1 //
2 // Copyright 2013 Christian Henning
3 //
4 // Distributed under the Boost Software License, Version 1.0
5 // See accompanying file LICENSE_1_0.txt or copy at
6 // http://www.boost.org/LICENSE_1_0.txt
7 //
8 #ifndef BOOST_GIL_TEST_EXTENSION_IO_MANDEL_VIEW_HPP
9 #define BOOST_GIL_TEST_EXTENSION_IO_MANDEL_VIEW_HPP
10
11 #include <boost/gil.hpp>
12
13 #include <cmath>
14 #include <cstdint>
15
16 namespace gil = boost::gil;
17
18 // Models a Unary Function
19 template <typename P> // Models PixelValueConcept
20 struct mandelbrot_fn
21 {
22 using point_t = gil::point_t;
23 using const_t = mandelbrot_fn;
24 using value_type = P;
25 using reference = value_type;
26 using const_reference = value_type;
27 using argument_type = point_t;
28 using result_type = reference;
29 static constexpr bool is_mutable = false;
30
31 value_type in_color_;
32 value_type out_color_;
33 point_t img_size_;
34 static const int MAX_ITER = 100; // max number of iterations
35
36 mandelbrot_fn() = default;
mandelbrot_fnmandelbrot_fn37 mandelbrot_fn(gil::point_t const& sz, value_type const& in_color, value_type const& out_color)
38 : in_color_(in_color), out_color_(out_color), img_size_(sz)
39 {
40 }
41
widthmandelbrot_fn42 std::ptrdiff_t width()
43 {
44 return img_size_.x;
45 }
heightmandelbrot_fn46 std::ptrdiff_t height()
47 {
48 return img_size_.y;
49 }
50
operator ()mandelbrot_fn51 result_type operator()(gil::point_t const& p) const
52 {
53 // normalize the coords to (-2..1, -1.5..1.5)
54 // (actually make y -1.0..2 so it is asymmetric, so we can verify some view factory methods)
55 gil::point<double> const n{
56 static_cast<double>(p.x) / static_cast<double>(img_size_.x) * 3 - 2,
57 static_cast<double>(p.y) / static_cast<double>(img_size_.y) * 3 - 1.0f}; //1.5f}
58 double t = get_num_iter(n);
59 t = std::pow(t, 0.2);
60
61 value_type ret;
62 for (std::size_t k = 0; k < gil::num_channels<P>::value; ++k)
63 ret[k] =
64 (typename gil::channel_type<P>::type)(in_color_[k] * t + out_color_[k] * (1 - t));
65 return ret;
66 }
67
68 private:
get_num_itermandelbrot_fn69 double get_num_iter(boost::gil::point<double> const& p) const
70 {
71 gil::point<double> z(0, 0);
72 for (int i = 0; i < MAX_ITER; ++i)
73 {
74 z = gil::point<double>(z.x * z.x - z.y * z.y + p.x, 2 * z.x * z.y + p.y);
75 if (z.x * z.x + z.y * z.y > 4)
76 return i / (double)MAX_ITER;
77 }
78 return 0;
79 }
80 };
81
82 template <typename Pixel>
83 struct mandel_view
84 {
85 using deref_t = mandelbrot_fn<Pixel>;
86 using locator_t = gil::virtual_2d_locator<deref_t, false>;
87 using my_virt_view_t = gil::image_view<locator_t>;
88 using type = my_virt_view_t;
89 };
90
91 template <typename Pixel>
create_mandel_view(unsigned int width,unsigned int height,Pixel const & in,Pixel const & out)92 auto create_mandel_view(unsigned int width, unsigned int height, Pixel const& in, Pixel const& out)
93 -> typename mandel_view<Pixel>::type
94 {
95 using view_t = typename mandel_view<Pixel>::type;
96 using deref_t = typename mandel_view<Pixel>::deref_t;
97 using locator_t = typename mandel_view<Pixel>::locator_t;
98
99 gil::point_t dims(width, height);
100 return view_t(dims, locator_t(gil::point_t(0, 0), gil::point_t(1, 1), deref_t(dims, in, out)));
101 }
102
103 #endif // BOOST_GIL_TEST_EXTENSION_IO_MANDEL_VIEW_HPP
104