Escritos por Will Pickering en los foros Hash Inc.

A:M SimCloth

SimCloth is a Polygon modifier. You need to apply that modifier to all the objects in the scene that take part in the cloth simulation. That includes not only the cloth objects themselves, but also all collision objects.
To add a new Polygon Modifier, right-click on your object in the choreography, from the popup menu, choose Add Polygon modifier->SimCloth.

SimCloth properties

• Object type - this property lets you choose the role of the object in the simulation:
• Deflector - deflectors are not affected by the SimCloth modifier, but they influence dynamic (cloth and rigid body) objects. SimCloth tries to keep all dynamic objects outside of any deflectors.
• Cloth - cloth objects are flexible objects which can change their shape.
• Rigid body - rigid body objects can't change their shape, only their position and orientation. Currently they are approximated using a simple spring model.
• Particle mass - this controls the mass of each particle in the object. This is taken in consideration only when two objects collide - the heavier object will push the lighter object aside.
• Smooth result - this option allows you to smooth the result. Smoothing is done with a simple Loop subdivision scheme.
• Iterations - this is the number of smoothing iterations that will be applied to the object.

Choreography properties
The properties in this rollup are global for all SimCloth modifiers. Changing these in one modifier changes them for all other modifiers as well.

• Simulation extent - controls the start and end frame of the simulation.
• Active time segment - uses the active time segment.
• Start frame - the starting simulation frame. This is ignored if Active time segment is on.
• End frame - the end simulation frame. This is ignored if Active time segment is on.
• Substeps - SimCloth divides a single frame in a number of intervals and computes the cloth position for each of these substeps. More substeps mean a more precise result.
• Gravity - the strength of the gravitational force acting on the objects. Gravity values come from the scene settings. Which by default is the Y-axis.
• Collision tolerance - the minimal distance that SimCloth will try to enforce between colliding objects. Smaller values mean that object will be kept closer to each other, but increase the chance of intersections.
• Check for intersections - when this is turned on, SimCloth will check if any objects are interpenetrating at the end of each frame. If an intersection is found, SimCloth will double the number of frame substeps and will try to simulate the frame again.
• Adaptive subdivs - this controls the maximum number of times the substeps can be doubled if an intersection is found.
• Solver precision - controls the target precision for the non-linear conjugate gradient solver. Lower values mean a more precise, but slower, simulation. Values lower than 1.0 are preferable.

Forces properties
These properties control the behavior of the cloth objects. Note that all these values depend on the scale of your scene!

• Stretch forces - these properties control the behavior of the cloth with regards to stretching.
• Springs - selecting this option will cause SimCloth to create a simple spring force. Each elementary spring force acts on the two vertices at the ends of an edge.
• Stiffness - the resistance of each spring to stretching.
• Damping - the resistance of each spring to velocity difference of the two ends of the spring. Lower values will make cloth more "springy" and oscillating. Higher values will reduce oscillation.
• Stretch/Shear - this force model is slower than the springs; however it tries to model more accurately the internal structure of woven clothes. It considers the cloth as made of perpendicular strings. Each elementary force acts on three vertices of a triangle.
• Stretch - the resistance of the cloth to stretching in the "string" direction.
• Shear - the resistance of the cloth to shearing (changing the angle between the two string directions).
• Damping - resistance of the cloth to changes in velocity between the vertices of a triangle. Lower values will make cloth more "springy" and oscillating. Higher values will reduce oscillation.
• Bend forces - these properties control the behavior of the cloth with regards to bending. An elementary bend force is based on closed (internal) object edges.
• Enable bend forces - this turns bend forces on and off. Using bend forces produces a more realistic cloth.
• Springs - this option will use simple springs for bend forces. While this option is fast, it does not model bending forces in a very realistic way.
• Stiffness - the resistance of the cloth to bending.
• Damping - the resistance of the cloth to changes in the bend configuration.
• Face angle - this option will use a more realistic bend model, based on the angle between neighboring faces.
• Stiffness - the resistance of the cloth to bending.
• Damping - the resistance of the cloth to changes in the bend configuration.
• Air drag - controls the effect of air on the cloth.
• Amount - the effect of surrounding air. Lower values mean less effect. Higher values make the cloth appear denser and moving slower through the air.

