C语言设计
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发布时间：2022-04-19 15:32
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时间：2023-07-20 09:43
//仅供参考：
double angleOf(double x, double y) {
double dist=sqrt(x*x+y*y) ;
if (y>=0.) return acos( x/dist) ;
else return acos(-x/dist)+.5*CIRCLE_RADIANS; }
// Pass in a set of 2D points in x,y,points. Returns a polygon in polyX,polyY,polyCorners.
//
// To be safe, polyX and polyY should have enough space to store all the points passed in x,y,points.
void findSmallestPolygon(double *x, double *y, long points, double *polyX, double *polyY, long *polyCorners) {
double newX=x[0], newY=y[0], xDif, yDif, oldAngle=.5*CIRCLE_RADIANS, newAngle, angleDif, minAngleDif ;
long i ;
// Find a starting point.
for (i=0; i<points; i++) if (y[i]>newY || y[i]==newY && x[i]<newX) {
newX=x[i]; newY=y[i]; }
*polyCorners=0;
// Polygon-construction loop.
while (!(*polyCorners) || newX!=polyX[0] || newY!=polyY[0]) {
polyX[*polyCorners]=newX;
polyY[*polyCorners]=newY; minAngleDif=CIRCLE_RADIANS;
for (i=0; i<points; i++) {
xDif=x[i]-polyX[*polyCorners];
yDif=y[i]-polyY[*polyCorners];
if (xDif || yDif) {
newAngle=angleOf(xDif,yDif); angleDif =oldAngle-newAngle;
while (angleDif< 0. ) angleDif+=CIRCLE_RADIANS;
while (angleDif>=CIRCLE_RADIANS) angleDif-=CIRCLE_RADIANS;
if (angleDif<minAngleDif) {
minAngleDif=angleDif; newX=x[i]; newY=y[i]; }}}
(*polyCorners)++; oldAngle+=.5*CIRCLE_RADIANS-minAngleDif; }}
