ocaml/povray tutorial

Beginning with povray and with the ocaml programming language.

First download and compile pov-bind. This is an ocaml interface for povray.

Check that ocaml and povray are correctly installed.

This tutorial should be compatible with "pov-bind" versions "0.11" or "0.12".

Start a new script with the file-extension '.ml'.

You can start by defining a shorter alias for the main module "Povray" (at the beginning of the file):

module Pov = Povray

You can then define a color for the background:

let bg_color = PovColor.RGB(0.2, 0.1, 0.4)

Create a new empty-scene with the function Pov.new_scene:

let () =
  let sc = Pov.new_scene () in
  let sc = Pov.add_background sc ~color:bg_color in
  let sc = Pov.add_camera sc ~location:cam_loc ~look_at () in

  Pov.print_scene sc;
;;

You can then add a background with the background-color "bg_color", and a camera with the camera-location and where it should look at:

let cam_loc = (1.8, 4.8, 2.4)
let look_at = (0.0, 0.6, 0.0)

These 2 vars should be defined before to be used, this is why you should place these 2 definitions before the call to the function "Pov.add_camera".

The complete script should then look like this:

module Pov = Povray
module PovColor = Pov.Color

let bg_color = PovColor.RGB(0.2, 0.1, 0.4)

let cam_loc = (1.8, 4.8, 2.4)
let look_at = (0.0, 0.6, 0.0)

let () =
  let sc = Pov.new_scene () in
  let sc = Pov.add_background sc ~color:bg_color in
  let sc = Pov.add_camera sc ~location:cam_loc ~look_at () in

  (* shapes can be added here *)

  Pov.print_scene sc;
;;

If this script is in a file called "scene1.ml", you should be able to create the *.pov file "scene1.pov" like this:

ocaml -I ../src povray.cma scene1.ml > scene1.pov

Replace ../src by a path where to find the file povray.cma.

This command should produce the file scene1.pov.

povray +W360 +H220 -V +A +Iscene1.pov

This command should produce the file "scene1.png":

The scene looks empty with only the background color, because it doesn't contain any shape yet.

We can add a light-source and a sphere:

module Pov = Povray
module PovColor = Pov.Color

let bg_color = PovColor.RGB(0.2, 0.2, 0.8)
let light_color = PovColor.RGB(1.0, 1.0, 1.0)

let cam_loc = (1.8, 4.8, 2.4)
let look_at = (0.0, 0.6, 0.0)

let () =
  let sc = Pov.new_scene () in
  let sc = Pov.add_background sc ~color:bg_color in
  let sc = Pov.add_camera sc ~location:cam_loc ~look_at () in

  let sc = Pov.add_light_source sc ~location:(6.0, 16.0,  4.0) ~color:light_color in

  let color1 = PovColor.RGB(0.2, 1.0, 0.4) in
  let texture = Pov.new_texture ~color:color1 () in

  let sc =
    Pov.add_sphere sc
       ~center:(0.0, 0.2, 0.0)
       ~radius:1.6
       ~texture () in

  Pov.print_scene sc;
;;

The second .pov file scene2.pov will produce this image:

In the next script, we add an "ambient-light" and a "plane" to represent the ground, so that the sphere doens't look like to fly. We apply a "blue-checker" with 2 colors on the plane. With this new script scene3.ml, we get the .pov file scene3.pov which gives the image:

  (* ambient-light *)
  let sc = Pov.add_ambient_light sc ~color:(0.2, 0.1, 0.8) in

  (* blue-checker *)
  let texture =
    let color1 = PovColor.RGB(0.10, 0.30, 0.80) in
    let color2 = PovColor.RGB(0.12, 0.34, 0.86) in
    Pov.new_checker ~color1 ~color2 ()
  in
  let sc = Pov.add_plane sc ~norm:(0, 1, 0) ~dist:(0) ~texture () in

You can find the api-doc of the version "0.11" there:

• Povray module v-0.11

We can also draw cylinders, boxes, cones and torus shapes, with predefined functions.

Custom shapes can also be defined with triangles.

This is possible to define triangles like this way:

let triangles =
  [
    ( (-0.2, 0.0,  0.2), (0.0, 1.4, 0.0), ( 0.2, 0.0,  0.2) );
    ( ( 0.2, 0.0,  0.2), (0.0, 1.4, 0.0), ( 0.2, 0.0, -0.2) );
    ( ( 0.2, 0.0, -0.2), (0.0, 1.4, 0.0), (-0.2, 0.0, -0.2) );
    ( (-0.2, 0.0, -0.2), (0.0, 1.4, 0.0), (-0.2, 0.0,  0.2) );
  ]

Every triangle is defined with three vertices. A vertex is defined with x, y, and z coordinantes (x, y, z).

The set of coordinates above creates a pyramid shape.

Here (0.0, 1.4, 0.0) is the top of the "pyramid".

We need 4 triangles to define this "pyramid".

The mesh created with these coordinates can be added to the "scene" with the function:

  PovMesh.add_mesh sc ~triangles ~texture ~translate ~rotate ()

The coordinates can be used several times to create several meshes, with different locations, that can be defined with the ~translate parameter.