def strang_mesh(filename):
"""Read Strang generated mesh.
"""
from math import pi
from anuga.utilities.numerical_tools import anglediff
fid = open(filename)
points = [] # List of x, y coordinates
triangles = [] # List of vertex ids as listed in the file
for line in fid.readlines():
fields = line.split()
if len(fields) == 2:
# we are reading vertex coordinates
points.append([float(fields[0]), float(fields[1])])
elif len(fields) == 3:
# we are reading triangle point id's (format ae+b)
triangles.append([
int(float(fields[0])) - 1,
int(float(fields[1])) - 1,
int(float(fields[2])) - 1
])
else:
raise Excetion('wrong format in %s' % filename)
elements = [] #Final list of elements
for t in triangles:
#Get vertex coordinates
v0 = t[0]
v1 = t[1]
v2 = t[2]
x0 = points[v0][0]
y0 = points[v0][1]
x1 = points[v1][0]
y1 = points[v1][1]
x2 = points[v2][0]
y2 = points[v2][1]
#Check that points are arranged in counter clock-wise order
vec0 = [x1 - x0, y1 - y0]
vec1 = [x2 - x1, y2 - y1]
vec2 = [x0 - x2, y0 - y2]
a0 = anglediff(vec1, vec0)
a1 = anglediff(vec2, vec1)
a2 = anglediff(vec0, vec2)
if a0 < pi and a1 < pi and a2 < pi:
elements.append([v0, v1, v2])
else:
elements.append([v0, v2, v1])
return points, elements
def strang_mesh(filename):
"""Read Strang generated mesh.
"""
from math import pi
from anuga.utilities.numerical_tools import anglediff
fid = open(filename)
points = [] # List of x, y coordinates
triangles = [] # List of vertex ids as listed in the file
for line in fid.readlines():
fields = line.split()
if len(fields) == 2:
# we are reading vertex coordinates
points.append([float(fields[0]), float(fields[1])])
elif len(fields) == 3:
# we are reading triangle point id's (format ae+b)
triangles.append([int(float(fields[0]))-1,
int(float(fields[1]))-1,
int(float(fields[2]))-1])
else:
raise Excetion('wrong format in %s' % filename)
elements = [] #Final list of elements
for t in triangles:
#Get vertex coordinates
v0 = t[0]
v1 = t[1]
v2 = t[2]
x0 = points[v0][0]
y0 = points[v0][1]
x1 = points[v1][0]
y1 = points[v1][1]
x2 = points[v2][0]
y2 = points[v2][1]
#Check that points are arranged in counter clock-wise order
vec0 = [x1-x0, y1-y0]
vec1 = [x2-x1, y2-y1]
vec2 = [x0-x2, y0-y2]
a0 = anglediff(vec1, vec0)
a1 = anglediff(vec2, vec1)
a2 = anglediff(vec0, vec2)
if a0 < pi and a1 < pi and a2 < pi:
elements.append([v0, v1, v2])
else:
elements.append([v0, v2, v1])
return points, elements
def from_polyfile(name):
"""Read mesh from .poly file, an obj like file format
listing first vertex coordinates and then connectivity
"""
from anuga.utilities.numerical_tools import anglediff
from math import pi
import os.path
root, ext = os.path.splitext(name)
if ext == 'poly':
filename = name
else:
filename = name + '.poly'
fid = open(filename)
points = [] #x, y
values = [] #z
##vertex_values = [] #Repeated z
triangles = [] #v0, v1, v2
lines = fid.readlines()
keyword = lines[0].strip()
msg = 'First line in .poly file must contain the keyword: POINTS'
assert keyword == 'POINTS', msg
offending = 0
i = 1
while keyword == 'POINTS':
line = lines[i].strip()
i += 1
if line == 'POLYS':
keyword = line
break
fields = line.split(':')
assert int(fields[0]) == i-1, 'Point indices not consecutive'
