1 /****************************************************************************
2 *
3 * fttrigon.h
4 *
5 * FreeType trigonometric functions (specification).
6 *
7 * Copyright (C) 2001-2023 by
8 * David Turner, Robert Wilhelm, and Werner Lemberg.
9 *
10 * This file is part of the FreeType project, and may only be used,
11 * modified, and distributed under the terms of the FreeType project
12 * license, LICENSE.TXT. By continuing to use, modify, or distribute
13 * this file you indicate that you have read the license and
14 * understand and accept it fully.
15 *
16 */
17
18
19 #ifndef FTTRIGON_H_
20 #define FTTRIGON_H_
21
22 #include <freetype/freetype.h>
23
24 #ifdef FREETYPE_H
25 #error "freetype.h of FreeType 1 has been loaded!"
26 #error "Please fix the directory search order for header files"
27 #error "so that freetype.h of FreeType 2 is found first."
28 #endif
29
30
31 FT_BEGIN_HEADER
32
33
34 /**************************************************************************
35 *
36 * @section:
37 * computations
38 *
39 */
40
41
42 /**************************************************************************
43 *
44 * @type:
45 * FT_Angle
46 *
47 * @description:
48 * This type is used to model angle values in FreeType. Note that the
49 * angle is a 16.16 fixed-point value expressed in degrees.
50 *
51 */
52 typedef FT_Fixed FT_Angle;
53
54
55 /**************************************************************************
56 *
57 * @macro:
58 * FT_ANGLE_PI
59 *
60 * @description:
61 * The angle pi expressed in @FT_Angle units.
62 *
63 */
64 #define FT_ANGLE_PI ( 180L << 16 )
65
66
67 /**************************************************************************
68 *
69 * @macro:
70 * FT_ANGLE_2PI
71 *
72 * @description:
73 * The angle 2*pi expressed in @FT_Angle units.
74 *
75 */
76 #define FT_ANGLE_2PI ( FT_ANGLE_PI * 2 )
77
78
79 /**************************************************************************
80 *
81 * @macro:
82 * FT_ANGLE_PI2
83 *
84 * @description:
85 * The angle pi/2 expressed in @FT_Angle units.
86 *
87 */
88 #define FT_ANGLE_PI2 ( FT_ANGLE_PI / 2 )
89
90
91 /**************************************************************************
92 *
93 * @macro:
94 * FT_ANGLE_PI4
95 *
96 * @description:
97 * The angle pi/4 expressed in @FT_Angle units.
98 *
99 */
100 #define FT_ANGLE_PI4 ( FT_ANGLE_PI / 4 )
101
102
103 /**************************************************************************
104 *
105 * @function:
106 * FT_Sin
107 *
108 * @description:
109 * Return the sinus of a given angle in fixed-point format.
110 *
111 * @input:
112 * angle ::
113 * The input angle.
114 *
115 * @return:
116 * The sinus value.
117 *
118 * @note:
119 * If you need both the sinus and cosinus for a given angle, use the
120 * function @FT_Vector_Unit.
121 *
122 */
123 FT_EXPORT( FT_Fixed )
124 FT_Sin( FT_Angle angle );
125
126
127 /**************************************************************************
128 *
129 * @function:
130 * FT_Cos
131 *
132 * @description:
133 * Return the cosinus of a given angle in fixed-point format.
134 *
135 * @input:
136 * angle ::
137 * The input angle.
138 *
139 * @return:
140 * The cosinus value.
141 *
142 * @note:
143 * If you need both the sinus and cosinus for a given angle, use the
144 * function @FT_Vector_Unit.
145 *
146 */
147 FT_EXPORT( FT_Fixed )
148 FT_Cos( FT_Angle angle );
149
150
151 /**************************************************************************
152 *
153 * @function:
154 * FT_Tan
155 *
156 * @description:
157 * Return the tangent of a given angle in fixed-point format.
158 *
159 * @input:
160 * angle ::
161 * The input angle.
162 *
163 * @return:
164 * The tangent value.
