351 lines
7.2 KiB
C
351 lines
7.2 KiB
C
/****************************************************************************
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*
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* fttrigon.h
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*
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* FreeType trigonometric functions (specification).
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*
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* Copyright 2001-2018 by
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* David Turner, Robert Wilhelm, and Werner Lemberg.
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*
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* This file is part of the FreeType project, and may only be used,
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* modified, and distributed under the terms of the FreeType project
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* license, LICENSE.TXT. By continuing to use, modify, or distribute
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* this file you indicate that you have read the license and
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* understand and accept it fully.
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*
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*/
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#ifndef FTTRIGON_H_
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#define FTTRIGON_H_
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#include FT_FREETYPE_H
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#ifdef FREETYPE_H
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#error "freetype.h of FreeType 1 has been loaded!"
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#error "Please fix the directory search order for header files"
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#error "so that freetype.h of FreeType 2 is found first."
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#endif
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FT_BEGIN_HEADER
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/**************************************************************************
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*
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* @section:
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* computations
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*
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*/
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/**************************************************************************
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*
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* @type:
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* FT_Angle
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*
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* @description:
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* This type is used to model angle values in FreeType. Note that the
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* angle is a 16.16 fixed-point value expressed in degrees.
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*
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*/
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typedef FT_Fixed FT_Angle;
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/**************************************************************************
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*
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* @macro:
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* FT_ANGLE_PI
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*
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* @description:
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* The angle pi expressed in @FT_Angle units.
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*
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*/
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#define FT_ANGLE_PI ( 180L << 16 )
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/**************************************************************************
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*
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* @macro:
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* FT_ANGLE_2PI
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*
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* @description:
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* The angle 2*pi expressed in @FT_Angle units.
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*
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*/
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#define FT_ANGLE_2PI ( FT_ANGLE_PI * 2 )
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/**************************************************************************
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*
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* @macro:
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* FT_ANGLE_PI2
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*
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* @description:
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* The angle pi/2 expressed in @FT_Angle units.
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*
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*/
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#define FT_ANGLE_PI2 ( FT_ANGLE_PI / 2 )
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/**************************************************************************
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*
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* @macro:
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* FT_ANGLE_PI4
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*
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* @description:
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* The angle pi/4 expressed in @FT_Angle units.
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*
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*/
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#define FT_ANGLE_PI4 ( FT_ANGLE_PI / 4 )
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/**************************************************************************
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*
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* @function:
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* FT_Sin
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*
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* @description:
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* Return the sinus of a given angle in fixed-point format.
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*
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* @input:
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* angle ::
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* The input angle.
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*
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* @return:
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* The sinus value.
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*
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* @note:
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* If you need both the sinus and cosinus for a given angle, use the
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* function @FT_Vector_Unit.
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*
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*/
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FT_EXPORT( FT_Fixed )
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FT_Sin( FT_Angle angle );
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/**************************************************************************
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*
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* @function:
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* FT_Cos
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*
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* @description:
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* Return the cosinus of a given angle in fixed-point format.
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*
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* @input:
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* angle ::
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* The input angle.
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*
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* @return:
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* The cosinus value.
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*
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* @note:
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* If you need both the sinus and cosinus for a given angle, use the
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* function @FT_Vector_Unit.
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*
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*/
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FT_EXPORT( FT_Fixed )
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FT_Cos( FT_Angle angle );
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/**************************************************************************
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*
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* @function:
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* FT_Tan
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*
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* @description:
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* Return the tangent of a given angle in fixed-point format.
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*
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* @input:
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* angle ::
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* The input angle.
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*
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* @return:
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* The tangent value.
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*
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*/
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FT_EXPORT( FT_Fixed )
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FT_Tan( FT_Angle angle );
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/**************************************************************************
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*
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* @function:
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* FT_Atan2
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*
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* @description:
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* Return the arc-tangent corresponding to a given vector (x,y) in the 2d
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* plane.
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*
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* @input:
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* x ::
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* The horizontal vector coordinate.
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*
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* y ::
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* The vertical vector coordinate.
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*
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* @return:
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* The arc-tangent value (i.e. angle).
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*
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*/
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FT_EXPORT( FT_Angle )
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FT_Atan2( FT_Fixed x,
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FT_Fixed y );
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/**************************************************************************
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*
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* @function:
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* FT_Angle_Diff
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*
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* @description:
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* Return the difference between two angles. The result is always
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* constrained to the ]-PI..PI] interval.
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*
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* @input:
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* angle1 ::
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* First angle.
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*
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* angle2 ::
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* Second angle.
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*
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* @return:
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* Constrained value of `angle2-angle1`.
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*
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*/
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FT_EXPORT( FT_Angle )
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FT_Angle_Diff( FT_Angle angle1,
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FT_Angle angle2 );
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/**************************************************************************
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*
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* @function:
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* FT_Vector_Unit
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*
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* @description:
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* Return the unit vector corresponding to a given angle. After the
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* call, the value of `vec.x` will be `cos(angle)`, and the value of
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* `vec.y` will be `sin(angle)`.
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*
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* This function is useful to retrieve both the sinus and cosinus of a
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* given angle quickly.
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*
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* @output:
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* vec ::
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* The address of target vector.
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*
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* @input:
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* angle ::
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* The input angle.
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*
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*/
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FT_EXPORT( void )
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FT_Vector_Unit( FT_Vector* vec,
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FT_Angle angle );
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/**************************************************************************
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*
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* @function:
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* FT_Vector_Rotate
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*
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* @description:
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* Rotate a vector by a given angle.
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*
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* @inout:
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* vec ::
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* The address of target vector.
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*
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* @input:
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* angle ::
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* The input angle.
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*
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*/
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FT_EXPORT( void )
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FT_Vector_Rotate( FT_Vector* vec,
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FT_Angle angle );
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/**************************************************************************
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*
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* @function:
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* FT_Vector_Length
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*
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* @description:
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* Return the length of a given vector.
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*
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* @input:
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* vec ::
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* The address of target vector.
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*
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* @return:
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* The vector length, expressed in the same units that the original
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* vector coordinates.
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*
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*/
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FT_EXPORT( FT_Fixed )
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FT_Vector_Length( FT_Vector* vec );
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/**************************************************************************
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*
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* @function:
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* FT_Vector_Polarize
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*
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* @description:
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* Compute both the length and angle of a given vector.
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*
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* @input:
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* vec ::
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* The address of source vector.
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*
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* @output:
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* length ::
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* The vector length.
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*
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* angle ::
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* The vector angle.
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*
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*/
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FT_EXPORT( void )
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FT_Vector_Polarize( FT_Vector* vec,
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FT_Fixed *length,
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FT_Angle *angle );
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/**************************************************************************
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*
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* @function:
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* FT_Vector_From_Polar
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*
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* @description:
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* Compute vector coordinates from a length and angle.
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*
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* @output:
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* vec ::
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* The address of source vector.
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*
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* @input:
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* length ::
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* The vector length.
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*
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* angle ::
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* The vector angle.
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*
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*/
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FT_EXPORT( void )
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FT_Vector_From_Polar( FT_Vector* vec,
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FT_Fixed length,
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FT_Angle angle );
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/* */
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FT_END_HEADER
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#endif /* FTTRIGON_H_ */
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/* END */
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