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
37 * @param[in] i input number
38 * @return next power of two or i itself in case it's a power of two
40 inline unsigned int NextPowerOfTwo( unsigned int i )
42 DALI_ASSERT_ALWAYS(i <= 1u << (sizeof(unsigned) * 8 - 1) && "Return type cannot represent the next power of two greater than the argument.");
59 * @brief Whether a number is power of two.
61 * @param[in] i input number
62 * @return true if i is power of two
64 inline bool IsPowerOfTwo( unsigned int i )
66 return (i != 0u) && ((i & (i - 1u)) == 0u);
70 * @brief Clamp a value.
72 * @param[in] value The value to clamp.
73 * @param[in] min The minimum allowed value.
74 * @param[in] max The maximum allowed value.
75 * @return T the clamped value
77 template< typename T >
78 inline const T& Clamp( const T& value, const T& min, const T& max )
80 const T& constrainedUpper = value < max ? value : max;
81 const T& constrainedUpperAndLower = constrainedUpper > min ? constrainedUpper : min;
82 return constrainedUpperAndLower;
86 * @brief Clamp a value directly.
88 * @param[in,out] value The value that will be clamped.
89 * @param[in] min The minimum allowed value.
90 * @param[in] max The maximum allowed value.
92 template< typename T >
93 inline void ClampInPlace( T& value, const T& min, const T& max )
95 const T& constrainedUpper = value < max ? value : max;
96 const T& constrainedUpperAndLower = constrainedUpper > min ? constrainedUpper : min;
97 value = constrainedUpperAndLower;
102 * @brief Linear interpolation between two values.
104 * @param[in] offset The offset through the range @p low to @p high.
105 * This value is clamped between 0 and 1
106 * @param[in] low Lowest value in range
107 * @param[in] high Highest value in range
108 * @return A value between low and high.
110 template< typename T >
111 inline const T Lerp( const float offset, const T& low, const T& high )
113 return low + ((high - low) * Clamp(offset, 0.0f, 1.0f));
117 * @brief Get an epsilon that is valid for the given range.
119 * @param[in] a the first value in the range
120 * @param[in] b the second value in the range.
121 * @return a suitable epsilon
123 inline float GetRangedEpsilon( float a, float b )
125 const float absA = fabsf( a );
126 const float absB = fabsf( b );
127 const float absF = absA > absB ? absA : absB;
128 const int absI = absF;
130 float epsilon = Math::MACHINE_EPSILON_10000;
133 return Math::MACHINE_EPSILON_0;
137 return Math::MACHINE_EPSILON_1;
141 return Math::MACHINE_EPSILON_10;
145 return Math::MACHINE_EPSILON_100;
147 else if (absI < 2000)
149 return Math::MACHINE_EPSILON_1000;
155 * @brief Helper function to compare equality of a floating point value with zero.
157 * @param[in] value the value to compare
158 * @return true if the value is equal to zero
160 #pragma GCC diagnostic push
161 #pragma GCC diagnostic ignored "-Wfloat-equal"
162 inline bool EqualsZero( float value )
164 return value == 0.0f;
166 #pragma GCC diagnostic pop
169 * @brief Helper function to compare equality of two floating point values.
171 * @param[in] a the first value to compare
172 * @param[in] b the second value to compare
173 * @return true if the values are equal within a minimal epsilon for their values
175 inline bool Equals( float a, float b )
177 return ( fabsf( a - b ) <= GetRangedEpsilon( a, b ) );
181 * @brief Helper function to compare equality of two floating point values.
183 * @param[in] a the first value to compare
184 * @param[in] b the second value to compare
185 * @param[in] epsilon the minimum epsilon value that will be used to consider the values different
186 * @return true if the difference between the values is less than the epsilon
188 inline bool Equals( float a, float b, float epsilon )
190 return ( fabsf( a - b ) <= epsilon );
194 * @brief Get an float that is rounded at specified place of decimals.
196 * @param[in] value float value
197 * @param[in] pos decimal place
198 * @return a rounded float
200 inline float Round(float value, int pos)
203 temp = value * powf( 10, pos );
204 temp = floorf( temp + 0.5 );
205 temp *= powf( 10, -pos );
210 * @brief Wrap x in domain (start) to (end).
212 * This works like a floating point version
213 * of the % modulo operation. But with an offset (start).
215 * For instance a domain is specified as:
220 * (\ / start) (\ / end)
223 * The value x will be confined to this domain.
224 * If x is below 2 e.g. 0, then it is wraped to 6.
225 * If x is above or equal to 8 e.g. 8.1 then it is
228 * Domain wrapping is useful for various problems from
229 * calculating positions in a space that repeats, to
230 * computing angles that range from 0 to 360.
232 * @param[in] x the point to be wrapped within the domain
233 * @param[in] start The start of the domain
234 * @param[in] end The end of the domain
236 * @note if start = end (i.e. size of domain 0), then wrapping will not occur
237 * and result will always be equal to start.
239 * @return the wrapped value over the domain (start) (end)
241 inline float WrapInDomain(float x, float start, float end)
243 float domain = end - start;
246 if(fabsf(domain) > Math::MACHINE_EPSILON_1)
248 return start + (x - floorf(x / domain) * domain);
256 * @brief Find the shortest distance (magnitude) and direction (sign)
257 * from (a) to (b) in domain (start) to (end).
259 * (\ / start) (\ / end)
262 * Knowing the shortest distance is useful with wrapped domains
263 * to solve problems such as determing the closest object to
264 * a given point, or determing whether turning left or turning
265 * right is the shortest route to get from angle 10 degrees
266 * to angle 350 degrees (clearly in a 0-360 degree domain, turning
267 * left 20 degrees is quicker than turning right 340 degrees).
269 * The value returned holds the distance and the direction from
270 * value a to value b. For instance in the above example it would
271 * return -20. i.e. subtract 20 from current value (10) to reach
272 * target wrapped value (350).
274 * @note assumes both (a) and (b) are already within the domain
277 * @param a the current value
278 * @param b the target value
279 * @param start the start of the domain
280 * @param end the end of the domain
281 * @return the shortest direction (the sign) and distance (the magnitude)
283 inline float ShortestDistanceInDomain( float a, float b, float start, float end )
286 float size = end-start;
291 // +ve vector, let's try perspective 1 domain to the right,
292 // and see if closer.
293 float aRight = a+size;
294 if( aRight-b < vect )
301 // -ve vector, let's try perspective 1 domain to the left,
302 // and see if closer.
303 float aLeft = a-size;
318 #endif // __DALI_MATH_UTILS_H__