#Split the three floats
xyz = fields[1].split()
x = float(xyz[0])
y = float(xyz[1])
z = float(xyz[2])
points.append([x, y])
values.append(z)
k = i
while keyword == 'POLYS':
line = lines[i].strip()
i += 1
if line == 'END':
keyword = line
break
fields = line.split(':')
assert int(fields[0]) == i-k, 'Poly indices not consecutive'
#Split the three indices
vvv = fields[1].split()
i0 = int(vvv[0])-1
i1 = int(vvv[1])-1
i2 = int(vvv[2])-1
#Check for and exclude degenerate areas
x0 = points[i0][0]
y0 = points[i0][1]
x1 = points[i1][0]
y1 = points[i1][1]
x2 = points[i2][0]
y2 = points[i2][1]
area = old_div(abs((x1*y0-x0*y1)+(x2*y1-x1*y2)+(x0*y2-x2*y0)),2)
if area > 0:
#Ensure that points are arranged in counter clock-wise order
v0 = [x1-x0, y1-y0]
v1 = [x2-x1, y2-y1]
v2 = [x0-x2, y0-y2]
a0 = anglediff(v1, v0)
a1 = anglediff(v2, v1)
a2 = anglediff(v0, v2)
if a0 < pi and a1 < pi and a2 < pi:
#all is well
j0 = i0
j1 = i1
j2 = i2
else:
#Swap two vertices
j0 = i1
j1 = i0
j2 = i2
triangles.append([j0, j1, j2])
##vertex_values.append([values[j0], values[j1], values[j2]])
else:
offending +=1
log.critical('Removed %d offending triangles out of %d'
% (offending, len(lines)))
return points, triangles, values
def from_polyfile(name):
"""Read mesh from .poly file, an obj like file format
listing first vertex coordinates and then connectivity
"""
from anuga.utilities.numerical_tools import anglediff
from math import pi
import os.path
root, ext = os.path.splitext(name)
if ext == 'poly':
filename = name
else:
filename = name + '.poly'
fid = open(filename)
points = [] #x, y
values = [] #z
##vertex_values = [] #Repeated z
triangles = [] #v0, v1, v2
lines = fid.readlines()
keyword = lines[0].strip()
msg = 'First line in .poly file must contain the keyword: POINTS'
assert keyword == 'POINTS', msg
offending = 0
i = 1
while keyword == 'POINTS':
line = lines[i].strip()
i += 1
if line == 'POLYS':
keyword = line
break
fields = line.split(':')
assert int(fields[0]) == i-1, 'Point indices not consecutive'
#Split the three floats
xyz = fields[1].split()
x = float(xyz[0])
y = float(xyz[1])
z = float(xyz[2])
points.append([x, y])
values.append(z)
k = i
while keyword == 'POLYS':
line = lines[i].strip()
i += 1
if line == 'END':
keyword = line
break
fields = line.split(':')
assert int(fields[0]) == i-k, 'Poly indices not consecutive'
#Split the three indices
vvv = fields[1].split()
i0 = int(vvv[0])-1
i1 = int(vvv[1])-1
i2 = int(vvv[2])-1
#Check for and exclude degenerate areas
x0 = points[i0][0]
y0 = points[i0][1]
x1 = points[i1][0]
y1 = points[i1][1]
x2 = points[i2][0]
y2 = points[i2][1]
area = abs((x1*y0-x0*y1)+(x2*y1-x1*y2)+(x0*y2-x2*y0))/2
if area > 0:
#Ensure that points are arranged in counter clock-wise order
v0 = [x1-x0, y1-y0]
v1 = [x2-x1, y2-y1]
v2 = [x0-x2, y0-y2]
a0 = anglediff(v1, v0)
a1 = anglediff(v2, v1)
a2 = anglediff(v0, v2)
if a0 < pi and a1 < pi and a2 < pi:
#all is well
j0 = i0
j1 = i1
j2 = i2
else:
#Swap two vertices
j0 = i1
j1 = i0
j2 = i2
triangles.append([j0, j1, j2])
##vertex_values.append([values[j0], values[j1], values[j2]])
else:
offending +=1
log.critical('Removed %d offending triangles out of %d'
% (offending, len(lines)))
return points, triangles, values
