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 <algorithm> // std::min & max
25 #include <dali/public-api/common/dali-common.h>
26 #include <dali/public-api/common/constants.h>
32 * @brief Returns the next power of two.
34 * In case of numbers which are already a power of two this function returns the original number.
35 * If i is zero returns 1
36 * @param[in] i input number
37 * @return next power of two or i itself in case it's a power of two
39 inline unsigned int NextPowerOfTwo( unsigned int i )
41 DALI_ASSERT_DEBUG(i <= 1U << (sizeof(unsigned) * 8 - 1) && "Return type cannot represent the next power of two greater than the argument.");
58 * @brief Whether a number is power of two.
60 * @param[in] i input number
61 * @return true if i is power of two
63 inline bool IsPowerOfTwo( unsigned int i )
65 return (i != 0) && ((i & (i - 1)) == 0);
69 * @brief Clamp a value.
71 * @param[in] value The value to clamp.
72 * @param[in] min The minimum allowed value.
73 * @param[in] max The maximum allowed value.
74 * @return T the clamped value
76 template< typename T >
77 inline const T& Clamp( const T& value, const T& min, const T& max )
79 return std::max( std::min( value, max ), min );
83 * @brief Clamp a value directly.
85 * @param[in,out] value The value that will be clamped.
86 * @param[in] min The minimum allowed value.
87 * @param[in] max The maximum allowed value.
89 template< typename T >
90 inline void ClampInPlace( T& value, const T& min, const T& max )
92 value = std::max( std::min( value, max ), min );
97 * @brief Linear interpolation between two values.
99 * @param[in] offset The offset through the range @p low to @p high.
100 * This value is clamped between 0 and 1
101 * @param[in] low Lowest value in range
102 * @param[in] high Highest value in range
103 * @return A value between low and high.
105 template< typename T >
106 inline const T Lerp( const float offset, const T& low, const T& high )
108 return low + ((high - low) * Clamp(offset, 0.0f, 1.0f));
112 * @brief Get an epsilon that is valid for the given range.
114 * @param[in] a the first value in the range
115 * @param[in] b the second value in the range.
116 * @return a suitable epsilon
118 inline float GetRangedEpsilon(float a, float b)
120 float abs_f = std::max(fabsf(a), fabsf(b));
121 int abs_i = (int) abs_f;
123 float epsilon = Math::MACHINE_EPSILON_10000;
126 return Math::MACHINE_EPSILON_0;
130 return Math::MACHINE_EPSILON_1;
134 return Math::MACHINE_EPSILON_10;
136 else if (abs_i < 200)
138 return Math::MACHINE_EPSILON_100;
140 else if (abs_i < 2000)
142 return Math::MACHINE_EPSILON_1000;
148 * @brief Helper function to compare equality of a floating point value with zero.
150 * @param[in] value the value to compare
151 * @return true if the value is equal to zero
153 #pragma GCC diagnostic push
154 #pragma GCC diagnostic ignored "-Wfloat-equal"
155 inline bool EqualsZero( float value )
157 return value == 0.0f;
159 #pragma GCC diagnostic pop
162 * @brief Helper function to compare equality of two floating point values.
164 * @param[in] a the first value to compare
165 * @param[in] b the second value to compare
166 * @return true if the values are equal within a minimal epsilon for their values
168 inline bool Equals( float a, float b )
170 return ( fabsf( a - b ) <= GetRangedEpsilon( a, b ) );
174 * @brief Helper function to compare equality of two floating point values.
176 * @param[in] a the first value to compare
177 * @param[in] b the second value to compare
178 * @param[in] epsilon the minimum epsilon value that will be used to consider the values different
179 * @return true if the difference between the values is less than the epsilon
181 inline bool Equals( float a, float b, float epsilon )
183 return ( fabsf( a - b ) <= epsilon );
187 * @brief Get an float that is rounded at specified place of decimals.
189 * @param[in] value float value
190 * @param[in] pos decimal place
191 * @return a rounded float
193 inline float Round(float value, int pos)
196 temp = value * powf( 10, pos );
197 temp = floorf( temp + 0.5 );
198 temp *= powf( 10, -pos );
203 * @brief Wrap x in domain (start) to (end).
205 * This works like a floating point version
206 * of the % modulo operation. But with an offset (start).
208 * For instance a domain is specified as:
213 * (\ / start) (\ / end)
216 * The value x will be confined to this domain.
217 * If x is below 2 e.g. 0, then it is wraped to 6.
218 * If x is above or equal to 8 e.g. 8.1 then it is
221 * Domain wrapping is useful for various problems from
222 * calculating positions in a space that repeats, to
223 * computing angles that range from 0 to 360.
225 * @param[in] x the point to be wrapped within the domain
226 * @param[in] start The start of the domain
227 * @param[in] end The end of the domain
229 * @note if start = end (i.e. size of domain 0), then wrapping will not occur
230 * and result will always be equal to start.
232 * @return the wrapped value over the domain (start) (end)
234 inline float WrapInDomain(float x, float start, float end)
236 float domain = end - start;
239 if(fabsf(domain) > Math::MACHINE_EPSILON_1)
241 return start + (x - floorf(x / domain) * domain);
249 * @brief Find the shortest distance (magnitude) and direction (sign)
250 * from (a) to (b) in domain (start) to (end).
252 * (\ / start) (\ / end)
255 * Knowing the shortest distance is useful with wrapped domains
256 * to solve problems such as determing the closest object to
257 * a given point, or determing whether turning left or turning
258 * right is the shortest route to get from angle 10 degrees
259 * to angle 350 degrees (clearly in a 0-360 degree domain, turning
260 * left 20 degrees is quicker than turning right 340 degrees).
262 * The value returned holds the distance and the direction from
263 * value a to value b. For instance in the above example it would
264 * return -20. i.e. subtract 20 from current value (10) to reach
265 * target wrapped value (350).
267 * @note assumes both (a) and (b) are already within the domain
270 * @param a the current value
271 * @param b the target value
272 * @param start the start of the domain
273 * @param end the end of the domain
274 * @return the shortest direction (the sign) and distance (the magnitude)
276 inline float ShortestDistanceInDomain( float a, float b, float start, float end )
279 float size = end-start;
284 // +ve vector, let's try perspective 1 domain to the right,
285 // and see if closer.
286 float aRight = a+size;
287 if( aRight-b < vect )
294 // -ve vector, let's try perspective 1 domain to the left,
295 // and see if closer.
296 float aLeft = a-size;
308 #endif // __DALI_MATH_UTILS_H__