title: "Atan2" description: TRSE built-in method (from IDE help)

`Atan2`

Systems: X16,C64, MEGA65, PLUS4, C128, VIC20, PET, NES , OK64, BBCM, ACORN, ATARI800
Parameters: b,b,b,b

[byte angle] = Atan2( [byte x1], [byte x2], [byte y1], [byte y2] );

[byte x1] - x value 1
[byte x2] - x value 2
[byte y1] - y value 1
[byte y2] - y value 2

Description

Returns atan2 of the arguments (x2-x1, y2-y1) (Atan2 calculates the angle between two points x and y). Note, if using sprite x positions, scale the x and y positions by half for the Atan2 parameters.

The return result is a value between 0 and 255, where:

3 o'clock = 0
6 o'clock = 63
9 o'clock = 127
12 o'clock = 192

Example


program MyProgram;
var
    x1, x2, y1, y2, angle : byte;

begin

        ClearScreen(32, ^$0400);

        x1 := 100;  y1 := 100;
        x2 := 200;  y2 := 100;  // position 2 is at 3 o'clock from position 1

        angle := Atan2(x1, x2, y1, y2);

        MoveTo(0,0,$04);
        PrintDecimal(angle, 6);

        Loop();

end.