背景となる部分を描画します。
//**********************************************************************************
#local P_lightening =
pigment { granite
turbulence 0.49
color_map { [0.00 rgbf < 1,1,1,1 > ]
[0.28 rgbf < 1,1,1,1 > ]
[0.29 rgbf < 0,1,0.5,0 > ]
[0.30 rgbf < 0.5,0,1,0 > ]
[0.32 rgbf < 1,0.5,0,0 > ]
[0.33 rgbf < 1,1,1,1 > ]
[1.00 rgbf < 1,1,1,1 > ] } rotate 180*y }
sky_sphere { pigment { P_lightening scale 4 } rotate 180*x translate < 2.4,-3.8,-1.2 > }
//**********************************************************************************
