Math routines.
Below is a code example that uses the trigonometry functions to calculate the coordinate at which the second hand of a watch ends, using seconds from the system time.
GPoint secondHand;
GPoint center;
struct tm *tick_time = ...;
int32_t secondHandLength = ...;
...
int32_t second_angle = TRIG_MAX_ANGLE * tick_time->tm_sec / 60;
secondHand.y = (-cos_lookup(second_angle) * secondHandLength / TRIG_MAX_RATIO) + center.y;
secondHand.x = (sin_lookup(second_angle) * secondHandLength / TRIG_MAX_RATIO) + center.x;
Look-up the sine of the given angle from a pre-computed table.
The angle for which to compute the cosine. The angle value is scaled linearly, such that a value of 0x10000 corresponds to 360 degrees or 2 PI radians.
Look-up the cosine of the given angle from a pre-computed table. This is equivalent to calling sin_lookup(angle + TRIG_MAX_ANGLE / 4).
The angle for which to compute the cosine. The angle value is scaled linearly, such that a value of 0x10000 corresponds to 360 degrees or 2 PI radians.
Look-up the arctangent of a given x, y pair The angle value is scaled linearly, such that a value of 0x10000 corresponds to 360 degrees or 2 PI radians.
The largest value that can result from a call to sin_lookup or cos_lookup. For a code example, see the detailed description at the top of this chapter: Math.
Converts from a fixed point value representation to the equivalent value in degrees.
Converts from an angle in degrees to the equivalent fixed point value representation.
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