*/ + /* 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 */