Catmull–Clark subdivision surface/OCaml: Difference between revisions
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Below is a program in OpenGL which displays a cube subdivided 2 times with the ''Catmull–Clark surface subdivision''
{{libheader|glMLite}}
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(6, 1, 2, 4);
(* comment some of these faces to see how
the
*)
|]
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Revision as of 00:54, 16 August 2010
Here is the file dynar.ml (module Dynar), it implements a structure similar to arrays but with which we can push a new element at the end.
<lang ocaml>type 'a t = { mutable ar: 'a array; mutable n: int; mutable max_n: int }
let of_array ar =
let n = Array.length ar in { ar=ar; n=n; max_n=n }
let of_list li =
of_array (Array.of_list li)
let push da v =
if da.n < da.max_n then (da.ar.(da.n) <- v; da.n <- succ da.n) else begin let old_get = Array.unsafe_get da.ar in let old_max = da.max_n in let new_size = succ da.max_n * 2 in let new_ar = Array.init new_size (fun i -> if i < old_max then old_get i else v) in da.ar <- new_ar; da.n <- succ da.n; da.max_n <- new_size; end
(* returns the index of the item that has been pushed *) let pushi da v =
let i = da.n in push da v; (i)
let to_array da =
Array.init da.n (Array.unsafe_get da.ar)</lang>
Below is a program in OpenGL which displays a cube subdivided 2 times with the Catmull–Clark surface subdivision algorithm.
You can compile everything together with:
ocamlopt -c dynar.ml ocamlopt -c subsurf.ml ocamlopt -I +glMLite GL.cmxa Glu.cmxa Glut.cmxa dynar.cmx subsurf.cmx main.ml -o catmull.opt
<lang ocaml>open GL open Glu open Glut
let points0 = [|
(-0.5, 0.5, 0.5); (-0.5, -0.5, 0.5); (0.5, -0.5, 0.5); (0.5, 0.5, 0.5); (0.5, -0.5, -0.5); (0.5, 0.5, -0.5); (-0.5, -0.5, -0.5); (-0.5, 0.5, -0.5);
|]
let faces0 = [|
(0, 1, 2, 3); (3, 2, 4, 5); (5, 4, 6, 7); (7, 0, 3, 5); (7, 6, 1, 0); (6, 1, 2, 4); (* comment some of these faces to see how the algorithm handles surfaces with holes *)
|]
let points1, faces1 = Subsurf.catmull points0 faces0 ;;
let points2, faces2 = Subsurf.catmull points1 faces1 ;;
let b_down = ref false
let anglex = ref (-64)
let angley = ref (-19)
let xold = ref 0
let yold = ref 0
let display () =
glClear [GL_COLOR_BUFFER_BIT; GL_DEPTH_BUFFER_BIT];
glLoadIdentity();
glTranslate ~x:(0.0) ~y:(0.0) ~z:(-3.0);
glRotate ~angle:(float(- !angley)) ~x:1.0 ~y:0.0 ~z:0.0; glRotate ~angle:(float(- !anglex)) ~x:0.0 ~y:1.0 ~z:0.0;
let draw points faces = let put_point i = glVertex3v points.(i) in glBegin GL_QUADS; Array.iter (fun (a,b,c,d) -> put_point a; put_point b; put_point c; put_point d; ) faces; glEnd(); in glColor3 0.4 0.4 0.4; draw points0 faces0; glColor3 0.4 0.4 0.4; draw points1 faces1; glColor3 0.9 0.9 0.9; draw points2 faces2;
glFlush(); glutSwapBuffers();
let reshape ~width ~height =
glMatrixMode GL_PROJECTION; glLoadIdentity(); gluPerspective 30. (float width /. float height) 2. 30.; glViewport 0 0 width height; glMatrixMode GL_MODELVIEW; glutPostRedisplay();
let keyboard ~key ~x ~y =
match key with | '\027' | 'q' -> exit(0) | _ -> ()
let mouse ~button ~state ~x ~y =
match button, state with | GLUT_LEFT_BUTTON, GLUT_DOWN -> b_down := true; xold := x; yold := y; | GLUT_LEFT_BUTTON, GLUT_UP -> b_down := false; | _ -> ()
let motion ~x ~y =
if !b_down then begin anglex := !anglex + (!xold - x); angley := !angley + (!yold - y); glutPostRedisplay(); end; xold := x; yold := y;
let () =
ignore(glutInit Sys.argv); glutInitDisplayMode[GLUT_RGB; GLUT_DOUBLE; GLUT_DEPTH]; glutInitWindowPosition ~x:100 ~y:100; glutInitWindowSize ~width:640 ~height:480; ignore(glutCreateWindow ~title:Sys.argv.(0));
glEnable GL_DEPTH_TEST; glPolygonMode GL_FRONT_AND_BACK GL_LINE; glClearColor 0.2 0.2 0.2 0.0;
glutDisplayFunc ~display; glutReshapeFunc ~reshape; glutKeyboardFunc ~keyboard; glutMouseFunc ~mouse; glutMotionFunc ~motion; glutMainLoop();
- </lang>