Circle filling algorithm?

FxMazter · 2003-01-04T02:00:41

Hello! I made an algorithm for drawing and filling a circle with pixels. But hence, it doesn't work at all... the pixels get spread all over the screen. Here is how it looks: //Algorith for plotting a circle filled with pixels int nRadie = 50; double pi = 3.1415926535; for(double v=(pi/180); v <= (2*pi); v+=(pi/180)) { for(int z=1; z<=(nRadie); z++) { int y = (int)((z)/(sin(v)))+100; int x = (int)((cos(v))*z)+100; Plot32BitPixel(x, y, color, pixelBuffer, nPitch); } } Ok, I'm no genious in neighter programming nor maths, so thes could probably be done much better but, shouldn't I at least get somewhat a circular object painted with this?? as you can see, the v is incremented with 1 degree for 360 degrees but is written in radians. Can anyone figure out why this is so TOTALLY wrong? I have tried to make this algorith according to these mathematical laws: sin v = a/c cos v = b/c y-coordinate ^ | /| | c/ |a | / | |/v__|___ > x-coordinate b a, b, c = lenght of the sides on the triangle v = degrees between y = 0 and the current y value (triangle in a Coordinate system) THX! [edited by - FxMazter on December 23, 2002 6:51:34 PM] [edited by - FxMazter on December 23, 2002 6:55:27 PM] [edited by - FxMazter on December 23, 2002 6:57:26 PM] [edited by - FxMazter on December 23, 2002 6:58:17 PM] [edited by - FxMazter on December 23, 2002 7:00:32 PM] [edited by - FxMazter on December 23, 2002 7:02:13 PM]

Math and Physics Programming

Started by FxMazter December 23, 2002 05:39 PM

9 comments, last by FxMazter 22 years, 1 month ago

Zipster

2,420

January 04, 2003 02:00 AM

While we''re all posting circle-render code, I just have to chime in with my own algorithm

for(int h = radius; h >= -radius; --h){   int w = 2 * sqrt( radius*radius - h*h );   int local_x = X - (w / 2);   int local_y = Y - h;   Rectangle(local_x, local_y, w, 1, color_r, color_g, color_b, color_a);}

Rectangle is such a trivial function to code, I''m sure you can handle that

If you want an unfilled circle, then simply draw a pixel at the start and end points.