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fttrigon.h (7411B)

---

/****************************************************************************
*
* fttrigon.h
*
*   FreeType trigonometric functions (specification).
*
* Copyright (C) 2001-2025 by
* David Turner, Robert Wilhelm, and Werner Lemberg.
*
* This file is part of the FreeType project, and may only be used,
* modified, and distributed under the terms of the FreeType project
* license, LICENSE.TXT.  By continuing to use, modify, or distribute
* this file you indicate that you have read the license and
* understand and accept it fully.
*
*/


#ifndef FTTRIGON_H_
#define FTTRIGON_H_

#include <freetype/freetype.h>

#ifdef FREETYPE_H
#error "freetype.h of FreeType 1 has been loaded!"
#error "Please fix the directory search order for header files"
#error "so that freetype.h of FreeType 2 is found first."
#endif


FT_BEGIN_HEADER


 /**************************************************************************
  *
  * @section:
  *  computations
  *
  */


 /**************************************************************************
  *
  * @type:
  *   FT_Angle
  *
  * @description:
  *   This type is used to model angle values in FreeType.  Note that the
  *   angle is a 16.16 fixed-point value expressed in degrees.
  *
  */
 typedef FT_Fixed  FT_Angle;


 /**************************************************************************
  *
  * @macro:
  *   FT_ANGLE_PI
  *
  * @description:
  *   The angle pi expressed in @FT_Angle units.
  *
  */
#define FT_ANGLE_PI  ( 180L << 16 )


 /**************************************************************************
  *
  * @macro:
  *   FT_ANGLE_2PI
  *
  * @description:
  *   The angle 2*pi expressed in @FT_Angle units.
  *
  */
#define FT_ANGLE_2PI  ( FT_ANGLE_PI * 2 )


 /**************************************************************************
  *
  * @macro:
  *   FT_ANGLE_PI2
  *
  * @description:
  *   The angle pi/2 expressed in @FT_Angle units.
  *
  */
#define FT_ANGLE_PI2  ( FT_ANGLE_PI / 2 )


 /**************************************************************************
  *
  * @macro:
  *   FT_ANGLE_PI4
  *
  * @description:
  *   The angle pi/4 expressed in @FT_Angle units.
  *
  */
#define FT_ANGLE_PI4  ( FT_ANGLE_PI / 4 )


 /**************************************************************************
  *
  * @function:
  *   FT_Sin
  *
  * @description:
  *   Return the sinus of a given angle in fixed-point format.
  *
  * @input:
  *   angle ::
  *     The input angle.
  *
  * @return:
  *   The sinus value.
  *
  * @note:
  *   If you need both the sinus and cosinus for a given angle, use the
  *   function @FT_Vector_Unit.
  *
  */
 FT_EXPORT( FT_Fixed )
 FT_Sin( FT_Angle  angle );


 /**************************************************************************
  *
  * @function:
  *   FT_Cos
  *
  * @description:
  *   Return the cosinus of a given angle in fixed-point format.
  *
  * @input:
  *   angle ::
  *     The input angle.
  *
  * @return:
  *   The cosinus value.
  *
  * @note:
  *   If you need both the sinus and cosinus for a given angle, use the
  *   function @FT_Vector_Unit.
  *
  */
 FT_EXPORT( FT_Fixed )
 FT_Cos( FT_Angle  angle );


 /**************************************************************************
  *
  * @function:
  *   FT_Tan
  *
  * @description:
  *   Return the tangent of a given angle in fixed-point format.
  *
  * @input:
  *   angle ::
  *     The input angle.
  *
  * @return:
  *   The tangent value.
  *
  */
 FT_EXPORT( FT_Fixed )
 FT_Tan( FT_Angle  angle );


 /**************************************************************************
  *
  * @function:
  *   FT_Atan2
  *
  * @description:
  *   Return the arc-tangent corresponding to a given vector (x,y) in the 2d
  *   plane.
  *
  * @input:
  *   x ::
  *     The horizontal vector coordinate.
  *
  *   y ::
  *     The vertical vector coordinate.
  *
  * @return:
  *   The arc-tangent value (i.e. angle).
  *
  */
 FT_EXPORT( FT_Angle )
 FT_Atan2( FT_Fixed  x,
           FT_Fixed  y );


 /**************************************************************************
  *
  * @function:
  *   FT_Angle_Diff
  *
  * @description:
  *   Return the difference between two angles.  The result is always
  *   constrained to the ]-PI..PI] interval.
  *
  * @input:
  *   angle1 ::
  *     First angle.
  *
  *   angle2 ::
  *     Second angle.
  *
  * @return:
  *   Constrained value of `angle2-angle1`.
  *
  */
 FT_EXPORT( FT_Angle )
 FT_Angle_Diff( FT_Angle  angle1,
                FT_Angle  angle2 );


 /**************************************************************************
  *
  * @function:
  *   FT_Vector_Unit
  *
  * @description:
  *   Return the unit vector corresponding to a given angle.  After the
  *   call, the value of `vec.x` will be `cos(angle)`, and the value of
  *   `vec.y` will be `sin(angle)`.
  *
  *   This function is useful to retrieve both the sinus and cosinus of a
  *   given angle quickly.
  *
  * @output:
  *   vec ::
  *     The address of target vector.
  *
  * @input:
  *   angle ::
  *     The input angle.
  *
  */
 FT_EXPORT( void )
 FT_Vector_Unit( FT_Vector*  vec,
                 FT_Angle    angle );


 /**************************************************************************
  *
  * @function:
  *   FT_Vector_Rotate
  *
  * @description:
  *   Rotate a vector by a given angle.
  *
  * @inout:
  *   vec ::
  *     The address of target vector.
  *
  * @input:
  *   angle ::
  *     The input angle.
  *
  */
 FT_EXPORT( void )
 FT_Vector_Rotate( FT_Vector*  vec,
                   FT_Angle    angle );


 /**************************************************************************
  *
  * @function:
  *   FT_Vector_Length
  *
  * @description:
  *   Return the length of a given vector.
  *
  * @input:
  *   vec ::
  *     The address of target vector.
  *
  * @return:
  *   The vector length, expressed in the same units that the original
  *   vector coordinates.
  *
  */
 FT_EXPORT( FT_Fixed )
 FT_Vector_Length( FT_Vector*  vec );


 /**************************************************************************
  *
  * @function:
  *   FT_Vector_Polarize
  *
  * @description:
  *   Compute both the length and angle of a given vector.
  *
  * @input:
  *   vec ::
  *     The address of source vector.
  *
  * @output:
  *   length ::
  *     The vector length.
  *
  *   angle ::
  *     The vector angle.
  *
  */
 FT_EXPORT( void )
 FT_Vector_Polarize( FT_Vector*  vec,
                     FT_Fixed   *length,
                     FT_Angle   *angle );


 /**************************************************************************
  *
  * @function:
  *   FT_Vector_From_Polar
  *
  * @description:
  *   Compute vector coordinates from a length and angle.
  *
  * @output:
  *   vec ::
  *     The address of source vector.
  *
  * @input:
  *   length ::
  *     The vector length.
  *
  *   angle ::
  *     The vector angle.
  *
  */
 FT_EXPORT( void )
 FT_Vector_From_Polar( FT_Vector*  vec,
                       FT_Fixed    length,
                       FT_Angle    angle );

 /* */


FT_END_HEADER

#endif /* FTTRIGON_H_ */


/* END */