1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
|
(*
Alpha color values demonstration.
Copyright (C) 2008 Hazen Babcock
Copyright (C) 2008, 2010 Hezekiah M. Carty
This file is part of PLplot.
PLplot is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published
by the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
PLplot is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with PLplot; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
This example will only really be interesting when used with devices that
support or alpha (or transparency) values, such as the cairo device family.
*)
open Plplot
let red = [|0; 255; 0; 0|]
let green = [|0; 0; 255; 0|]
let blue = [|0; 0; 0; 255|]
let alpha = [|1.0; 1.0; 1.0; 1.0|]
let px = [|0.1; 0.5; 0.5; 0.1|]
let py = [|0.1; 0.1; 0.5; 0.5|]
let pos = [|0.0; 1.0|]
let rcoord = [|1.0; 1.0|]
let gcoord = [|0.0; 0.0|]
let bcoord = [|0.0; 0.0|]
let acoord = [|0.0; 1.0|]
let rev = [|false; false|]
let () =
plparseopts Sys.argv [PL_PARSE_FULL];
plinit ();
plscmap0n 4;
plscmap0a red green blue alpha;
(* Page 1:
This is a series of red, green and blue rectangles overlaid
on each other with gradually increasing transparency. *)
(* Set up the window *)
pladv 0;
plvpor 0.0 1.0 0.0 1.0;
plwind 0.0 1.0 0.0 1.0;
plcol0 0;
plbox "" 1.0 0 "" 1.0 0;
(* Draw the boxes *)
for i = 0 to 8 do
let icol = i mod 3 + 1 in
(* Get a color, change its transparency and
set it as the current color. *)
let r, g, b, a = plgcol0a icol in
plscol0a icol r g b (1.0 -. float_of_int i /. 9.0);
plcol0 icol;
(* Draw the rectangle *)
let translate a =
Array.map (fun x -> x +. 0.5 /. 9.0 *. float_of_int i) a
in
plfill (translate px) (translate py);
done;
(* Page 2:
This is a bunch of boxes colored red, green or blue with a single
large (red) box of linearly varying transparency overlaid. The
overlaid box is completely transparent at the bottom and completely
opaque at the top. *)
(* Set up the window *)
pladv 0;
plvpor 0.1 0.9 0.1 0.9;
plwind 0.0 1.0 0.0 1.0;
(* Draw the boxes. There are 25 of them drawn on a 5 x 5 grid. *)
for i = 0 to 4 do
(* Set box X position *)
let px0 = 0.05 +. 0.2 *. float_of_int i in
let px1 = px0 +. 0.1 in
let px = [|px0; px1; px1; px0|] in
(* We don't want the boxes to be transparent, so since we changed
the colors transparencies in the first example we have to change
the transparencies back to completely opaque. *)
let icol = i mod 3 + 1 in
let r, g, b, a = plgcol0a icol in
plscol0a icol r g b 1.0;
plcol0 icol;
for j = 0 to 4 do
(* Set box y position and draw the box. *)
let py0 = 0.05 +. 0.2 *. float_of_int j in
let py2 = py0 +. 0.1 in
let py = [|py0; py0; py2; py2|] in
plfill px py;
done
done;
let px = [|0.0; 1.0; 1.0; 0.0|] in
let py = [|0.0; 0.0; 1.0; 1.0|] in
(* Create the color map with 128 colors and use plscmap1la to initialize
the color values with a linear varying transparency (or alpha) *)
plscmap1n 128;
plscmap1la true pos rcoord gcoord bcoord acoord (Some rev);
plgradient px py 90.0;
plend ();
()
|
