Geometries

Geometries

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

# Import the element creator
from pcg_gazebo.parsers.sdf import create_sdf_element

Basic entities

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

Geometries

Box

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

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

print('Default box - as SDF')
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.sdf')

Default box
<box>
  <size>0 0 0</size>
</box>

Default box - as dict
{'box': {'size': {'value': [0, 0, 0]}}}
Default box - as SDF
<box><size>0 0 0</size></box>
Custom box
<box>
  <size>2 3 4</size>
</box>

Cylinder

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

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

print('Default cylinder - as SDF')
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.sdf')

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

Default cylinder - as dict
{'cylinder': {'length': {'value': 0}, 'radius': {'value': 0}}}
Default cylinder - as SDF
<cylinder><length>0</length><radius>0</radius></cylinder>
Custom cylinder
<cylinder>
  <length>3.0</length>
  <radius>2.0</radius>
</cylinder>

Sphere

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

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

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

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

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

Default sphere
<sphere>
  <radius>0</radius>
</sphere>

Default sphere - as dict
{'sphere': {'radius': {'value': 0}}}
Default sphere - as SDF
<sphere><radius>0</radius></sphere>
Custom sphere
<sphere>
  <radius>2.0</radius>
</sphere>

Plane

# Default plane
plane = create_sdf_element('plane')
print('Default plane')
print(plane)

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

print('Default plane - as SDF')
print(plane.to_xml_as_str())

# Changing the parameters
# Length of each side of the plane
plane.size = [10, 10]
# Normal direction of the plane
plane.normal = [1, 0, 0]
print('Custom plane')
print(plane)

# Exporting 
# plane.export_xml('/tmp/plane.sdf')

Default plane
<plane>
  <size>0 0</size>
  <normal>0 0 1</normal>
</plane>

Default plane - as dict
{'plane': {'size': {'value': [0, 0]}, 'normal': {'value': [0, 0, 1]}}}
Default plane - as SDF
<plane><size>0 0</size><normal>0 0 1</normal></plane>
Custom plane
<plane>
  <size>10 10</size>
  <normal>1 0 0</normal>
</plane>

Image

A grayscale image can be used to extrude a set of boxes

# Default image
image = create_sdf_element('image')
print('Default image')
print(image)

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

print('Default image - as SDF')
print(image.to_xml_as_str())

# Height of the extruded boxes
image.height = 10
# The amount of error in the model
image.granularity = 1
# Grayscale threshold
image.threshold = 100
# Scaling factor applied to the image
image.scale = [2]
# URI of the grayscale image
image.uri = 'filename'

print('Custom image')
print(image)

# Exporting 
# image.export_xml('/tmp/image.sdf')

Default image
<image>
  <granularity>1</granularity>
  <height>1</height>
  <scale>1</scale>
  <uri></uri>
  <threshold>0</threshold>
</image>

Default image - as dict
{'image': {'granularity': {'value': 1}, 'height': {'value': 1}, 'scale': {'value': [1]}, 'uri': {'value': ''}, 'threshold': {'value': 0}}}
Default image - as SDF
<image><granularity>1</granularity><height>1</height><scale>1</scale><uri></uri><threshold>0</threshold></image>
Custom image
<image>
  <granularity>1</granularity>
  <height>10.0</height>
  <scale>2</scale>
  <uri>filename</uri>
  <threshold>100.0</threshold>
</image>

Mesh

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

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

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

Default mesh - with default parameters
<mesh>
  <scale>1 1 1</scale>
  <uri></uri>
</mesh>

Default mesh - as dict
{'mesh': {'scale': {'value': [1, 1, 1]}, 'uri': {'value': ''}}}
Default mesh - as SDF
<mesh><scale>1 1 1</scale><uri></uri></mesh>

print('Mesh with optional parameters')
mesh.reset(with_optional_elements=True)
print(mesh)

# Name of the submesh under the parent mesh
mesh.submesh.name = 'submesh.stl'
# Set to true to center the vertices of the submesh at (0, 0, 0)
mesh.submesh.center = True
# Scaling factor of the mesh
mesh.scale = [2, 1, 1]
# URI of the mesh
mesh.uri = 'file://mesh.stl'

print('Custom mesh')
print(mesh)

Mesh with optional parameters
<mesh>
  <scale>1 1 1</scale>
  <uri></uri>
  <submesh>
    <center>0</center>
    <name>none</name>
  </submesh>
</mesh>

Custom mesh
<mesh>
  <scale>2 1 1</scale>
  <uri>file://mesh.stl</uri>
  <submesh>
    <center>1</center>
    <name>submesh.stl</name>
  </submesh>
</mesh>

Polyline

polyline = create_sdf_element('polyline')
print('Default polyline - with default parameters')
print(polyline)

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

print('Default polyline - as SDF')
print(polyline.to_xml_as_str())

Default polyline - with default parameters
<polyline>
  <height>1</height>
</polyline>

Default polyline - as dict
{'polyline': {'height': {'value': 1}}}
Default polyline - as SDF
<polyline><height>1</height></polyline>

print('Polyline with optional parameters')
polyline.reset(with_optional_elements=True)
print(polyline)

# Set new height
polyline.height = 2.3
# Customize point
polyline.points[0].value = [2.3, 4.5]
# Add new point
polyline.add_point()
# Set the coordinates of new point
polyline.points[1].value = [3.7, 10.1]

print('Custom polyline')
print(polyline)

Polyline with optional parameters
<polyline>
  <point>0 0</point>
  <height>1</height>
</polyline>

Custom polyline
<polyline>
  <point>2.3 4.5</point>
  <point>3.7 10.1</point>
  <height>2.3</height>
</polyline>

Creating a geometry entity

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

<geometry>
  <empty></empty>
</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.plane = plane
print(geometry)

geometry.image = image
print(geometry)

geometry.mesh = mesh
print(geometry)

geometry.polyline = polyline
print(geometry)

All the geometry entity modes:
['empty', 'box', 'image', 'cylinder', 'sphere', 'plane', 'mesh', 'polyline']
<geometry>
  <box>
    <size>2 3 4</size>
  </box>
</geometry>

<geometry>
  <cylinder>
    <length>3.0</length>
    <radius>2.0</radius>
  </cylinder>
</geometry>

<geometry>
  <sphere>
    <radius>2.0</radius>
  </sphere>
</geometry>

<geometry>
  <plane>
    <size>10 10</size>
    <normal>1 0 0</normal>
  </plane>
</geometry>

<geometry>
  <image>
    <granularity>1</granularity>
    <height>10.0</height>
    <scale>2</scale>
    <uri>filename</uri>
    <threshold>100.0</threshold>
  </image>
</geometry>

<geometry>
  <mesh>
    <scale>2 1 1</scale>
    <uri>file://mesh.stl</uri>
    <submesh>
      <center>1</center>
      <name>submesh.stl</name>
    </submesh>
  </mesh>
</geometry>

<geometry>
  <polyline>
    <height>2.3</height>
    <point>2.3 4.5</point>
    <point>3.7 10.1</point>
  </polyline>
</geometry>