// Exemplo de arquivo de descricao de cena para POV-ray
// Last edited on 2017-05-07 20:10:09 by stolfilocal

// ======================================================================
// CORES E TEXTURAS

background{ color rgb < 0.75, 0.80, 0.85 > }

#declare tx_plastico = 
  texture{
    pigment{ color rgb < 0.10, 0.80, 1.00 > }
    finish{ diffuse 0.8 ambient 0.1 specular 0.5 roughness 0.005 }
  }

#declare tx_fosca = 
  texture{
    pigment{ color rgb < 1.00, 0.80, 0.10 > }
    finish{ diffuse 0.9 ambient 0.1 }
  }

#declare tx_espelho = 
  texture{
    pigment{ color rgb < 1.00, 0.85, 0.30 > }
    finish{ diffuse 0.2 reflection 0.7*< 1.00, 0.85, 0.30 > ambient 0.1 }
  }

#declare tx_vidro = 
  texture{
    pigment{ color rgb < 0.85, 0.95, 1.00 > filter 0.70 }
    finish{ diffuse 0.03 reflection 0.25 ambient 0.02 specular 0.25 roughness 0.005 }
  }


#declare tx_xadrez =
  texture{
    pigment{ checker color rgb < 0.10, 0.32, 0.60 >, color rgb < 1.00, 0.97, 0.90 > }
    finish{ diffuse 0.9 ambient 0.1 }
    scale 2.0
  }

// ======================================================================
// DESCRIÇÃO DA CENA 

#macro interpolar(t0, v0, t1, v1, tt)
	#local r = (tt - t0)/(t1 - t0);
	#local s = 1 - r;
	#local vv = s*v0 + r*v1;
	vv
#end

#macro arcobezier(t0, t1, A, B, C, D, tt)
	#local AB = interpolar(t0, A, t1, B, tt);
	#local BC = interpolar(t0, B, t1, C, tt);
	#local CD = interpolar(t0, C, t1, D, tt);

	#local ABC = interpolar(t0, AB, t1, BC, tt);
	#local BCD = interpolar(t0, BC, t1, CD, tt);

	#local ABCD = interpolar(t0, ABC, t1, BC, tt);

	ABCD
#end

#macro Corda(centro, n, lado)
	#declare i = 0;
	#declare tt = 0.0;
	union {
		#while(i < n)
			#if ((tt >= 0) & (tt < 0.25))
				#declare centro = arcobezier(0, 0.25, <0,0,0>, <0.2,0,0.1>, <0.1,0,0.1>, <0.5,0,0.25>, tt);
			#end
			#if ((tt >= 0.25) & (tt < 0.5))
				#declare centro = arcobezier(0.25, 0.5, <0.5,0,0.25>, <-0.1,0,-0.1>, <-0.2,0,-0.1>, <-0.5,0,-0.5>, tt);
			#end 
			#if ((tt >= 0.5) & (tt < 0.75))
				#declare centro = arcobezier(0.5, 0.75, <-0.5,0,-0.5>, <0.25,0,0.5>, <0.5,0,0.5>, <0.5,0,-0.5>, tt);
			#end
			#if ((tt >= 0.75) & (tt < 1))
				#declare centro = arcobezier(0.75, 1, <0.5,0,-0.5>, <0.25,0,0.5>, <0.5,0,0.5>, <0.0,0,0>, tt);
			#end

			sphere{ lado*centro , 0.2 texture { tx_fosca }}

			#declare tt = tt + 1/n;
			#declare i = i + 1;
		#end
	}
#end

Corda(0, 2000, 20)

#include "camlight.inc"
#declare centro_cena = < 0, 0, 5 >;
#declare raio_cena = 20;
#declare dir_camera = < 10.00, 30.00, 5.00 >;
#declare dist_camera = 5*raio_cena;
#declare intens_luz = 1.20;
camlight(centro_cena, raio_cena, dir_camera, dist_camera , z, intens_luz)