Thread: drawing a spiral

hey everyone, i want to write a program that will draw a spiral, and will have as many "rings" in it as the user says. im very very new to c, so im kinda confused. btw, this is NOT a hw assignment, my teacher just introduced using graphics today, but i really want to figure out how to make this program because not knowing how to do things like this really bothers me. thanks for the help.
i think everything is right, but i just dont know what goes inside the for() loop, which needs to be what actually draws the spiral.


/*
*This program will draw a spiral with as many rings as the user
*specifies
*/

#include <stdio.h>
#include "genlib.h"
#include "graphics.h"



main()
{

double xmax, ymax, i;
int rings;


InitGraphics();
LogCommands(TRUE);
xmax = GetWindowWidth();
ymax = GetWindowHeight();

printf("How many rings do you want in the spiral?:");
scanf("%d", &rings);


for(i=0; i<rings; i++)
{


}

ExitGraphics(); /*‘hit any key’ */
return(0);


}

thanks, ill read over that site, hopefully ill be able to get it myself.

whoa, that site is crazy! i dont understand half the stuff on it. i dont care that there are 15 different types of spirals, or what a spiral is, or where the word spiral came from, i just need to know the c commands that will allow me to draw a spiral.

how can i incorporate trig functions into my code? i tried making a variable = to cos(theta), but it said cos was undefined, and some crap about theta. is there a symbol in c for theta(the thing that looks like a 0)? thanks for the help.

Originally posted by Unregistered
how can i incorporate trig functions into my code? i tried making a variable = to cos(theta), but it said cos was undefined, and some crap about theta. is there a symbol in c for theta(the thing that looks like a 0)? thanks for the help.

#include <math.h>
sorry cant help you about the theta

thanks for that info.

i really cant believe that of all the people on this board, no one knows how to draw a simple spiral. id really appreciate any help.
thanks again to anyone who can

hey i think maybe you want to look for a function in C that will plot a point and call it repeatedly, but make it follow a pattern for the points along one of the trigonometric funtions, if you set it up and think about it in a polar plane and not on a coordinate plane, then I seem to remember back to one of my calc classes that you can make a spiral using one of the trig functions on a polar plane. Now all you have to do then is convert polar to coordinate (which is VERY possible, and not too hard from what i remember) and then plot the point along that.
it sounds very difficult but i think it will prove to be simple, I do suggest reading some advanced mathematics books to follow through with it htough, it will give you a better sense of an algorythim to do it.

-hope i helped, if not, just ignore me, it is just a thought, from what i could concieve . -- the fish.

i added some more stuff, but it only draws a small line. this isreally confusing to me.
i appreciate anyhelp.


/*
*This program will draw a spiral with as many rings as the user
*specifies
*/

#include <stdio.h>
#include "genlib.h"
#include "graphics.h"
#include <math.h>

main()
{

double xmax, ymax, oldx, newx, oldy, newy, ring, diameter, x, y, degrees, i;

ring=20;


InitGraphics();
LogCommands(TRUE); /*print drawing cmds */
xmax = GetWindowWidth(); /* usually 7.0 */
ymax = GetWindowHeight(); /* usually 6.0 */
MovePen(-20, 20);
if (degrees == 360)
{
degrees = 0;
ring = ring--;
}
else { degrees++;}


for(i=0; i<ring; i++)
{

diameter = diameter + 0.01;
degrees = degrees + 0.01;
diameter=1;
degrees=1;

x = diameter * sin(degrees);
y = diameter * cos(degrees);

oldx=GetCurrentX();
oldy=GetCurrentY();
MovePen(x, y);
DrawLine(oldx-x, oldy-y);
MovePen(x, y);


}




ExitGraphics();
return(0);


}