def getIntersection(self, entity, point):
"""
this function compute the snap intersection point
"""
returnVal = None
distance = None
if entity != None:
geoEntityFrom = entity.geoItem
entityList = self._scene.collidingItems(entity)
for ent in entityList:
if not isinstance(ent, BaseEntity):
continue
if isinstance(ent, BaseEntity):
intPoint = find_intersections(ent.geoItem, geoEntityFrom)
for tp in intPoint:
iPoint = Point(tp[0], tp[1])
if distance == None:
distance = iPoint.dist(point)
returnVal = iPoint
else:
spoolDist = iPoint.dist(point)
if distance > spoolDist:
distance = spoolDist
returnVal = iPoint
return returnVal
def GetTangentPoint(self,x,y,outx,outy):
"""
Get the tangent from an axternal point
args:
x,y is a point near the circle
xout,yout is a point far from the circle
return:
a tuple(x,y,x1,xy) that define the tangent line
"""
firstPoint=Point(x,y)
fromPoint=Point(outx,outy)
twoPointDistance=self.center.dist(fromPoint)
if(twoPointDistance<self.radius):
return None,None
originPoint=Point(0.0,0.0)
tanMod=math.sqrt(pow(twoPointDistance,2)-pow(self.radius,2))
tgAngle=math.asin(self.radius/twoPointDistance)
#Compute the x versor
xPoint=Point(1.0,0.0)
xVector=Vector(originPoint,xPoint)
twoPointVector=Vector(fromPoint,self.center)
rightAngle=twoPointVector.ang(xVector)
cx,cy=self.center.getCoords()
if(outy>cy): # stupid situation
rightAngle=-rightAngle
posAngle=rightAngle+tgAngle
negAngle=rightAngle-tgAngle
# Compute the Positive Tangent
xCord=math.cos(posAngle)
yCord=math.sin(posAngle)
dirPoint=Point(xCord,yCord) # Versor that point at the tangentPoint
ver=Vector(originPoint,dirPoint)
ver.mult(tanMod)
tangVectorPoint=ver.Point()
posPoint=Point(tangVectorPoint+(outx,outy))
# Compute the Negative Tangent
xCord=math.cos(negAngle)
yCord=math.sin(negAngle)
dirPoint=Point(xCord,yCord)#Versor that point at the tangentPoint
ver=Vector(originPoint,dirPoint)
ver.mult(tanMod)
tangVectorPoint=ver.point()
negPoint=Point(tangVectorPoint+(outx,outy))
if(firstPoint.dist(posPoint)<firstPoint.dist(negPoint)):
return posPoint.getCoords()
else:
return negPoint.getCoords()