1 #ifndef __DALI_MATH_UTILS_H__
2 #define __DALI_MATH_UTILS_H__
5 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
7 * Licensed under the Apache License, Version 2.0 (the "License");
8 * you may not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
11 * http://www.apache.org/licenses/LICENSE-2.0
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
22 #include <dali/public-api/common/dali-common.h>
23 #include <dali/public-api/common/constants.h>
29 * @brief Returns the next power of two.
31 * In case of numbers which are already a power of two this function returns the original number.
32 * If i is zero returns 1
33 * @param[in] i input number
34 * @return next power of two or i itself in case it's a power of two
36 inline unsigned int NextPowerOfTwo( unsigned int i )
38 DALI_ASSERT_DEBUG(i <= 1u << (sizeof(unsigned) * 8 - 1) && "Return type cannot represent the next power of two greater than the argument.");
55 * @brief Whether a number is power of two.
57 * @param[in] i input number
58 * @return true if i is power of two
60 inline bool IsPowerOfTwo( unsigned int i )
62 return (i != 0u) && ((i & (i - 1u)) == 0u);
66 * @brief Clamp a value.
68 * @param[in] value The value to clamp.
69 * @param[in] min The minimum allowed value.
70 * @param[in] max The maximum allowed value.
71 * @return T the clamped value
73 template< typename T >
74 inline const T& Clamp( const T& value, const T& min, const T& max )
76 const T& constrainedUpper = value < max ? value : max;
77 const T& constrainedUpperAndLower = constrainedUpper > min ? constrainedUpper : min;
78 return constrainedUpperAndLower;
82 * @brief Clamp a value directly.
84 * @param[in,out] value The value that will be clamped.
85 * @param[in] min The minimum allowed value.
86 * @param[in] max The maximum allowed value.
88 template< typename T >
89 inline void ClampInPlace( T& value, const T& min, const T& max )
91 const T& constrainedUpper = value < max ? value : max;
92 const T& constrainedUpperAndLower = constrainedUpper > min ? constrainedUpper : min;
93 value = constrainedUpperAndLower;
98 * @brief Linear interpolation between two values.
100 * @param[in] offset The offset through the range @p low to @p high.
101 * This value is clamped between 0 and 1
102 * @param[in] low Lowest value in range
103 * @param[in] high Highest value in range
104 * @return A value between low and high.
106 template< typename T >
107 inline const T Lerp( const float offset, const T& low, const T& high )
109 return low + ((high - low) * Clamp(offset, 0.0f, 1.0f));
113 * @brief Get an epsilon that is valid for the given range.
115 * @param[in] a the first value in the range
116 * @param[in] b the second value in the range.
117 * @return a suitable epsilon
119 inline float GetRangedEpsilon( float a, float b )
121 const float absA = fabsf( a );
122 const float absB = fabsf( b );
123 const float absF = absA > absB ? absA : absB;
124 const int absI = absF;
126 float epsilon = Math::MACHINE_EPSILON_10000;
129 return Math::MACHINE_EPSILON_0;
133 return Math::MACHINE_EPSILON_1;
137 return Math::MACHINE_EPSILON_10;
141 return Math::MACHINE_EPSILON_100;
143 else if (absI < 2000)
145 return Math::MACHINE_EPSILON_1000;
151 * @brief Helper function to compare equality of a floating point value with zero.
153 * @param[in] value the value to compare
154 * @return true if the value is equal to zero
156 #pragma GCC diagnostic push
157 #pragma GCC diagnostic ignored "-Wfloat-equal"
158 inline bool EqualsZero( float value )
160 return value == 0.0f;
162 #pragma GCC diagnostic pop
165 * @brief Helper function to compare equality of two floating point values.
167 * @param[in] a the first value to compare
168 * @param[in] b the second value to compare
169 * @return true if the values are equal within a minimal epsilon for their values
171 inline bool Equals( float a, float b )
173 return ( fabsf( a - b ) <= GetRangedEpsilon( a, b ) );
177 * @brief Helper function to compare equality of two floating point values.
179 * @param[in] a the first value to compare
180 * @param[in] b the second value to compare
181 * @param[in] epsilon the minimum epsilon value that will be used to consider the values different
182 * @return true if the difference between the values is less than the epsilon
184 inline bool Equals( float a, float b, float epsilon )
186 return ( fabsf( a - b ) <= epsilon );
190 * @brief Get an float that is rounded at specified place of decimals.
192 * @param[in] value float value
193 * @param[in] pos decimal place
194 * @return a rounded float
196 inline float Round(float value, int pos)
199 temp = value * powf( 10, pos );
200 temp = floorf( temp + 0.5 );
201 temp *= powf( 10, -pos );
206 * @brief Wrap x in domain (start) to (end).
208 * This works like a floating point version
209 * of the % modulo operation. But with an offset (start).
211 * For instance a domain is specified as:
216 * (\ / start) (\ / end)
219 * The value x will be confined to this domain.
220 * If x is below 2 e.g. 0, then it is wraped to 6.
221 * If x is above or equal to 8 e.g. 8.1 then it is
224 * Domain wrapping is useful for various problems from
225 * calculating positions in a space that repeats, to
226 * computing angles that range from 0 to 360.
228 * @param[in] x the point to be wrapped within the domain
229 * @param[in] start The start of the domain
230 * @param[in] end The end of the domain
232 * @note if start = end (i.e. size of domain 0), then wrapping will not occur
233 * and result will always be equal to start.
235 * @return the wrapped value over the domain (start) (end)
237 inline float WrapInDomain(float x, float start, float end)
239 float domain = end - start;
242 if(fabsf(domain) > Math::MACHINE_EPSILON_1)
244 return start + (x - floorf(x / domain) * domain);
252 * @brief Find the shortest distance (magnitude) and direction (sign)
253 * from (a) to (b) in domain (start) to (end).
255 * (\ / start) (\ / end)
258 * Knowing the shortest distance is useful with wrapped domains
259 * to solve problems such as determing the closest object to
260 * a given point, or determing whether turning left or turning
261 * right is the shortest route to get from angle 10 degrees
262 * to angle 350 degrees (clearly in a 0-360 degree domain, turning
263 * left 20 degrees is quicker than turning right 340 degrees).
265 * The value returned holds the distance and the direction from
266 * value a to value b. For instance in the above example it would
267 * return -20. i.e. subtract 20 from current value (10) to reach
268 * target wrapped value (350).
270 * @note assumes both (a) and (b) are already within the domain
273 * @param a the current value
274 * @param b the target value
275 * @param start the start of the domain
276 * @param end the end of the domain
277 * @return the shortest direction (the sign) and distance (the magnitude)
279 inline float ShortestDistanceInDomain( float a, float b, float start, float end )
282 float size = end-start;
287 // +ve vector, let's try perspective 1 domain to the right,
288 // and see if closer.
289 float aRight = a+size;
290 if( aRight-b < vect )
297 // -ve vector, let's try perspective 1 domain to the left,
298 // and see if closer.
299 float aLeft = a-size;
311 #endif // __DALI_MATH_UTILS_H__