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+/***************************************************************************/
+/* */
+/* fttrigon.h */
+/* */
+/* FreeType trigonometric functions (specification). */
+/* */
+/* Copyright 2001, 2003, 2005, 2007 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 FT_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 float 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 `value2-value1'.
+ *
+ */
+ 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 `sin(angle)', and the value of
+ * `vec.y' will be `cos(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 address of 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 address of 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 */