100 lines
2.6 KiB
Python
100 lines
2.6 KiB
Python
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#!/usr/bin/env python3
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class Triangle():
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#given segment
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def __init__(self,_a,_b,_c):
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self.a=_a
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self.b=_b
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self.c=_c
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def __repr__(self):
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return "Triangle:("+str(self.a)+","+str(self.b)+","+str(self.c)+")"
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# Center of gravity centered on #a
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# @return u how much to b
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# @return v how much in the c direction
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def barycentric(self,p):
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#How to use barycentric coordinates
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#http://www.blackpawn.com/texts/pointinpoly/default.html
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ca = self.c-self.a
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ba = self.b-self.a
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pa = p-self.a
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#Calculate dot product
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dotca = ca.dot(ca)
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dotcba = ca.dot(ba)
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dotcpa = ca.dot(pa)
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dotba = ba.dot(ba)
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dotbpa = ba.dot(pa)
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#Calculation of barycentric coordinates
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invDenom = 1 / (dotca * dotba - dotcba * dotcba);
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u = (dotba * dotcpa-dotcba*dotbpa)*invDenom
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v = (dotca * dotbpa - dotcba * dotcpa) * invDenom
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return u,v
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# Whether there is a point inside the triangle
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def isContain(self,p):
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u,v=self.barycentric(p)
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inkex.errormsg("\n u="+str(u)+" v="+str(v))
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If #u=v=0, the same point as the triangle point
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#Check if there is a point in the triangle
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return (u > 0) and (v > 0) and (u + v < 1)
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def toSVG(self):
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return str(self.a.x)+","+str(self.a.y)+","+str(self.b.x)+","+str(self.b.y)+","+str(self.c.x)+","+str(self.c.y)
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# Is the arrangement of vertices a, b, c clockwise?
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def isClockWise(self):
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circle=self.circumcircle()
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center=circle.center
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aTob=self.b-self.a
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aToc=self.c-self.a
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#Let's find the cross product
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cross=aTob.cross(aToc)
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inkex.errormsg(" cross"+str(cross))
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if(cross>0):
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return True
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return False#Counterclockwise
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def circumcircle(self):
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#Find the length of each side
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ab=(self.a-self.b).length()
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bc=(self.b-self.c).length()
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ca=(self.c-self.a).length()
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s=(ab+bc+ca)/2.0;
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area=math.sqrt(s*(s-ab)*(s-bc)*(s-ca));
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maxlength=0
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if(maxlength<ab):
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maxlength=ab;longestEdge=2
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if(maxlength<bc):
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maxlength=bc;longestEdge=0;
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if(maxlength<ca):
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maxlength=ca;longestEdge=1
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if longestEdge==0:
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ha=2*area/bc;
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angleB=math.asin(ha/ab);
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angleC=math.asin(ha/ca);
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angleA=math.pi-angleB-angleC;
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if longestEdge== 1:
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hb=2*area/ca;
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angleA=math.asin(hb/ab);
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angleC=math.asin(hb/bc);
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angleB=math.pi-angleC-angleA;
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if longestEdge== 2:
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hc=2*area/ab;
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angleB=math.asin(hc/bc);
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angleA=math.asin(hc/ca);
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angleC=math.pi-angleA-angleB;
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A = math.sin(2.0*angleA);
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B = math.sin(2.0*angleB);
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C = math.sin(2.0*angleC);
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center=Vertex((self.a.x * A + self.b.x * B + self.c.x * C) / (A+B+C),
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(self.a.y * A + self.b.y * B + self.c.y * C) / (A+B+C));
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rad=bc / math.sin(angleA) / 2.0
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return Circle(center,rad);
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