trig_lut.h File Reference

fixed point trig functions. Angle can be in the range of -32768 to 32767. There are 32768 degrees in the unit circle used by nds. To convert between standard degrees (360 per circle): More...

#include <nds/ndstypes.h>

Defines
#define	angleToDegrees(angle)   ((angle) * 360 / DEGREES_IN_CIRCLE)
	converts an angle in the format used by libnds in the 360 degree format.
#define	DEGREES_IN_CIRCLE   (1 << 15)
	number of degrees in a circle.
#define	degreesToAngle(degrees)   ((degrees) * DEGREES_IN_CIRCLE / 360)
	convert an angle in 360 degree format to the format used by libnds.
#define	fixedToFloat(n, bits)   (((float)(n)) / (float)(1<<(bits)))
	converts a fixed point number to a floating point number.
#define	fixedToInt(n, bits)   ((int)((n)>>(bits)))
	convert a fixed point number to an integer.
#define	floatToFixed(n, bits)   ((int)((n) * (float)(1<<(bits))))
	converts a floating point number to a fixed point number.
#define	floorFixed(n, bits)   ((int)((n) & ~(((1 << (bits)) - 1))))
	removes the decimal part of a fixed point number.
#define	intToFixed(n, bits)   ((int)((n)<<(bits)))
	converts an integer to a fixed point number.
Functions
s16	acosLerp (s16 par)
	fixed point arccos
s16	asinLerp (s16 par)
	fixed point arcsin
s16	cosLerp (s16 angle)
	fixed point cosine
s16	sinLerp (s16 angle)
	fixed point sine
s32	tanLerp (s16 angle)
	fixed point tangent

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Detailed Description

fixed point trig functions. Angle can be in the range of -32768 to 32767. There are 32768 degrees in the unit circle used by nds. To convert between standard degrees (360 per circle):

angle = degreesToAngle(angleInDegrees);

or

angle = angleInDegrees * 32768 / 360;

This unit of measure is sometimes refered to as a binary radian (brad) or binary degree. It allows for more precise representation of angle and faster calculation as the DS has no floating point processor.

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Define Documentation

#define fixedToFloat	(	n,
		bits		)	(((float)(n)) / (float)(1<<(bits)))

converts a fixed point number to a floating point number.

Parameters:

	n	the fixed point number to convert.
	bits	the number of bits used for the decimal part.

Returns:

the floating point number.

#define fixedToInt	(	n,
		bits		)	((int)((n)>>(bits)))

convert a fixed point number to an integer.

Parameters:

	n	the number the number to convert.
	bits	the number of bits used for the decimal part.

Returns:

the integer part.

#define floatToFixed	(	n,
		bits		)	((int)((n) * (float)(1<<(bits))))

converts a floating point number to a fixed point number.

Parameters:

	n	the floating point number to convert.
	bits	the number of bits used for the decimal part.

Returns:

the fixed point number.

#define floorFixed	(	n,
		bits		)	((int)((n) & ~(((1 << (bits)) - 1))))

removes the decimal part of a fixed point number.

Parameters:

	n	the fixed point number.
	bits	the number of bits used for the decimal part.

Returns:

a fixed point number with 0 as a decimal part.

#define intToFixed	(	n,
		bits		)	((int)((n)<<(bits)))

converts an integer to a fixed point number.

Parameters:

	n	the integer to convert.
	bits	the number of bits used for the decimal part.

Returns:

the fixed point number.

Examples:

Graphics/Printing/rotscale_text/source/main.c, and Graphics/Sprites/sprite_rotate/source/template.c.

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Function Documentation

s16 acosLerp

(

s16

par

)

fixed point arccos

Parameters:

par

parameter

Returns:

s16 angle (-32768 to 32767)

s16 asinLerp

(

s16

par

)

fixed point arcsin

Parameters:

par

parameter

Returns:

s16 angle (-32768 to 32767)

s16 cosLerp

(

s16

angle

)

fixed point cosine

Parameters:

angle

(-32768 to 32767)

Returns:

4.12 fixed point number with the range [-1, 1]

Examples:

capture/ScreenShot/source/main.cpp, Graphics/3D/nehe/lesson10/source/nehe10.cpp, Graphics/3D/nehe/lesson10b/source/nehe10b.cpp, Graphics/3D/nehe/lesson11/source/nehe11.cpp, and input/Touch_Pad/touch_look/source/main.cpp.

s16 sinLerp

(

s16

angle

)

fixed point sine

Parameters:

angle

(-32768 to 32767)

Returns:

4.12 fixed point number with the range [-1, 1]

Examples:

audio/maxmod/streaming/source/main.c, capture/ScreenShot/source/main.cpp, Graphics/3D/nehe/lesson10/source/nehe10.cpp, Graphics/3D/nehe/lesson10b/source/nehe10b.cpp, Graphics/3D/nehe/lesson11/source/nehe11.cpp, and input/Touch_Pad/touch_look/source/main.cpp.

s32 tanLerp

(

s16

angle

)

fixed point tangent

Parameters:

angle

(-32768 to 32767)

Returns:

20.12 fixed point number with the range [-81.483, 524287.999]