Re: Set Sided Polygon in C++

**What** does not work as you expected?

Re: Set Sided Polygon in C++

I do not understand your algorithm. Perhaps there is something I am missing. It seems to me that if one specifies a polygon with the number of sides greater than or equal to 3, there are an infinite number of possible such polygons. Thus one would need to specify the length of each side and some clever algorithm to determine the angles between each side (such algorithms exist - try google). For more details, see:

http://www.mathleague.com/help/geome...ns.htm#polygon

After further thought I realized you must by trying to inscribe a regular polygon ( all sides equal ) on a circle. You will need some algorithm to divide the circumference of the circle into N+1 segments, then draw lines from each segment point to the next going around the circle. The math shouldnt be to difficult. I would be interested in seeing how you solve the problem.

Hope this is helpful :)

Re: Set Sided Polygon in C++

I've almost got it figured, I've got it too do one side of the polygon when a given side is given.

Basically I'm struggling too create it with an infinite number of sides.

Re: Set Sided Polygon in C++

Anyone have any idea how I would do this, been trying to figure it out for ages!

Re: Set Sided Polygon in C++

Quote:

Originally Posted by

**Mike Pliam**
It seems to me that if one specifies a polygon with the number of sides greater than or equal to 3, there are an infinite number of possible such polygons.

A polygon with less than three sides is an interesting concept... :D Aside from that: The possibilities of any polygon (number of sides >= 3) are infinite unless you specify some parameters. Even if you postulate a regular polygon they're infinite unless you specify a center and a starting point (e.g.).

Quote:

Originally Posted by

**abakiz**
Basically I'm struggling too create it with an infinite number of sides.

Hint: A regular polygon with an infinite number of sides is a circle.

Aside from that: http://en.wikipedia.org/wiki/Polygon

Re: Set Sided Polygon in C++

I see what your saying, but what sort of algorithm could I do this with?

Re: Set Sided Polygon in C++

What I got so far:

Code:

int x = X;

int y = Y;

//The radious, half of the circle length

int r = R;

int sides = Sides;

float cir = PI * (r * 2);

//basically saying, the edgelength and shave off the bit when you curve it straight, so you get the true length of each side.

float edgelength = (cir / sides) - ((cir / sides) / PI);

//splitting the angle of the sides

float angle = cir / sides;

//you need to rotate or move the line to the next angle / side or something.

float EndX_Y;

Re: Set Sided Polygon in C++

The point on a circle centered on (xc,yc) with radius r are given by

x = xc + r*cos(angle)

y = yc + r*sin(angle)

Code:

`void PixelPlotterForm::DrawPolygon( int Sides, int X, int Y, int R )`

{

double xc = X;

double yc = Y;

double radius = R;

double angle_step = 2.0 * PI / static_cast<double>(Sides);

for (int i=0; i<Sides; ++i)

{

double angle = angle_step * i;

double x = xc + radius*cos(angle);

double y = yc + radius*sin(angle);

}

}

Re: Set Sided Polygon in C++

abakiz, did you manage to fix this issue? Im working on something similar and as I am new to this struggling with:

void PixelPlotterForm::DrawRectangle( int X, int Y, int Width, int Height, Color PixelColour )