Geometries

Geometries

Geometry entities are child elements of <visual> or <collision> elements.

# Import the element creator
from pcg_gazebo.parsers.urdf import create_urdf_element

Basic entities

Demonstration of the basic URDF elements that can be generated with and without the optional parameters.

Geometries

Box

# Default box
box = create_urdf_element('box')
print('Default box')
print(box)

print('Default box - as dict')
print(box.to_dict())

print('Default box - as URDF')
print(box.to_xml_as_str())

# Changing the size
box.size = [2, 3, 4]
print('Custom box')
print(box)

# Exporting 
# box.export_xml('/tmp/box.urdf')

Default box
<box size="0 0 0"/>

Default box - as dict
{'box': {'attributes': {'size': '0 0 0'}}}
Default box - as URDF
<box size="0 0 0"/>
Custom box
<box size="2 3 4"/>

Cylinder

# Default cylinder
cylinder = create_urdf_element('cylinder')
print('Default cylinder')
print(cylinder)

print('Default cylinder - as dict')
print(cylinder.to_dict())

print('Default cylinder - as URDF')
print(cylinder.to_xml_as_str())

# Changing the parameters
cylinder.radius = 2
cylinder.length = 3
print('Custom cylinder')
print(cylinder)

# Exporting 
# cylinder.export_xml('/tmp/cylinder.urdf')

Default cylinder
<cylinder length="0" radius="0"/>

Default cylinder - as dict
{'cylinder': {'attributes': {'radius': '0', 'length': '0'}}}
Default cylinder - as URDF
<cylinder length="0" radius="0"/>
Custom cylinder
<cylinder length="3" radius="2"/>

Sphere

# Default sphere
sphere = create_urdf_element('sphere')
print('Default sphere')
print(sphere)

print('Default sphere - as dict')
print(sphere.to_dict())

print('Default sphere - as URDF')
print(sphere.to_xml_as_str())

# Changing the parameters
sphere.radius = 2
print('Custom sphere')
print(sphere)

# Exporting 
# sphere.export_xml('/tmp/sphere.urdf')

Default sphere
<sphere radius="0"/>

Default sphere - as dict
{'sphere': {'attributes': {'radius': '0'}}}
Default sphere - as URDF
<sphere radius="0"/>
Custom sphere
<sphere radius="2"/>

Mesh

mesh = create_urdf_element('mesh')
print('Default mesh - with default parameters')
print(mesh)

print('Default mesh - as dict')
print(mesh.to_dict())

print('Default mesh - as URDF')
print(mesh.to_xml_as_str())

# Changing the parameters
mesh.filename = 'package://mesh.dae'
print('Custom mesh')
print(mesh)

# Exporting 
# mesh.export_xml('/tmp/mesh.urdf')

Default mesh - with default parameters
<mesh filename=""/>

Default mesh - as dict
{'mesh': {'attributes': {'filename': ''}}}
Default mesh - as URDF
<mesh filename=""/>
Custom mesh
<mesh filename="package://mesh.dae"/>

Creating a geometry entity

# Initially, the geometry is created with a <box/> element
geometry = create_urdf_element('geometry')
print(geometry)

<geometry>
  <box size="0 0 0"/>
</geometry>

# Creating a geometry for each of the basic forms
# The geometry entity has a separate mode for each possible geometry forms, since it cannot hold
# multiple geometries
# When a new geometry is set, the former one is deleted
print('All the geometry entity modes:')
print(geometry.get_modes())

geometry.box = box
print(geometry)

geometry.cylinder = cylinder
print(geometry)

geometry.sphere = sphere
print(geometry)

geometry.mesh = mesh
print(geometry)

All the geometry entity modes:
['box', 'cylinder', 'sphere', 'mesh']
<geometry>
  <box size="2 3 4"/>
</geometry>

<geometry>
  <cylinder length="3" radius="2"/>
</geometry>

<geometry>
  <sphere radius="2"/>
</geometry>

<geometry>
  <mesh filename="package://mesh.dae"/>
</geometry>