1 #ifndef __DALI_MATH_UTILS_H__
2 #define __DALI_MATH_UTILS_H__
5 * Copyright (c) 2015 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>
28 * @addtogroup dali_core_math
33 * @brief Returns the next power of two.
35 * In case of numbers which are already a power of two this function returns the original number.
36 * If i is zero returns 1.
38 * @param[in] i Input number
39 * @return The next power of two or i itself in case it's a power of two
41 inline unsigned int NextPowerOfTwo( unsigned int i )
43 DALI_ASSERT_ALWAYS(i <= 1u << (sizeof(unsigned) * 8 - 1) && "Return type cannot represent the next power of two greater than the argument.");
60 * @brief Whether a number is power of two.
63 * @param[in] i Input number
64 * @return True if i is power of two.
66 inline bool IsPowerOfTwo( unsigned int i )
68 return (i != 0u) && ((i & (i - 1u)) == 0u);
72 * @brief Clamp a value.
75 * @param[in] value The value to clamp.
76 * @param[in] min The minimum allowed value.
77 * @param[in] max The maximum allowed value.
78 * @return T the clamped value
80 template< typename T >
81 inline const T& Clamp( const T& value, const T& min, const T& max )
83 const T& constrainedUpper = value < max ? value : max;
84 const T& constrainedUpperAndLower = constrainedUpper > min ? constrainedUpper : min;
85 return constrainedUpperAndLower;
89 * @brief Clamp a value directly.
92 * @param[in,out] value The value that will be clamped.
93 * @param[in] min The minimum allowed value.
94 * @param[in] max The maximum allowed value.
96 template< typename T >
97 inline void ClampInPlace( T& value, const T& min, const T& max )
99 const T& constrainedUpper = value < max ? value : max;
100 const T& constrainedUpperAndLower = constrainedUpper > min ? constrainedUpper : min;
101 value = constrainedUpperAndLower;
106 * @brief Linear interpolation between two values.
109 * @param[in] offset The offset through the range @p low to @p high.
110 * This value is clamped between 0 and 1.
111 * @param[in] low Lowest value in range
112 * @param[in] high Highest value in range
113 * @return A value between low and high.
115 template< typename T >
116 inline const T Lerp( const float offset, const T& low, const T& high )
118 return low + ((high - low) * Clamp(offset, 0.0f, 1.0f));
122 * @brief Get an epsilon that is valid for the given range.
125 * @param[in] a the first value in the range
126 * @param[in] b the second value in the range.
127 * @return a suitable epsilon
129 inline float GetRangedEpsilon( float a, float b )
131 const float absA = fabsf( a );
132 const float absB = fabsf( b );
133 const float absF = absA > absB ? absA : absB;
134 const int absI = absF;
136 float epsilon = Math::MACHINE_EPSILON_10000;
139 return Math::MACHINE_EPSILON_0;
143 return Math::MACHINE_EPSILON_1;
147 return Math::MACHINE_EPSILON_10;
151 return Math::MACHINE_EPSILON_100;
153 else if (absI < 2000)
155 return Math::MACHINE_EPSILON_1000;
161 * @brief Helper function to compare equality of a floating point value with zero.
164 * @param[in] value the value to compare
165 * @return true if the value is equal to zero
167 #pragma GCC diagnostic push
168 #pragma GCC diagnostic ignored "-Wfloat-equal"
169 inline bool EqualsZero( float value )
171 return value == 0.0f;
173 #pragma GCC diagnostic pop
176 * @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 * @return true if the values are equal within a minimal epsilon for their values
183 inline bool Equals( float a, float b )
185 return ( fabsf( a - b ) <= GetRangedEpsilon( a, b ) );
189 * @brief Helper function to compare equality of two floating point values.
192 * @param[in] a the first value to compare
193 * @param[in] b the second value to compare
194 * @param[in] epsilon the minimum epsilon value that will be used to consider the values different
195 * @return true if the difference between the values is less than the epsilon
197 inline bool Equals( float a, float b, float epsilon )
199 return ( fabsf( a - b ) <= epsilon );
203 * @brief Get an float that is rounded at specified place of decimals.
206 * @param[in] value float value
207 * @param[in] pos decimal place
208 * @return a rounded float
210 inline float Round(float value, int pos)
213 temp = value * powf( 10, pos );
214 temp = floorf( temp + 0.5 );
215 temp *= powf( 10, -pos );
220 * @brief Wrap x in domain (start) to (end).
222 * This works like a floating point version
223 * of the % modulo operation. But with an offset (start).
225 * For instance a domain is specified as:
231 * (\ / start) (\ / end)
235 * The value x will be confined to this domain.
236 * If x is below 2 e.g. 0, then it is wrapped to 6.
237 * If x is above or equal to 8 e.g. 8.1 then it is
240 * Domain wrapping is useful for various problems from
241 * calculating positions in a space that repeats, to
242 * computing angles that range from 0 to 360.
245 * @param[in] x the point to be wrapped within the domain
246 * @param[in] start The start of the domain
247 * @param[in] end The end of the domain
249 * @return the wrapped value over the domain (start) (end)
250 * @note If start = end (i.e. size of domain 0), then wrapping will not occur
251 * and result will always be equal to start.
254 inline float WrapInDomain(float x, float start, float end)
256 float domain = end - start;
259 if(fabsf(domain) > Math::MACHINE_EPSILON_1)
261 return start + (x - floorf(x / domain) * domain);
269 * @brief Find the shortest distance (magnitude) and direction (sign)
270 * from (a) to (b) in domain (start) to (end).
273 * (\ / start) (\ / end)
277 * Knowing the shortest distance is useful with wrapped domains
278 * to solve problems such as determining the closest object to
279 * a given point, or determining whether turning left or turning
280 * right is the shortest route to get from angle 10 degrees
281 * to angle 350 degrees (clearly in a 0-360 degree domain, turning
282 * left 20 degrees is quicker than turning right 340 degrees).
284 * The value returned holds the distance and the direction from
285 * value a to value b. For instance in the above example it would
286 * return -20. i.e. subtract 20 from current value (10) to reach
287 * target wrapped value (350).
290 * @param a the current value
291 * @param b the target value
292 * @param start the start of the domain
293 * @param end the end of the domain
294 * @return the shortest direction (the sign) and distance (the magnitude)
295 * @note Assumes both (a) and (b) are already within the domain
299 inline float ShortestDistanceInDomain( float a, float b, float start, float end )
302 float size = end-start;
307 // +ve vector, let's try perspective 1 domain to the right,
308 // and see if closer.
309 float aRight = a+size;
310 if( aRight-b < vect )
317 // -ve vector, let's try perspective 1 domain to the left,
318 // and see if closer.
319 float aLeft = a-size;
330 * @brief Extracts the sign of a number
333 * @param[in] value The value we want to extract the sign
334 * @return -1 for negative values, +1 for positive values and 0 if value is 0
336 template <typename T>
339 return ( T(0) < value ) - ( value < T(0) );
347 #endif // __DALI_MATH_UTILS_H__