ref: 708ff097a62bbc65d7ba33df4883beb48c51fb86
parent: b6b5e569e983e17c65222d9ce09351daf5541be0
author: rodri <rgl@antares-labs.eu>
date: Mon Oct 14 08:04:35 EDT 2024
libgeometry: add ptincylinder and ptincone
--- a/sys/include/geometry.h
+++ b/sys/include/geometry.h
@@ -78,6 +78,8 @@
double vec3len(Point3);
Point3 normvec3(Point3);
int lineXsphere(Point3*, Point3, Point3, Point3, double, int);
+int ptincylinder(Point3, Point3, Point3, double);
+int ptincone(Point3, Point3, Point3, double);
/* Matrix */
void identity(Matrix);
--- a/sys/man/2/geometry
+++ b/sys/man/2/geometry
@@ -90,6 +90,8 @@
Point3 normvec3(Point3 v)
int lineXsphere(Point3 *rp, Point3 p0, Point3 p1,
Point3 c, double rad, int isaray)
+int ptincylinder(Point3 p, Point3 p0, Point3 p1, double r)
+int ptincone(Point3 p, Point3 p0, Point3 p1, double br)
.PB
/* Matrix */
void identity(Matrix m)
@@ -389,6 +391,24 @@
The function returns the number of intersections (up to two) and, if
.I rp
is not nil, it is filled with the resulting points.
+.TP
+.B ptincylinder(\fIp\fP,\fIp0\fP,\fIp1\fP,\fIr\fP)
+Tests if the point
+.I p
+is inside a cylinder with an axis defined by the line between
+.I p0
+and
+.IR p1 ,
+and a radius r.
+.TP
+.B ptincone(\fIp\fP,\fIp0\fP,\fIp1\fP,\fIbr\fP)
+Tests if the point
+.I p
+is inside a cone with its apex at
+.I p0
+and its base centered at
+.IR p1 ,
+with a radius of br.
.SS Matrices
.TP
Name
--- a/sys/src/libgeometry/point.c
+++ b/sys/src/libgeometry/point.c
@@ -248,3 +248,51 @@
return 2;
}
}
+
+/*
+ * p is the point to test
+ * p0 and p1 are the centers of the circles at each end of the cylinder
+ * r is the radius of these circles
+ */
+int
+ptincylinder(Point3 p, Point3 p0, Point3 p1, double r)
+{+ Point3 p01, p0p, p1p;
+ double h;
+
+ p01 = subpt3(p1, p0);
+ p0p = subpt3(p, p0);
+ p1p = subpt3(p, p1);
+ h = vec3len(p01);
+
+ if(h == 0)
+ return 0;
+
+ return dotvec3(p0p, p01) >= 0 &&
+ dotvec3(p1p, p01) <= 0 &&
+ vec3len(crossvec3(p0p, p01))/h <= r;
+}
+
+/*
+ * p is the point to test
+ * p0 is the apex
+ * p1 is the center of the base
+ * br is the radius of the base
+ */
+int
+ptincone(Point3 p, Point3 p0, Point3 p1, double br)
+{+ Point3 p01, p0p;
+ double h, d, r;
+
+ p01 = subpt3(p1, p0);
+ p0p = subpt3(p, p0);
+ h = vec3len(p01);
+ d = dotvec3(p0p, normvec3(p01));
+
+ if(h == 0 || d < 0 || d > h)
+ return 0;
+
+ r = d/h * br;
+ return vec3len(crossvec3(p0p, p01))/h <= r;
+}
--
⑨