214 lines
5.3 KiB
C
214 lines
5.3 KiB
C
#ifndef __FT_TRIGONOMETRY_H__
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#define __FT_TRIGONOMETRY_H__
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FT_BEGIN_HEADER
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/***************************************************************************
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*
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* @section: computations
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*
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*/
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/***************************************************************************
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*
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* @type: 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
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* the angle is a 16.16 fixed float value expressed in _degrees_
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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: 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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#define FT_ANGLE_PI (180L << 16)
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/***************************************************************************
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*
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* @macro: FT_ANGLE_2PI
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*
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* @description:
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* the angle 2pi expressed in @FT_Angle units
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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: 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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#define FT_ANGLE_PI2 (FT_ANGLE_PI/2)
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/***************************************************************************
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*
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* @macro: 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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#define FT_ANGLE_PI4 (FT_ANGLE_PI/4)
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/***************************************************************************
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*
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* @function: 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 :: input angle
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*
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* @return:
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* 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, you'd
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* better use the function @FT_Vector_Unit
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*/
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FT_EXPORT(FT_Fixed) FT_Sin( FT_Angle angle );
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/***************************************************************************
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*
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* @function: 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 :: input angle
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*
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* @return:
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* 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, you'd
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* better use the function @FT_Vector_Unit
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*/
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FT_EXPORT(FT_Fixed) FT_Cos( FT_Angle angle );
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/***************************************************************************
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*
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* @function: 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 :: input angle
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*
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* @return:
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* tangent value
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*/
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FT_EXPORT(FT_Fixed) FT_Tan( FT_Angle angle );
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/***************************************************************************
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*
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* @function: 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
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* the 2d plane
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*
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* @input:
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* x :: horizontal vector coordinate
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* y :: vertical vector coordinate
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*
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* @return:
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* arc-tangent value (i.e. angle)
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*/
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FT_EXPORT(FT_Angle) FT_Atan2( FT_Fixed x, FT_Fixed y );
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/***************************************************************************
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*
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* @function: 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 call,
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* the value of "vec.x" will be "sin(theta)", and the value of "vec.y"
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* will be "cos(angle)"
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*
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* this function is useful to retrieve both the sinus and cosinus
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* of a given angle quickly
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*
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* @input:
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* vec :: address of target vector
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* angle :: address of angle
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*/
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FT_EXPORT(void) 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: FT_Vector_Rotate
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*
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* @description:
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* rotate a given vector by a given angle
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*
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* @input:
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* vec :: address of target vector
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* angle :: address of angle
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*/
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FT_EXPORT(void) 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: FT_Vector_Length
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*
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* @description:
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* returns the length of a given vector
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*
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* @input:
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* vec :: address of target vector
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*
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* @return:
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* vector length, expressed in the same units that the original
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* vector coordinates !!
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*/
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FT_EXPORT(FT_Fixed) FT_Vector_Length( FT_Vector* vec );
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/***************************************************************************
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*
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* @function: FT_Vector_Normalize
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*
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* @description:
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* normalize a given vector (i.e. compute the equivalent unit vector)
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*
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* @input:
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* vec :: address of target vector
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*/
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FT_EXPORT(void) FT_Vector_Normalize( FT_Vector* vec );
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/***************************************************************************
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*
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* @function: 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 :: address of source vector
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*
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* @output:
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* length :: vector length
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* angle :: vector angle
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*/
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FT_EXPORT(void) 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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FT_END_HEADER
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#endif /* __FT_TRIGONOMETRY_H__ */
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