polig_curve (
N, // number of sides
mj_rad_A, // radius of the central semicircle
mj_rad_B, // radius of the arc in the vertex
min_rad_c, // thickness
convex, // set concavity (on/off)
design // included 4 little variations on the shape's geometry
)

Download: polig_curve.mcr

[Show as slideshow]

Possibly one of the first macros that were written for Pov-Ray when  the conditional statements were implemented, although I don’t know who was the first to devise it or write it. My CAT macro for scanning of objects is based on the idea that was used here.

• Before use you must declare the object to be cut in pieces:
  (p.e #declare My_Box = box{…})
• The macro will create N-copies of the object in question, one for each slice in which it is to chop.
• Each “piece” of the object is achieved by CSG intersection between the original object and a box that moves up to each slice, and sideways (set by the rnd_amount parameter) to simulate a bit of randomness.

[Show as slideshow]

Download (right button and “Save target as”): CW_angle.mcr

/*
Takes a pigment as input and returns the pigment placed
at A degrees in the cromatic wheel
pigment {CW_angle(Red,180} // returns cyan
pigment {CW_angle(Red,120} // returns green
pigment {CW_angle(Red,240} // returns blue
*/
 #macro CW_angle (COLOR,A)
   #local RGBFT = color COLOR;
   #local R = (RGBFT.red);
   #local G = (RGBFT.green);
   #local B = (RGBFT.blue);
   #local Min = min(R,min(G,B));
   #local Max = max(R,max(G,B));
   #local Span = Max-Min;
   #local H = CRGB2H (<R,G,B>, Max, Span);
   #local S = 0; #if (Max!=0) #local S = Span/Max; #end

   #local P = <H+A,S,Max,(RGBFT.filter),(RGBFT.transmit)> ;

   #local HSVFT = color P ;
#local H = (HSVFT.red);
   #local S = (HSVFT.green);
   #local V = (HSVFT.blue);
   #local SatRGB = CH2RGB(H);
   #local RGB = ( ((1-S)*<1,1,1> + S*SatRGB) * V );
   rgb <RGB.red,RGB.green,RGB.blue,(HSVFT.filter),
       (HSVFT.transmit)>
#end

Recommended links:

• Color Theory
• Color Wheel
• Review of the teory of color. (in spanish)

pd. Thanks to user Alain for its help in news.povray.org

Depending on your choice the macro returns one of the following values ​​in a polygon of N sides and side L:

#macro Trigon(N,L,D)
#switch (D)
#case (1) #local Valor = (L/2) / tand(180/N) ; #break
#case (2) #local Valor = (L/2) / sind(180/N) ; #break
#case (3) #local Valor = (L/2) ; #break
#case (4) #local Valor = 360/N ; #break
#case (5) #local Valor = 180/N ; #break
#case (6) #local Valor = (90-(180/N)) ; #break
#case (7) #local Valor = (90-(180/N))*2 ; #break
#case (8) #local Valor = 360-Trigon(N,L,5) ; #break
#case (9)
 #if (odd(N)=true) #local Valor = Trigon(N,L,1)+Trigon(N,L,2) ;
#else #local Valor = Trigon(N,L,1)*2; #end #break
#case (10) #local Valor = Trigon(N,L,2)*2 ; #break
#case (11) #local Valor = L*N ; #break
#case (12) #local Valor = N*((L/2)*Trigon(N,L,1)); #break
#case (13) #local Valor = 2*((L/2)/sind(180/N))*sin(360/N); #break
#end
  Valor
#end

This program was first published in 1991 and has its origins in a program called DKBTrace 2.12 created by David K. Buck and Aaron Collins for the AMIGA environment. The full story can be found on the official website of the program (here), but can be summarized in a group of fans to the synthetic image (grouped under the POV Team) sought permission from David K. Buck to continue the updating for a program which David had no time to improve. The list of people who have collaborated altruistically over the years by modifying the code, writing scenes, tutorials or include files is almost endless.

Recommended:

• The Pov-Ray
• The Pov-Ray Hall of Fame
• Oyonale (Gilles Tran)
• La persistencia de la Ignorancia (Jaime Vives Piqueres)
• Andrea Lohmüller + Friedrich A. Lohmüller