77 lines
2.1 KiB
Text
77 lines
2.1 KiB
Text
#directory "+cairo"
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#load "bigarray.cma"
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#load "cairo.cma"
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let img_name = "/tmp/fractree.png"
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let width = 480
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let height = 640
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let level = 9
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let line_width = 4.0
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let color = (1.0, 0.5, 0.0)
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let pi = 4.0 *. atan 1.0
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let angle_split = pi *. 0.12
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let angle_rand = pi *. 0.12
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let () =
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Random.self_init();
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let surf = Cairo.image_surface_create Cairo.FORMAT_RGB24 ~width ~height in
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let ctx = Cairo.create surf in
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Cairo.set_antialias ctx Cairo.ANTIALIAS_SUBPIXEL;
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Cairo.set_line_cap ctx Cairo.LINE_CAP_ROUND;
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let draw_line (x,y) (dx,dy) =
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Cairo.move_to ctx x (float height -. y);
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Cairo.line_to ctx dx (float height -. dy);
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Cairo.stroke ctx;
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in
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let set_color (r,g,b) v =
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Cairo.set_source_rgb ctx ~red:(r *. v) ~green:(g *. v) ~blue:(b *. v);
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in
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let trans_pos (x,y) len angle =
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let _x = cos angle
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and _y = sin angle in
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(x +. (_x *. len),
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y +. (_y *. len))
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in
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let rec loop ~level ~pos ~line_width ~line_len
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~angle ~angle_split ~angle_rand ~intc =
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if level > 0 then begin
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(* draw the current segment *)
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Cairo.set_line_width ctx line_width;
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set_color color intc;
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let pos_to = trans_pos pos line_len angle in
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draw_line pos pos_to;
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(* evolution of the parameters *)
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let line_width = line_width *. 0.8
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and line_len = line_len *. 0.62
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and angle_split = angle_split *. 1.02
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and angle_rand = angle_rand *. 1.02
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and intc = intc *. 0.9
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in
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let next_loop =
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loop ~level:(pred level) ~pos:pos_to ~intc
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~line_width ~line_len ~angle_split ~angle_rand
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in
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(* split *)
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let angle_left = angle +. angle_split +. Random.float angle_rand
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and angle_right = angle -. angle_split -. Random.float angle_rand
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in
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next_loop ~angle:angle_left;
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next_loop ~angle:angle_right
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end
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in
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let pos = (float width *. 0.5, float height *. 0.1)
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and line_len = float height *. 0.3
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in
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loop ~level ~pos ~angle:(pi /. 2.0)
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~angle_split ~angle_rand
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~line_width ~line_len ~intc:1.0;
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Cairo_png.surface_write_to_file surf img_name
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(*Cairo_png.surface_write_to_channel surf stdout*)
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