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Inside Macintosh: Operating System Utilities /

Chapter 3 - Mathematical and Logical Utilities / Mathematical and Logical Utilities Reference

Routines / Converting Between Angle and Slope Values

SlopeFromAngle

You can convert an angle value to a slope value using the SlopeFromAngle function.

FUNCTION SlopeFromAngle (angle: Integer): Fixed;

angle

The angle, expressed in clockwise degrees from 12 o'clock and treated MOD 180. (90 degrees is thus at 3 o'clock and -90 degrees is at 9 o'clock.)

DESCRIPTION

The SlopeFromAngle function returns the slope corresponding to the angle specified in the angle parameter. Slopes are defined as Dx/Dy, the horizontal change divided by the vertical change between any two points on a line with the given angle. The negative y-axis is defined as being at 12 o'clock, and the positive y-axis at 6 o'clock. The x-axis is defined as usual, with the positive side defined as being at 3 o'clock.

SEE ALSO

For an example of the use of the SlopeFromAngle function, see Figure 3-7 on page 3-13.