First Tutorial - Falling cube
Download as PPTX, PDF0 likes480 views
This tutorial document provides instructions for setting up and running a falling cube simulation using the Sofa physics engine. It describes how to install Sofa Modeler, add a cube node to the scene graph, load a cube mesh, define mechanical properties like mass and degrees of freedom, add solvers to simulate physics, add a visual node and model to display the cube, map the graphics to mechanics, and run the simulation. The tutorial is intended to demonstrate the basic workflow and components for building a simple falling cube simulation in Sofa Modeler.
First Tutorial - Falling cube
- 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 Muhammad Muddassir Malik 2
- 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. Muhammad Muddassir Malik 3
- 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. Muhammad Muddassir Malik 4
- 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) Muhammad Muddassir Malik 5
- 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. Muhammad Muddassir Malik 6
- 7. Adding a node Muhammad Muddassir Malik 7
- 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. Muhammad Muddassir Malik 8
- 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. Muhammad Muddassir Malik 9
- 10. Mesh topology Muhammad Muddassir Malik 10
- 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). Muhammad Muddassir Malik 11
- 12. Loading the Mesh Muhammad Muddassir Malik 12
- 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. Muhammad Muddassir Malik 13
- 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. Muhammad Muddassir Malik 14
- 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. Muhammad Muddassir Malik 15
- 16. Adding Mass to the object Muhammad Muddassir Malik 16
- 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. Muhammad Muddassir Malik 17
- 18. Adding Solvers Muhammad Muddassir Malik 18
- 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. Muhammad Muddassir Malik 19
- 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. Muhammad Muddassir Malik 20
- 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. Muhammad Muddassir Malik 22
- 23. Adding Barycentric Mapping Muhammad Muddassir Malik 23
- 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. Muhammad Muddassir Malik 24
- 25. Animate • It will open up another GUI window. • There you have to click the animate button to run the animation. Muhammad Muddassir Malik 25