1 /*
2  * Copyright 2013 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef TNT_MATH_VEC2_H
18 #define TNT_MATH_VEC2_H
19 
20 #include "TVecHelpers.h"
21 
22 #include <type_traits>
23 
24 #include <assert.h>
25 #include <stdint.h>
26 #include <sys/types.h>
27 
28 namespace filament {
29 namespace math {
30 // -------------------------------------------------------------------------------------
31 
32 namespace details {
33 
34 template<typename T>
35 class MATH_EMPTY_BASES TVec2 :
36         public TVecProductOperators<TVec2, T>,
37         public TVecAddOperators<TVec2, T>,
38         public TVecUnaryOperators<TVec2, T>,
39         public TVecComparisonOperators<TVec2, T>,
40         public TVecFunctions<TVec2, T> {
41 public:
42     typedef T value_type;
43     typedef T& reference;
44     typedef T const& const_reference;
45     typedef size_t size_type;
46     static constexpr size_t SIZE = 2;
47 
48     union {
49         T v[SIZE] MATH_CONSTEXPR_INIT;
50         struct { T x, y; };
51         struct { T s, t; };
52         struct { T r, g; };
53     };
54 
size()55     inline constexpr size_type size() const { return SIZE; }
56 
57     // array access
58     inline constexpr T const& operator[](size_t i) const noexcept {
59         assert(i < SIZE);
60         return v[i];
61     }
62 
63     inline constexpr T& operator[](size_t i) noexcept {
64         assert(i < SIZE);
65         return v[i];
66     }
67 
68     // constructors
69 
70     // default constructor
TVec2()71     MATH_DEFAULT_CTOR_CONSTEXPR TVec2() MATH_DEFAULT_CTOR
72 
73     // handles implicit conversion to a tvec4. must not be explicit.
74     template<typename A, typename = enable_if_arithmetic_t<A>>
75     constexpr TVec2(A v) noexcept : v{ T(v), T(v) } {}
76 
77     template<typename A, typename B, typename = enable_if_arithmetic_t<A, B>>
TVec2(A x,B y)78     constexpr TVec2(A x, B y) noexcept : v{ T(x), T(y) } {}
79 
80     template<typename A, typename = enable_if_arithmetic_t<A>>
TVec2(const TVec2<A> & v)81     constexpr TVec2(const TVec2<A>& v) noexcept : v{ T(v[0]), T(v[1]) } {}
82 
83     // cross product works only on vectors of size 2 or 3
84     template<typename U>
85     friend inline constexpr
cross(const TVec2 & u,const TVec2<U> & v)86     arithmetic_result_t<T, U> cross(const TVec2& u, const TVec2<U>& v) noexcept {
87         return u[0] * v[1] - u[1] * v[0];
88     }
89 };
90 
91 }  // namespace details
92 
93 // ----------------------------------------------------------------------------------------
94 
95 template<typename T, typename = details::enable_if_arithmetic_t<T>>
96 using vec2 = details::TVec2<T>;
97 
98 using float2 = vec2<float>;
99 
100 // ----------------------------------------------------------------------------------------
101 }  // namespace math
102 }  // namespace filament
103 
104 #endif  // TNT_MATH_VEC2_H
105