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libgeometry: add ptincylinder and ptincone

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rodri 2024-10-14 12:04:35 +00:00
parent b6b5e569e9
commit 708ff097a6
3 changed files with 70 additions and 0 deletions
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2
sys/include/geometry.h
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@ -78,6 +78,8 @@ Point3 crossvec3(Point3, Point3);
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);

20
sys/man/2/geometry
View file

@ -90,6 +90,8 @@ double vec3len(Point3 v)
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 @@ to
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

48
sys/src/libgeometry/point.c
View file

@ -248,3 +248,51 @@ lineXsphere(Point3 *rp, Point3 p0, Point3 p1, Point3 c, double r, int isaray)
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;
}