def checkDef(pd):
"""Check the polygon definition for invalid vertices, etc.
Return: True if valid, False if invalid
"""
# if pd.vertexCount < 3 or pd.vertexCount > box2d.b2_maxPolygonVertices:
#raise ValueError, "Invalid vertexCount"
threshold = FLT_EPSILON * FLT_EPSILON
verts = pd.getVertices_b2Vec2()
normals = []
v0 = verts[0]
for i in range(pd.vertexCount):
if i == pd.vertexCount - 1:
v1 = verts[0]
else:
v1 = verts[i + 1]
edge = v1 - v0
# if edge.LengthSquared() < threshold:
# raise ValueError, "edge.LengthSquared < FLT_EPSILON**2"
normals.append(box2d.b2Cross(edge, 1.0))
normals[-1].Normalize()
v0 = v1
centroid = ComputeCentroid(pd)
d = box2d.b2Vec2()
for i in range(pd.vertexCount):
i1 = i - 1
if i1 < 0: i1 = pd.vertexCount - 1
i2 = i
n1 = normals[i1]
n2 = normals[i2]
v = verts[i] - centroid
d.x = box2d.b2Dot(n1, v) - box2d.b2_toiSlop
d.y = box2d.b2Dot(n2, v) - box2d.b2_toiSlop
# Shifting the edge inward by b2_toiSlop should
# not cause the plane to pass the centroid.
# Your shape has a radius/extent less than b2_toiSlop.
# if d.x < 0.0 or d.y <= 0.0:
# raise ValueError, "Your shape has a radius/extent less than b2_toiSlop."
A = box2d.b2Mat22()
A.col1.x = n1.x
A.col2.x = n1.y
A.col1.y = n2.x
A.col2.y = n2.y
#coreVertices[i] = A.Solve(d) + m_centroid
return True
def checkDef(pd):
"""Check the polygon definition for invalid vertices, etc.
Return: True if valid, False if invalid
"""
# if pd.vertexCount < 3 or pd.vertexCount > box2d.b2_maxPolygonVertices:
# raise ValueError, "Invalid vertexCount"
threshold = FLT_EPSILON * FLT_EPSILON
verts = pd.getVertices_b2Vec2()
normals = []
v0 = verts[0]
for i in range(pd.vertexCount):
if i == pd.vertexCount - 1:
v1 = verts[0]
else:
v1 = verts[i + 1]
edge = v1 - v0
# if edge.LengthSquared() < threshold:
# raise ValueError, "edge.LengthSquared < FLT_EPSILON**2"
normals.append(box2d.b2Cross(edge, 1.0))
normals[-1].Normalize()
v0 = v1
centroid = ComputeCentroid(pd)
d = box2d.b2Vec2()
for i in range(pd.vertexCount):
i1 = i - 1
if i1 < 0:
i1 = pd.vertexCount - 1
i2 = i
n1 = normals[i1]
n2 = normals[i2]
v = verts[i] - centroid
d.x = box2d.b2Dot(n1, v) - box2d.b2_toiSlop
d.y = box2d.b2Dot(n2, v) - box2d.b2_toiSlop
# Shifting the edge inward by b2_toiSlop should
# not cause the plane to pass the centroid.
# Your shape has a radius/extent less than b2_toiSlop.
# if d.x < 0.0 or d.y <= 0.0:
# raise ValueError, "Your shape has a radius/extent less than b2_toiSlop."
A = box2d.b2Mat22()
A.col1.x = n1.x
A.col2.x = n1.y
A.col1.y = n2.x
A.col2.y = n2.y
# coreVertices[i] = A.Solve(d) + m_centroid
return True
def ComputeCentroid(pd):
count = pd.vertexCount
if count < 3:
return False
c = box2d.b2Vec2(0, 0)
area = 0.0
# pRef is the reference point for forming triangles.
# It's location doesn't change the result (except for rounding error).
pRef = box2d.b2Vec2(0.0, 0.0)
inv3 = 1.0 / 3.0
for i in range(count):
# Triangle vertices.
p1 = pRef
p2 = pd.getVertex(i)
if i + 1 < count:
p3 = pd.getVertex(i + 1)
else:
p3 = pd.getVertex(0)
e1 = p2 - p1
e2 = p3 - p1
D = box2d.b2Cross(e1, e2)
triangleArea = 0.5 * D
area += triangleArea
# Area weighted centroid
c += triangleArea * inv3 * (p1 + p2 + p3)
# Centroid
# if area < FLT_EPSILON:
#raise ValueError, "ComputeCentroid: area < FLT_EPSILON"
return c / area
def ComputeCentroid(pd):
count = pd.vertexCount
if count < 3:
return False
c = box2d.b2Vec2(0, 0)
area = 0.0
# pRef is the reference point for forming triangles.
# It's location doesn't change the result (except for rounding error).
pRef = box2d.b2Vec2(0.0, 0.0)
inv3 = 1.0 / 3.0
for i in range(count):
# Triangle vertices.
p1 = pRef
p2 = pd.getVertex(i)
if i + 1 < count:
p3 = pd.getVertex(i + 1)
else:
p3 = pd.getVertex(0)
e1 = p2 - p1
e2 = p3 - p1
D = box2d.b2Cross(e1, e2)
triangleArea = 0.5 * D
area += triangleArea
# Area weighted centroid
c += triangleArea * inv3 * (p1 + p2 + p3)
# Centroid
# if area < FLT_EPSILON:
# raise ValueError, "ComputeCentroid: area < FLT_EPSILON"
return c / area
