each color is repeated twice, not too efficient (ignoring that the line
color changes, which in POV is irrelevant).
2) Why didn't you guys just use RGB values, with recommendations for
standard colors? CLUT died in the 90's man! :)

SteveB
PNLTC

.DAT file
" 0 Test Color: Sand Green
" 0 Author: SEBarile
" 0 The color 295 looks close
" 0 sand green ~= gray + green ==> 7 + 2*16 + 256 = 295
" 1 4 0 -32 30 1 0 0 0 1 0 0 0 1 3005.DAT
" 1 295 0 -32 0 1 0 0 0 1 0 0 0 1 3005.DAT
" 1 1 0 -32 -30 1 0 0 0 1 0 0 0 1 3005.DAT
" 0

.POV color def...
#ifndef (Color295)
#declare Color295 = #if (version >= 3.1) material { #end texture {
pigment { rgb <0.4,0.654902,0.454902> }
finish { ambient AMB diffuse DIF }
#if (QUAL > 1)
finish { phong 0.5 phong_size 40 reflection 0.08 }
#if (BUMPS) normal { BUMPNORMAL } #end
#end
} #if (version >= 3.1) } #end
#end



Message has 1 Reply:
  Re: Sand Green and POV
 
(...) Great! <snip> (...) Uh... I was going to suggest this but LPub doesn't support them (blush ;-) Time to add *that* to the wish list. Kevin (...) (22 years ago, 20-Jan-03, to lugnet.cad, lugnet.inst)

Message is in Reply To:
  Re: Sand Green and POV
 
Here's some interesrting reading that dosen't answer the question but is very related (just trying to keep a path for historical sake). The thread wanders, but from here down is about CLUTs and MLCad custom (...) (22 years ago, 20-Jan-03, to lugnet.cad, lugnet.inst)

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