PovRay memo

• Sphere

                  sphere{
                    <x,y,z>, // center
                    r // radius
                    pigment{}
                    finish{}
                  }

• Cylinder

                  cylinder{
                    <x,y,z>, // bottom coordinate
                    <x,y,z>, // top coordinate
                    r // radius
                    open // Adding this removes both end faces
                    pigment{}
                    finish{}
                  }

• Cone (used to make the tip of an arrow)

                  cone{
                    <x,y,z>, // bottom coordinate
                    r // bottom radius
                    <x,y,z>, // top coordinate
                    r // top radius
                    open // Adding this removes both end faces
                    pigment{}
                    finish{}
                  }

• Line segment (used to connect multiple spheres)

                  object{
                    sphere_sweep{
                      linear_spline, // How to connect spheres. There are also cubic_spline and b_spline
                      n, // number of spheres
                      <x,y,z>, // sphere 1 coordinate
                      r // sphere 1 radius
                      <x,y,z>, // sphere 2 coordinate
                      r // sphere 2 radius
                      ...
                      pigment{}
                    }
                    finish{}
                  }

• Isosurface

                object{
                  isosurface{
                    function{f(X,Y,Z)} // f(X,Y,Z)=0 is plotted
                    contained_by{box{<x1,y1,z1>,<x2,y2,z2>}}, // plotting region
                    open // Adding this makes open surface
                    accuracy // accuracy
                    max_gradient // maximum slope
                    pigment{}
                  }
                  finish{}
                }

• Surfaces with mediating variables

                object{
                  parametric{
                    function{x(u,v)},
                    function{y(u,v)},
                    function{z(u,v)},
                    <u1,v1>,<u2,v2>
                    contained_by{box{<x1,y1,z1>,<x2,y2,z2>}}, // plotting region
                    accuracy // accuracy
                    max_gradient // maximum slope
                    pigment{}
                  }
                  finish{}
                }

• Color handling

  • color rgbf <red,green,blue,filter (lets through colors close to the original color, but not away from it) >
  • color rgbt <red,green,blue,transparency (let all colors through) >
  • color rgbft <red,green,blue,filter,transparency>

• Finish handling

  • ambient n([0:1]) : brightness or color (rgb <r,g,b>) can be specified for each texture
  • diffuse n([0:1]) : diffuse reflectance
  • brilliance n([0:1]) : gloss
  • crand n([0:1]) : roughness
  • phong n([0:1]) : intensity of bright areas (highlights) where the light source is reflected by specular reflection
  • phong_size n([1:250]) : highlight size
  • specular n([0:1]) : specular highlight intensity
  • roughness n([0.0005:1]) : specular highlight size
  • metallic n([0:1]) : intensity of metallic surface highlights
  • There are also reflection, refraction, irid (iridescence), but I have never used them

• Commonly used color mappings

                  pigment{
                    function{f(X,Y,Z)} // 0 < f < 1
                    color_map{[0 color Blue] [0.33 color Green] [0.66 color Yellow] [1 color Red]}
                  }

• make background image transparent and png output

                  background{rgbt<0,0,0,1>}

  and add +FN and +UA at output. For example

                  povray hoge.pov +FN +UA

• Specify size of output image

  For example, for a 500x400 image

                  povray hoge.pov +H500 +W400

• Example of repetitive syntax

                #declare Q=0;
                #declare dQ=0.01;
                #while (Q<100)
                  #declare P=Q*dQ;
                  something with P
                  #declare Q=Q+1;
                #end

• Shadows bother me

  In Povray, depending on the position of the light source and object, the shadow of one object may be cast on another object. If this is a concern, you can prevent the shadow from being cast by giving no_shadow to the object that casts the shadow.

• Aligning camera aspect ratio

                location <camera position>
                look_at <look at position>
                right <0,1,0>
                up <0,0,1>