Collision properties

• Self-collisions - this has effect only on cloth objects; enables/disables collisions between parts of the same object.
• Friction - this controls the roughness of the cloth. Lower values will cause the cloth to slide over other objects.

SimCloth Modifier on groups

This can be used to assign different properties to groups within an object.
To add a new Polygon Modifier to a group, turn on ‘show more than drivers’ next to the object’s shortcut in the choreography (in the Project Workspace), from the popup menu, choose Add Polygon modifier->SimCloth.

• Add Group- right-click on the newly created Polygon Modifier and choose ‘add group’ allows a group to be chosen from the Custom Group list box.
• Group list - the list box contains all the groups.
• Attached - this allows you to attach the control points of a group to another object or group. Turning this ON will mean the control points in the group or object will NOT be affected by the simulation, but will move based on the motion of the object.
• Collisions - enables/disables collisions for the vertices in the group.
• Self-collisions - enables/disables collisions for the vertices in the group.
• Check for intersections - enables/disables intersection checks for vertices in the group.
• Scale - this controls the cloth scale for the vertices of the group relative to the original cloth position. You can animate this to "shrink" the cloth around a given object.

SimCloth is created by Vladimir Koylazov (Vlado). Original source code was released as ‘Open Source’ (see opensourcelicense.txt) SimCloth was ported to Animation:Master by Bob Croucher at Hash, Inc.


Adding a single SimCloth Modifier to an Object:

Open TorusTutorial.prj

Your Project Workspace and properties panels should be visible
-Right-click the sphere in the choreography window and choose Add Polygon modifier/SimCloth from the popup menu.
In the SimCloth properties change the Object Type to ‘Deflector’. Leave all other properties at their default values.
-Right-click the cloth in the choreography window and choose Add Polygon modifier/SimCloth from the popup menu.
In the SimCloth properties change ‘Subdivisions’ to 16, ‘Smooth Result’ to ON and in the ‘Forces’ property, change the stretch type to ‘springs’ Leave all other properties at their default values.
- Right-click the torus in the choreography window and choose Add Polygon modifier/SimCloth from the popup menu.
In the SimCloth properties change the Object Type to ‘Deflector’. Leave all other properties at their default values.
Now, right-click in the choreography window, and choose Plug-ins/SimCloth Simulate.

Adding multiple SimCloth Modifiers to an Object using groups:

Open FlagTutorial.prj

Your Project Workspace and properties panels should be visible.
-In the Project Workspace, find the shortcut to Flag in the choreography. Turn on ‘show more than drivers’ so you can access the Flags groups in the choreography. Expand the groups folder so you can see the groups.
-Right-click the cloth group and choose Add Polygon modifier/SimCloth from the popup menu.
In the SimCloth properties change ‘Smooth Result’ to ON. Leave all other properties at their default values. Right-click on the SimCloth modifier you just added and choose ‘Add Group’ from the popup menu. A new property will appear called ‘Custom Groups’. Expand this and set ‘attached’ as the Custom Group.
- Right-click the pole group and choose Add Polygon modifier/SimCloth from the popup menu.
In the SimCloth properties change the Object Type to ‘Deflector’. Leave all other properties at their default values.
-In the Objects folder, find the Flag model, expand it so you can see the groups, find the ‘attached’ group in properties, set Plug-in Properties/SimCloth/Attached to ON.
Now, right-click in the choreography window, and choose Plug-ins/SimCloth Simulate.


Feel free to experiment by changing settings and re-simulating!

**(correct projects should be flagtutorial.prj and torustutorial.prj)
** corrected gravity property description

Here is another project: DianeDress.prj