31{
36 typedef typename compositor_t::function function_t;
37
39 exprtk::rtl::io::print <T> print;
40
41 symbol_table_t symbol_table;
42
43 symbol_table.add_function("println", println);
44 symbol_table.add_function("print" , print );
45
46 symbol_table.
47 add_function("sleep",
48 [](T time_ms) -> T
49 {
50 std::this_thread::sleep_for(
51 std::chrono::milliseconds(static_cast<std::size_t>(time_ms)));
52 return T(1);
53 });
54
55 symbol_table.
56 add_function("clear",
57 [](T full) -> T
58 {
59 printf("%s\033[H", full == T(1) ? "" : "\033[2J");
60 std::fflush(stdout);
61 return T(1);
62 });
63
64 compositor_t compositor(symbol_table);
65
66 compositor.load_variables(true);
67 compositor.load_vectors (true);
68
69 compositor.add(
70 function_t("draw_chladni_contour")
71 .var("t")
72 .expression
73 (
74 " var min_x := -40; "
75 " var min_y := -30; "
76 " var max_x := +40; "
77 " var max_y := +30; "
78 " var x_incr := +1.0 / 1.7; "
79 " var y_incr := +1; "
80 " var a := 10.0 sin(t); "
81 " var b := 10.0 sin(t + 1.0); "
82 " var c := 0.9 sin(t); "
83 " "
84 " for (var y := min_y; y < max_y; y += y_incr) "
85 " { "
86 " for (var x := min_x; x < max_x; x += x_incr) "
87 " { "
88 " if (sin(x / 3 - a) + sin(y / 5 - b) <= c) "
89 " print('*'); "
90 " else "
91 " print(' '); "
92 " }; "
93 " "
94 " println(); "
95 " } "
96 " "
97 ));
98
99 const std::string chladni_contour_graphing_driver =
100 " var t := 0; "
101 " for (var frame := 0; frame < 1000; frame += 1) "
102 " { "
103 " t += 0.03; "
104 " "
105 " clear(frame % 100 == 0); "
106 " draw_chladni_contour(t); "
107 " sleep(40); "
108 " }; ";
109
110 expression_t expression;
111 expression.register_symbol_table(symbol_table);
112
113 parser_t parser;
114 parser.compile(chladni_contour_graphing_driver,expression);
115
116 expression.value();
117}
