The inside() test for linear_sweep prisms appears to be problematic, 
potentially creating artifacts in difference or intersection CSG if 
other participating objects have surfaces coinciding with one of the 
prism edged:


camera {
   right    -x
   up        y*image_height/image_width
   location  <-24,19,12>
   look_at   <0,0,0>
}

light_source { <100,200,100> color rgb 1 }

plane { y, -2 pigment { color rgb 1 } }


#declare KeyValue = 1.366; // pick any you like

difference {
   prism {
     linear_sweep -0.5,0.5, 4

     <-3,20-17>,
     <-3,KeyValue>,
     <-6,-3>,
     <-0,-5>
   }
   intersection {
     cylinder { <-7,-0.51,1>, <-7, 0.51,1>, 4.0 }
     plane { z, KeyValue }
   }
   pigment { color rgb 0.5 }
}

Post a reply to this message