### Re: Spiral

- Posted by Michael Packard <lgp at EXO.COM> Nov 10, 1996
- 1474 views

On Sat, 9 Nov 1996, John Waldrep wrote: > > I would greatly appreciate it anyone could send me a small program to > generate a black and white spiral. You never gave us any more info, so here's a Black and GREEN 2D spiral: The general equation for a spiral in polar coordinates is r=theta, which is x=r*(sin(theta)) y=r*(cos(theta)) in rectangular. To display this on the screen, you need to multiply x and y by a size factor and add an offset shift the coordinate axis to the center of the screen. In this example the we're in 640x480x16 color mode, so we add 320 to x and 240 to y to center the spiral on the screen. -- spiral.ex without type_check include graphics.e include select.e include get.e constant GRAPHICS_MODE = 18 -- VGA atom size atom x atom y -- switch to graphics screen if not select_mode(GRAPHICS_MODE) then puts(1, "needs VGA graphics\n") abort(1) end if -- spiral for i = 1 to 10 by .5 do --do the spiral is different sizes size =i for r = 0 to 80 by .01 do x=size*r*sin(r)+320 y=size*r*cos(r)+240 pixel(10,{x,y}) end for --Don't clear the screen the last time. if i <10 then clear_screen() end if end for x=wait_key() if graphics_mode(-1) then end if --------------------------------- see, I didn't go to college for nothing... It cost me THOUSANDS AND THOUSANDS of dollars... (yes, I have a math degree) Michael Packard Lord Generic Productions lgp at exo.com http://exo.com/~lgp A Crash Course in Game Design and Production http://exo.com/~lgp/euphoria