计算几何源码
本人收集的一些计算几何源码，包括判断点是否在多边形内，计算多边形面积、方向，直线、线段相交的源码。bool collinear(double x1, double y1, double x2, double y2, double x3, double y3, double epsilon)
{
return (fabs((x2 - x1) * (y3 - y1)- (x3 - x1) * (y2 - y1)) <= epsilon);
}
bool point_in_polygon(double px, double py, const polygon<double, 2> &polygon)
{
bool result = false;
if (polygon.size() < 3)
return false;
std::size_t j = polygon.size() - 1;
for(std::size_t i = 0; i < polygon.size(); ++i)
{
if (((polygon.y <= py) && (py < polygon.y)) || ((polygon.y <= py) && (py < polygon.y)))
{
if (px - polygon.x < ((polygon.x - polygon.x) * (py - polygon.y) / (polygon.y - polygon.y)))
{
result = !result;
}
}
j = i;
}
return result;
}
int polygon_orientation(LPPOINT pp, int n)
{
double t = 0;
for(int i = 1; i <= n-1; i++)
t += pp.x*pp.y - pp.x*pp.y;
t += pp.x*pp.y - pp.x*pp.y;
return t < 0 ? CounterClockwise : Clockwise;
}
int polygon_orientation(const polygon<T, 2> &polygon)
{
if(polygon.size() < 3)
{
return 0;
}
double area = double(0.0);
std::size_t prev_index = polygon.size() - 1;
for(std::size_t index = 0; index < polygon.size(); ++index)
{
area += (polygon.x * polygon.y - polygon.x * polygon.y);
prev_index = index;
}
return (((area >= double(0.0))) ? CounterClockwise : Clockwise);
}
double area(const polygon<double,2>& polygon)
{
if(polygon.size() < 3)
return double(0.0);
double result = double(0.0);
std::size_t j = polygon.size() - 1;
for(std::size_t i = 0; i < polygon.size(); ++i)
{
result += ((polygon.x * polygon.y) - (polygon.y * polygon.x));
j = i;
}
return fabs(result * double(0.5));
}
void intersect_line_to_line(double x3, double y3, double x4, double y4, double x1, double y1, double x2, double y2, double &ix, double &iy)
{
double dx1 = x2 - x1;
double dx2 = x4 - x3;
double dx3 = x1 - x3;
double dy1 = y2 - y1;
double dy2 = y1 - y3;
double dy3 = y4 - y3;
double ratio = dx1 * dy3 - dy1 * dx2;
if (ratio != 0.0)
{
ratio = (dy2 * dx2 - dx3 * dy3) / ratio;
ix = x1 + ratio * dx1;
iy = y1 + ratio * dy1;
}
else
{
if ((dx1 * -dy2) == (-dx3 * dy1))
{
ix = x3;
iy = y3;
}
else
{
ix = x4;
iy = y4;
}
}
}
bool intersect_segment_to_segment(double x1, double y1, double x2, double y2, double x3, double y3, double x4, double y4, double &ix, double &iy)
{
double ax = x2 - x1;
double bx = x3 - x4;
double lowerx;
double upperx;
double uppery;
double lowery;
if (ax < double(0.0))
{
lowerx = x2;
upperx = x1;
}
else
{
upperx = x2;
lowerx = x1;
}
if (bx > double(0.0))
{
if ((upperx < x4) || (x3 < lowerx))
return false;
}
else if ((upperx < x3) || (x4 < lowerx))
return false;
double ay = y2 - y1;
double by = y3 - y4;
if (ay < double(0.0))
{
lowery = y2;
uppery = y1;
}
else
{
uppery = y2;
lowery = y1;
}
if (by > double(0.0))
{
if ((uppery < y4) || (y3 < lowery))
return false;
}
else if ((uppery < y3) || (y4 < lowery))
return false;
double cx = x1 - x3;
double cy = y1 - y3;
double d= (by * cx) - (bx * cy);
double f= (ay * bx) - (ax * by);
if (f > double(0.0))
{
if ((d < double(0.0)) || (d > f))
return false;
}
else if ((d > double(0.0)) || (d < f))
return false;
double e = (ax * cy) - (ay * cx);
if (f > double(0.0))
{
if ((e < double(0.0)) || (e > f))
return false;
}
else if ((e > double(0.0)) || (e < f))
return false;
double ratio = (ax * -by) - (ay * -bx);
if (ratio != double(0.0))
{
ratio = ((cy * -bx) - (cx * -by)) / ratio;
ix = x1 + (ratio * ax);
iy = y1 + (ratio * ay);
}
else
{
if ((ax * -cy) == (-cx * ay))
{
ix = x3;
iy = y3;
}
else
{
ix = x4;
iy = y4;
}
}
return true;
}
是C语言程序吗？ 新手来学习一下，多谢分享 好像是C语言写的吧，楼主这些程序在什么环境下运行啊 如果有显卡直接调用opengl或D3D是不是比较方便一些. C语言程序啊 好东西，谢谢分享！
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