def bend(self, amount):
"""Bend the line to the right by a given distance."""
if amount == 0:
self.arcthrupoint = None
return self
middle = self.p1.midpoint(self.p2)
nx = (middle.y() - self.p1.y()) / abs(self.p1.distance(middle))
ny = (self.p1.x() - middle.x()) / abs(self.p1.distance(middle))
vx = middle.x() - self.p1.x()
vy = middle.y() - self.p1.y()
if (vx * ny - vy * nx) > 0:
nx *= -1
ny *= -1
arcpoint = Point(middle.x() + amount * nx, middle.y() + amount * ny)
if config.getOptions().VDEBUG:
FeynDiagram.currenDiagram.currentCanvas.stroke(
pyx.path.line(middle.x(), middle.y(), arcpoint.x(),
arcpoint.y()), [color.rgb.blue])
self.arcThru(arcpoint)
if config.getOptions().DEBUG:
print(self.getVisiblePath())
if config.getOptions().VDEBUG:
FeynDiagram.currenDiagram.currentCanvas.stroke(
self.getVisiblePath(), [color.rgb.blue])
return self
def fracpoint(self, frac):
"""
Get a new Point representing the point at the given fraction along
the fundamental line (i.e. no truncation or deformation).
TODO: Handle units properly.
"""
p = self.getPath() ## no truncation or deformation
x, y = p.at(p.begin() + frac * p.arclen())
return Point(x/defunit, y/defunit)
def arcThru(self, arcpoint = None, x = None, y = None):
"""Set the point through which this line will arc. Either pass a Point
or set x, y as floats."""
if arcpoint is not None:
self.arcthrupoint = arcpoint
elif x is not None and y is not None:
self.arcthrupoint = Point(x, y)
else:
raise Exception("Tried to set an arcpoint with invalid arguments")
return self
def getPath(self):
"""Get the path taken by this line."""
if self.arcthrupoint is None:
## This is a simple straight line
return pyx.path.path( pyx.path.moveto( *(self.p1.getXY()) ),
pyx.path.lineto( *(self.p2.getXY()) ) )
elif (self.p1.x() == self.p2.x() and self.p1.y() == self.p2.y()):
## This is a tadpole-type loop and needs special care;
## We shall assume that the arcthrupoint is meant to be
## the antipode of the basepoint
arccenter = self.p1.midpoint(self.arcthrupoint)
arcradius = self.p1.distance(self.arcthrupoint) / 2.0
## TODO Why does a circle work and an arc doesn't?
cargs = (arccenter.x(), arccenter.y(), arcradius)
circle = pyx.path.circle(*cargs)
line = pyx.path.line( self.p1.x(), self.p1.y(), arccenter.x(), arccenter.y())
if config.getOptions().VDEBUG:
FeynDiagram.currenDiagram.currentCanvas.stroke(line, [color.rgb.green])
ass, bs = circle.intersect(line)
subpaths = circle.split(ass[0])
cpath = subpaths[0]
return cpath
## or, with an arc...
arcangle1 = arccenter.arg(self.p1)
arcangle2 = arccenter.arg(self.p1) + 360
arcargs = (arccenter.x(), arccenter.y(), arcradius, arcangle1, arcangle2)
return pyx.path.path( pyx.path.arc(*arcargs) )
else:
n13, n23 = None, None
## Work out line gradients
try:
n13 = (self.p1.y() - self.arcthrupoint.y()) / (self.p1.x() - self.arcthrupoint.x())
except ZeroDivisionError:
if config.getOptions().DEBUG:
print("Grad 1 diverges")
n13 = 1e100
try:
n23 = (self.p2.y() - self.arcthrupoint.y()) / (self.p2.x() - self.arcthrupoint.x())
except ZeroDivisionError:
if config.getOptions().DEBUG:
print("Grad 2 diverges")
n23 = 1e100
## If gradients match,
## then we have a straight line, so bypass the complexity
if n13 == n23:
return pyx.path.path( pyx.path.moveto(*(self.p1.getXY())),
pyx.path.lineto(*(self.p2.getXY())) )
## Otherwise work out conjugate gradients and midpoints
m13, m23 = None, None
try:
m13 = -1.0 / n13
except ZeroDivisionError:
m13 = 1e100
try:
m23 = -1.0 / n23
except ZeroDivisionError:
m23 = 1e100
mid13 = self.p1.midpoint(self.arcthrupoint)
mid23 = self.p2.midpoint(self.arcthrupoint)
## Line y-intercepts
c13 = mid13.y() - m13 * mid13.x()
c23 = mid23.y() - m23 * mid23.x()
## Find the centre of the arc
xcenter = - (c23 - c13) / (m23 - m13)
ycenter = m13 * xcenter + c13
arccenter = Point(xcenter, ycenter)
## Get the angles required for drawing the arc
arcradius = arccenter.distance(self.arcthrupoint)
arcangle1 = arccenter.arg(self.p1)
arcangle2 = arccenter.arg(self.p2)
arcangle3 = arccenter.arg(self.arcthrupoint)
arcargs = (arccenter.x(), arccenter.y(), arcradius, arcangle1, arcangle2)
if config.getOptions().DEBUG and arcangle1 == arcangle2:
print("Arc angles are the same - not drawing anything")
## Calculate cross product to determine direction of arc
vec12 = [self.p2.x()-self.p1.x(), self.p2.y()-self.p1.y(), 0.0]
vec13 = [self.arcthrupoint.x()-self.p1.x(), self.arcthrupoint.y()-self.p1.y(), 0.0]
crossproductZcoord = vec12[0]*vec13[1] - vec12[1]*vec13[0]
if crossproductZcoord < 0:
return pyx.path.path( pyx.path.moveto(*(self.p1.getXY())),
pyx.path.arc(*arcargs))
else:
return pyx.path.path( pyx.path.moveto(*(self.p1.getXY())),
pyx.path.arcn(*arcargs))
bCOLOR = [BLUE]
tCOLOR = [RED]
dCOLOR = [RED]
ZCOLOR = [RED]
pCOLOR = [FORESTGREEN]
eCOLOR = [BLUE]
gCOLOR = [VIOLET]
#-------------------------------------------------------------------------
# tZq production (5FS) - WWZ vertex
fd = FeynDiagram()
# l1 = Label('Lowest Order', x=0, y=2)
pntIn = []
pntOut = []
pntIn.append(Point(-3, +1.5))
pntIn.append(Point(-3, -1.5))
pntOut.append(Point(+3, +1.5))
pntOut.append(Point(+3, -1.5))
vtx = []
vtx.append(Vertex(0, +1.5, mark=CIRCLE, fill=[RED]))
vtx.append(Vertex(0, -1.5, mark=CIRCLE, fill=[RED]))
# Add Z boson on various lines
vtx.append(Vertex(0.5, 0.0, mark=CIRCLE, fill=[RED]))
pntOut.append(Point(+3, 0.0))
draw_fermion(pntIn[0], vtx[0], uCOLOR, r'\Pqu', displacement=+0.2)
draw_fermion(vtx[0], pntOut[0], dCOLOR, r'\Pqd', displacement=+0.2)
draw_boson(vtx[2], vtx[0], pCOLOR, r'\PW')
