/* CIRCLE.C -- by Gary Neal, Jr.
 *
 * This function draws a circle on the graphics screen using floating
 * point math.
 */

#include "fgraph.h"             /* Needed for ScreenWidth & ScreenHeight */

float angleIncr = 0.5;

void Circle(int xOffset, int yOffset, int radius, unsigned char C)
{
     float xPlot, yPlot;        /* Current pixel being plotted */
     float angle, angleRad;     /* Current angle degrees & radiens */

     /* Check limits for Angle Increment */
     if (angleIncr < 1) angleIncr = 0.5;
     else if (angleIncr > 360.) angleIncr = 360.;

     for (angle = 0.; angle < 360.; angle += angleIncr) {

          /* Convert degrees to radiens */
          angleRad = angle * (3.141592654 / 180);

          /* Convert polar to rectangular coordinates */
          xPlot = (radius * cos(angleRad)) + xOffset;
          yPlot = (radius * sin(angleRad)) + yOffset;

          /* Check boundaries */
          if (xPlot < 0)
               xPlot = 0;
          else if (xPlot >= ScreenWidth)
               xPlot = ScreenWidth - 1;

          if (yPlot < 0)
               yPlot = 0;
          else if (yPlot >= ScreenHeight)
               yPlot = ScreenHeight - 1;

          /* Plot the pixel on the graphics screen */
          SetPixel((int)xPlot, (int)yPlot, C);
     }
}