#version 3.8;
global_settings {assumed_gamma 1.0}

    camera{orthographic
         //location< 0, 20, 0>        // Sweep portion missing
         //location< 0.0001, 20, 0>   // Renders OK
           location< 0, 20, 0.0001>   // Renders OK
           look_at <0,0,0>
           direction -y
           sky z
           up z * 4
           right x * 4}

//-------- Equivalent orthographic camera as user_defined camera ------
//  #declare OrthoMult = 4.0;
//  camera {  // Proves not related to 'plane' of orthographic camera
//      user_defined
//      location {
//        function { OrthoMult*x*4/3 }
//        function { 20  }
//        function { OrthoMult*y }
//      }
//      direction {
//      //function { 0 + 1e-4 } // Renders OK
//        function { 0 }        // Sweep portion missing
//        function { -1 }
//        function { 0 }
//      }
//  }

light_source{<10,10,10>*100000 color srgb 1}

#declare green_col = srgb <8, 59, 4 >/256 ;
#declare brown_col = srgb <82, 62, 9> / 256 ;

#declare T_tent = texture{pigment{ dents color_map{
                                                    [0.0 green_col]
                                                    [0.2 green_col]
                                                    [0.21 brown_col]
                                                    [0.99 brown_col]
                                                    [1.0 green_col]
                                                   }
                                  scale 0.2 rotate 90*x
                                 }
                          normal{agate bump_size 0.25}
                          finish{specular 0.1 roughness 0.9 }
                         }

#declare Pyramid = prism{
                         conic_sweep linear_spline 1,0.5,
                      // 5 <-1,1>,<1,1>,<1,-1>,<-1,-1>,<-1,1>
                         5 <-1,1>,<-1,-1>,<1,-1>,<1,1>,<-1,1>
                         open  // Added to eliminate caps
                         sturm
                         rotate 180*x translate 1*y}

// Note clockwise point order turns prism inside-out
// and interior_texture added below will shows. Also
// changes the behavior of your normal {} block above.

object{
    Pyramid
    texture{T_tent}
    interior_texture {pigment {color rgb <1,0,0>} }
}