From a scene file saved in 2005, I have a piece of code containing an isosurface
with a smooth twist. I would like to extend this from 1/4 turn into many turns.
Ultimatly it would be part of an ornate fence.

// +w320 +h240
background { color rgb <1.000,1.000,1.000> }

#declare Default_Red =
texture {
 pigment {
  color rgbft <1.000,0.000,0.000,0.000,0.000>
 }

}

#default{ texture{ Default_Red } }

#declare Gray_80_ =
texture {
 pigment {
  color rgbft <0.800,0.800,0.800,0.000,0.000>
 }

}

#declare Camera =
camera {
 perspective
 location <-3.377,5.850,-12.283>
 up y
 right 1.333*x
 angle 15.096
 sky <0.136,0.904,0.407>
 look_at < 0.623, -0.150, -0.283 >
}  // end Camera

#local fn_A=function(x){abs(x)-.5};
#local fn_B=function{abs(z)-3/16/2};
#local fn_C=function{abs(y)-.5};
#local N=.25;
#local fn_Smooth=function(x){x*x*x*(10+x*(6*x-15))};
#local fn_twistY=function{z*sin(fn_Smooth(x)*2*pi*N) +
y*cos(fn_Smooth(x)*2*pi*N)};
#local fn_twistZ=function{z*cos(fn_Smooth(x)*2*pi*N) -
y*sin(fn_Smooth(x)*2*pi*N)};
#local
fn_twist_Box=function{max(fn_A(x-.5),fn_B(x,fn_twistY(x,y,z),fn_twistZ(x,y,z)),fn_C(x,fn_twistY(x,y,z),fn_twistZ(x,y,z)
))};
isosurface {
   function {
      fn_twist_Box(x-.5,y,z)
   }
   contained_by {box{<.5,-.5,-.5>,<1.5,.5,.5>}}
   threshold 0
   accuracy 0.001
   max_gradient 1.58
   max_trace 9

scale <1,1,1>
rotate <0,0,0>
translate <0,0,0>
}


light_source {  // Light_Source
 < 0.000000, 0.000000, 0.000000 >, color rgb <1.000,1.000,1.000>
 fade_power 0.000
 fade_distance 100.000
 media_attenuation off
 media_interaction on
 translate <3.000000,10.000000,-12.500000>
}  // end Light_Source

union {  // CSG0
 box {  // Box0
  < -1.2500000, -0.5000000, -0.0937500 >, < 1.2500000, 0.5000000, 0.0937500 >
  translate <-0.750000,0.000000,0.000000>
 }  // end Box0

 box {  // Box1
  < -1.0000000, -0.0937500, -0.5000000 >, < 1.0000000, 0.0937500, 0.5000000 >
  translate <2.500000,0.000000,0.000000>
 }  // end Box1

 texture{ Gray_80_ }
}  // end CSG0


camera{ Camera }
// end code


I can change the cross section to:
#local fn_B=function{abs(z)-.25};
#local fn_C=function{abs(y)-.25};
to get my 1/2" wrought iron bar, but i'm stumped at getting multiple turns over
a desired length.
Help would be appreciated.

Stephen S

Post a reply to this message