1. Tutorial Falling Cube
School of Electrical Engineering & Computer Science,
1
National University of Sciences & Technology, Pakistan
2. Run Sofa Modeler
• After installing sofa
• Go to the bin folder at installed location and double
click the Modeler
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3. Modeler
• After double clicking a Modeler a GUI window will
open up as shown below, with sofa components on
its left side and scene graph on its right.
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4. • There you will see root node already added.
– This node will control the global behavior of the
simulation.
– Majority of them are used to control the Collisions and
the responses between two or more objects during the
simulation.
• In our current exercise there is only one object so all of them
are not needed.
– All new nodes will be added under it and consequently
properties added to it will effect upon all other nodes.
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5. Deleting the unwanted nodes
• Delete all of the already placed properties root node by
selecting them and pressing the delete button (as they are
not required in our current exercise)
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6. Adding a node
• Then you have to add a node under whom whole
properties for a physical entity is going to be placed.
• For this you have to drag and drop GNode (placed
almost at left bottom of the Modeler under Sofa
Components) on Root node.
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8. Name the node
• To name the node double click on the node and
overwrite your desired name in object name blank
of property 1/2 tab. In this example we will name it
cube and then press the ok button.
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9. Mesh topology
• First of all to define and/or load the topology our
object’s mesh we have to add the MeshTopology
component.
• MeshToplogy define the topology and the relation
of one vertices with the other.
• Drag and Drop MeshTopology (lying in Topology
drop down of the sofa components) on the cube
node.
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11. Loading the Mesh
• Now we need to load and link the mesh of our object.
• Three easy ways to link and/or load the mesh with the topology are
– Load the mesh with in MeshTopolgy object.(practiced in this
exercise)
– Link the already Loaded Mesh (loaded through a loader e.g.
MeshObjLoader)
– Define the position of vertices in the mechanical object.
• To load the mesh file double click the MeshTopolgy Object and it will
open up a new Window.
• In Property 1/3, under file topology Click on the three dots like … in
front filename of the object and browse it to the location of your
intended object file (which is C:sofasharemeshcube.obj in our
current case).
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13. Mechanical state
• To define the mechanical properties and degree of
freedom you will have to add mechanicalObject.
– Here in Mechanical state of Rigid type object can only
act in a non-deformable way.
– While Vec3d type objects could act in both deformable
and non-deformable way.
– LaparoscopicRigid3 act same as Rigid type but with a
pivot in its center.
– Here 3d means three dimensional degrees of freedom
with precision of double and 3f means 3 dimensional
degree of freedom with precision of float.
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14. Adding MechanicalObject
• Click Mechanical State to open the drop down
– there you will find another drop down on the right side
• click to open that dropdown and select Vec3d from it
• Drag and drop MechanicalObject with Vec3d option
on the node present in the scene graph.
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15. Adding Mass to the object
• To define the mass of the object you have to add a
Mass component.
• Click on the Mass option (Just above Mechanical State)
in sofa components to have a look at the available mass
options in a drop down form.
• Select the Uniform Mass (simplest) of Vec3d for the
current exercise others will be used in relatively
complex type of exercises.
– Make sure it is of same type as of MechanicalObject which is
Vec3d in our current case.
• Drag and drop it on the cube node.
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17. Adding Solvers
• Now to solve all of the equations running behind the
intended simulation we have to add some
mathematical solver.
• For the instance you will have to add an ode solver
followed by a linear solver for our current exercise.
• Resultant of our ODE solver are the Linear equations
which are further efficiently solved by Linear Solver.
• For that you will have to drag and drop
EulerImplicitSolver from ode solver and CGLinearSolver
from Linear Solver.
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19. Visual node
• Afterwards we will put another GNode in our cube
Node to handle the graphical display.
• For that we will again drag and drop GNode on cube
node and name it cubeVisual.
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20. Visual Model
• We will now have to place a graphical display
modeler in the node.
• For that we will drag and drop the OglModel from
the VisualModel dropdown.
• In the property 2/4 of OglModel we will browse file
mesh the location of the intended show model
which is C:sofasharemeshcube.obj in our
current case.
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22. Mapping
• Now to map our graphical model on the mechanical
object we will use a mapping function.
• For this purpose you will have to drag and drop
BarycentricMapping from the mapping dropdown
of the sofa component to the Visual Node.
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24. Run sofa
• Now you are done with your development of first
exercise i.e. falling cube due to gravitational force.
• Click the run in sofa button, lying on the to middle
of the modeler screen.
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25. Animate
• It will open up another GUI window.
• There you have to click the animate button to run
the animation.
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