Archimedean spiral: Difference between revisions

=={{header|Action!}}==

Action! does not provide trigonometric functions. Therefore a simple implementation for Sin and Cos function has been provided.

<lang Action!>INT ARRAY SinTab=[

0 4 9 13 18 22 27 31 36 40 44 49 53 58 62 66 71 75 79 83

88 92 96 100 104 108 112 116 120 124 128 132 136 139 143

147 150 154 158 161 165 168 171 175 178 181 184 187 190

193 196 199 202 204 207 210 212 215 217 219 222 224 226

228 230 232 234 236 237 239 241 242 243 245 246 247 248

249 250 251 252 253 254 254 255 255 255 256 256 256 256]

INT FUNC Sin(INT a)

WHILE a<0 DO a==+360 OD

WHILE a>360 DO a==-360 OD

IF a<=90 THEN

RETURN (SinTab(a))

ELSEIF a<=180 THEN

RETURN (SinTab(180-a))

ELSEIF a<=270 THEN

RETURN (-SinTab(a-180))

ELSE

RETURN (-SinTab(360-a))

FI

RETURN (0)

INT FUNC Cos(INT a)

RETURN (Sin(a-90))

PROC DrawSpiral(INT x0,y0)

INT angle,radius,x,y

Plot(x0,y0)

FOR angle=0 TO 1800 STEP 5

DO

radius=angle/20

x=radius*Cos(angle)/256+x0

y=radius*Sin(angle)/256+y0

DrawTo(x,y)

OD

RETURN

PROC Main()

BYTE CH=$02FC,COLOR1=$02C5,COLOR2=$02C6

Graphics(8+16)

Color=1

COLOR1=$0C

COLOR2=$02

DrawSpiral(160,96)

DO UNTIL CH#$FF OD

CH=$FF

RETURN</lang>

{{out}}

[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Archimedean_spiral.png Screenshot from Atari 8-bit computer]