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Clutter 0.2 Reference Manual | ![]() |
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typedef ClutterFixed; #define CFX_Q #define CFX_ONE #define CFX_MAX #define CFX_MIN typedef ClutterAngle; #define CFX_PI #define CFX_2PI #define CFX_PI_2 #define CFX_PI_4 #define CFX_120 #define CFX_180 #define CFX_240 #define CFX_360 #define CFX_60 #define CFX_255 #define CFX_DIV #define CFX_INT #define CFX_MUL #define CLUTTER_FIXED_TO_FLOAT (x) #define CLUTTER_FIXED_TO_DOUBLE (x) #define CLUTTER_FLOAT_TO_FIXED (x) #define CLUTTER_INT_TO_FIXED (x) #define CLUTTER_FIXED_INT (x) #define CLUTTER_FIXED_FRACTION (x) #define CLUTTER_FIXED_FLOOR (x) #define CLUTTER_FIXED_CEIL (x) #define CLUTTER_FIXED_MUL (x,y) #define CLUTTER_FIXED_DIV (x,y) #define clutter_cosi (angle) #define clutter_cosx (angle) ClutterFixed clutter_sini (ClutterAngle angle); ClutterFixed clutter_sinx (ClutterFixed angle); gint clutter_sqrti (gint x); ClutterFixed clutter_sqrtx (ClutterFixed x);
Clutter has a fixed point API targeted at platforms without a floating point unit, such as embedded devices. This API should be preferred to the floating point one as it does not trigger the slow path of software emulation, relying on integer math for fixed-to-floating and floating-to-fixed conversion.
Two fixed point numbers can be directly added and subtracted.
To add other numerical type to a fixed point number it has to be first converted to fixed point.
A fixed point number can be directly multiplied or divided by an integer.
Two fixed point numbers can only be multiplied and divided by the provided CLUTTER_FIXED_MUL (aka CFX_MUL) and CLUTTER_FIXED_DIV (aka CFX_DIV) macros.
#define CFX_Q 16 /* Decimal part size in bits */
Number of bits used to store fractional part of ClutterFixed.
typedef gint32 ClutterAngle; /* angle such that 1024 == 2*PI */
Integer representation of an angle such that 1024 corresponds to full circle (i.e., 2*Pi).
#define CLUTTER_FIXED_TO_FLOAT(x) ((float) ((int)(x) / 65536.0))
Macro for converting ClutterFixed to single precission floating point.
x : |
ClutterFixed |
#define CLUTTER_FIXED_TO_DOUBLE(x) ((double) ((int)(x) / 65536.0))
Macro for converting ClutterFixed to double precission floating point.
x : |
ClutterFixed |
#define CLUTTER_FLOAT_TO_FIXED(x) _clutter_double_to_fixed((x))
Macro for converting floating point numbers to ClutterFixed.
x : |
double or float |
#define CLUTTER_INT_TO_FIXED(x) ((x) << CFX_Q)
Macro for converting integers to ClutterFixed.
x : |
int |
#define CLUTTER_FIXED_INT(x) ((x) >> CFX_Q)
Macro to obtain integer part of ClutterFixed.
x : |
ClutterFixed |
#define CLUTTER_FIXED_FRACTION(x) ((x) & ((1 << CFX_Q) - 1))
Macro to obtain the fraction of ClutterFixed.
x : |
ClutterFixed |
#define CLUTTER_FIXED_FLOOR(x)
Macro to obtain greatest integer smaller than given ClutterFixed.
x : |
ClutterFixed |
#define CLUTTER_FIXED_CEIL(x) CLUTTER_FIXED_FLOOR(x + 0xffff)
Macro to obtain smallest integer greater than given ClutterFixed.
x : |
ClutterFixed |
#define CLUTTER_FIXED_MUL(x,y) ((x) >> 8) * ((y) >> 8)
Macro for multiplication of two ClutterFixed numbers.
x : |
ClutterFixed |
y : |
ClutterFixed |
#define CLUTTER_FIXED_DIV(x,y) ((((x) << 8)/(y)) << 8)
Macro for difvision of two ClutterFixed numbers.
x : |
ClutterFixed |
y : |
ClutterFixed |
#define clutter_cosi(angle) clutter_sini((angle) - 256)
Very fast fixed point implementation of cosine function.
ClutterAngle is an integer such that 1024 represents full circle.
angle : |
a ClutterAngle angle |
Since 0.2
#define clutter_cosx(angle) clutter_fixed_sin((angle) - CFX_PI_2)
Fixed point cosine function
angle : |
a ClutterFixed angle in radians |
Since 0.2
ClutterFixed clutter_sini (ClutterAngle angle);
Very fast fixed point implementation of sine function.
ClutterAngle is an integer such that 1024 represents full circle.
angle : |
a ClutterAngle |
Returns : | ClutterFixed sine value. |
Since 0.2
ClutterFixed clutter_sinx (ClutterFixed angle);
Fixed point implementation of sine function
angle : |
a ClutterFixed angle in radians |
Returns : | ClutterFixed sine value. |
Since 0.2
gint clutter_sqrti (gint x);
Very fast fixed point implementation of square root for integers.
This function is about 10x faster than clib sqrt()
on x86, and (this is
not a typo!) more than 800x faster on ARM without FPU. It's error is < 5%
for arguments < 132 and < 10% for arguments < 5591.
x : |
integer value |
Returns : | integer square root. |
Since 0.2
ClutterFixed clutter_sqrtx (ClutterFixed x);
A fixed point implementation of squre root
x : |
a ClutterFixed |
Returns : | ClutterFixed square root. |
Since 0.2