165 *
166 */
167 FT_EXPORT( FT_Fixed )
168 FT_Tan( FT_Angle angle );
169
170
171 /**************************************************************************
172 *
173 * @function:
174 * FT_Atan2
175 *
176 * @description:
177 * Return the arc-tangent corresponding to a given vector (x,y) in the 2d
178 * plane.
179 *
180 * @input:
181 * x ::
182 * The horizontal vector coordinate.
183 *
184 * y ::
185 * The vertical vector coordinate.
186 *
187 * @return:
188 * The arc-tangent value (i.e. angle).
189 *
190 */
191 FT_EXPORT( FT_Angle )
192 FT_Atan2( FT_Fixed x,
193 FT_Fixed y );
194
195
196 /**************************************************************************
197 *
198 * @function:
199 * FT_Angle_Diff
200 *
201 * @description:
202 * Return the difference between two angles. The result is always
203 * constrained to the ]-PI..PI] interval.
204 *
205 * @input:
206 * angle1 ::
207 * First angle.
208 *
209 * angle2 ::
210 * Second angle.
211 *
212 * @return:
213 * Constrained value of `angle2-angle1`.
214 *
215 */
216 FT_EXPORT( FT_Angle )
217 FT_Angle_Diff( FT_Angle angle1,
218 FT_Angle angle2 );
219
220
221 /**************************************************************************
222 *
223 * @function:
224 * FT_Vector_Unit
225 *
226 * @description:
227 * Return the unit vector corresponding to a given angle. After the
228 * call, the value of `vec.x` will be `cos(angle)`, and the value of
229 * `vec.y` will be `sin(angle)`.
230 *
231 * This function is useful to retrieve both the sinus and cosinus of a
232 * given angle quickly.
233 *
234 * @output:
235 * vec ::
236 * The address of target vector.
237 *
238 * @input:
239 * angle ::
240 * The input angle.
241 *
242 */
243 FT_EXPORT( void )
244 FT_Vector_Unit( FT_Vector* vec,
245 FT_Angle angle );
246
247
248 /**************************************************************************
249 *
250 * @function:
251 * FT_Vector_Rotate
252 *
253 * @description:
254 * Rotate a vector by a given angle.
255 *
256 * @inout:
257 * vec ::
258 * The address of target vector.
259 *
260 * @input:
261 * angle ::
262 * The input angle.
263 *
264 */
265 FT_EXPORT( void )
266 FT_Vector_Rotate( FT_Vector* vec,
267 FT_Angle angle );
268
269
270 /**************************************************************************
271 *
272 * @function:
273 * FT_Vector_Length
274 *
275 * @description:
276 * Return the length of a given vector.
277 *
278 * @input:
279 * vec ::
280 * The address of target vector.
281 *
282 * @return:
283 * The vector length, expressed in the same units that the original
284 * vector coordinates.
285 *
286 */
287 FT_EXPORT( FT_Fixed )
288 FT_Vector_Length( FT_Vector* vec );
289
290
291 /**************************************************************************
292 *
293 * @function:
294 * FT_Vector_Polarize
295 *
296 * @description:
297 * Compute both the length and angle of a given vector.
298 *
299 * @input:
300 * vec ::
301 * The address of source vector.
302 *
303 * @output:
304 * length ::
305 * The vector length.
306 *
307 * angle ::
308 * The vector angle.
309 *
310 */
311 FT_EXPORT( void )
312 FT_Vector_Polarize( FT_Vector* vec,
313 FT_Fixed *length,
314 FT_Angle *angle );
315
316
317 /**************************************************************************
318 *
319 * @function:
320 * FT_Vector_From_Polar
321 *
322 * @description:
323 * Compute vector coordinates from a length and angle.
324 *
325 * @output:
326 * vec ::
327 * The address of source vector.
328 *
329 * @input:
330 * length ::
331 * The vector length.
332 *
333 * angle ::
334 * The vector angle.
335 *
336 */
337 FT_EXPORT( void )
338 FT_Vector_From_Polar( FT_Vector* vec,
339 FT_Fixed length,
340 FT_Angle angle );
341
342 /* */
343
344
345 FT_END_HEADER
346
347 #endif /* FTTRIGON_H_ */
348
349
350 /* END */