1/*
2 * Copyright (C) 2014 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#ifndef MATHUTILS_H
17#define MATHUTILS_H
18
19namespace android {
20namespace uirenderer {
21
22#define NON_ZERO_EPSILON (0.001f)
23#define ALPHA_EPSILON (0.001f)
24
25class MathUtils {
26public:
27    /**
28     * Check for floats that are close enough to zero.
29     */
30    inline static bool isZero(float value) {
31        return (value >= -NON_ZERO_EPSILON) && (value <= NON_ZERO_EPSILON);
32    }
33
34    inline static bool isPositive(float value) {
35        return value >= NON_ZERO_EPSILON;
36    }
37
38    /**
39     * Clamps alpha value, and snaps when very near 0 or 1
40     */
41    inline static float clampAlpha(float alpha) {
42        if (alpha <= ALPHA_EPSILON) {
43            return 0;
44        } else if (alpha >= (1 - ALPHA_EPSILON)) {
45            return 1;
46        } else {
47            return alpha;
48        }
49    }
50
51    /*
52     * Clamps positive tessellation scale values
53     */
54    inline static float clampTessellationScale(float scale) {
55        const float MIN_SCALE = 0.0001;
56        const float MAX_SCALE = 1e10;
57        if (scale < MIN_SCALE) {
58            return MIN_SCALE;
59        } else if (scale > MAX_SCALE) {
60            return MAX_SCALE;
61        }
62        return scale;
63    }
64
65    inline static bool areEqual(float valueA, float valueB) {
66        return isZero(valueA - valueB);
67    }
68
69    template<typename T>
70    static inline T max(T a, T b) {
71        return a > b ? a : b;
72    }
73
74    template<typename T>
75    static inline T min(T a, T b) {
76        return a < b ? a : b;
77    }
78
79    template<typename T>
80    static inline T clamp(T a, T minValue, T maxValue) {
81        return min(max(a, minValue), maxValue);
82    }
83
84    inline static float lerp(float v1, float v2, float t) {
85        return v1 + ((v2 - v1) * t);
86    }
87}; // class MathUtils
88
89} /* namespace uirenderer */
90} /* namespace android */
91
92#endif /* MATHUTILS_H */
93