Creating a Billowing Flag

Creating a Billowing Flag

Designing a Shirt

 

Autodesk 3ds Max Tutorials > Hair and Cloth Tutorials > Cloth > Creating a Billowing Flag > 

Creating a Flag

Create a cloth flag from a spline object:

1. Load quickstart.max from your \tutorials\cloth folder.

   This scene contains a rectangular spline object named Flag and a cylinder named FlagPole.

2. Select the rectangle shape named Flag and apply the Garment Maker modifier to it.

   

   Modifier stack with Garment Maker modifier applied to the Editable Spline object Flag

   

   The resulting Flag object is now a 3D mesh.

   This turns the 2D spline into a 3D mesh that you can use as cloth.

   The corners of the new mesh get "rounded" because the flag spline was not set up correctly.

3. Delete the Garment Maker modifier.

   The spline object reverts to its original status.

4. Access the Vertex sub-object level and then select all four vertices of the spline (press Ctrl+A).
5. On the Geometry rollout, click Break.

   

   Flag with vertices broken

   This causes the segments within the spline to become independent, as shown above. This preserves the corners when you apply Garment Maker. Whenever you have a spline that changes appearance after the application of Garment Maker, check the vertices and break the ones that cause this kind of issue.

6. Exit the sub-object level and then reapply the Garment Maker modifier.

   

   Flag with Garment Maker applied

Apply and set up the Cloth modifier:

1. With the Flag object still selected, apply the Cloth modifier to it.
2. On the Object rollout, click the Object Properties button.

   

   This opens the Object Properties dialog.

   

   First, you'll tell Cloth which objects should be part of the cloth simulation. Currently only Flag is present in the left-hand column of the Object Properties dialog; the FlagPole object should be part of the simulation as well.

3. On the Object Properties dialog click the Add Objects button, select FlagPole, and then click OK.

   This adds the FlagPole object to the simulation.

   Next you'll set which objects are to act as cloth and which objects the cloth will interact or collide with.

4. In the list on the left side of the Object Properties dialog, click Flag, and then click the Cloth radio button.

   This tells the simulation that Flag is to be a cloth object.

5. In the list on the left side of the Object Properties dialog, click FlagPole, and then click the Collision Object radio button.

   This tells the simulation that FlagPole is a collision object with which the cloth object can interact.

6. Click OK to close the Object Properties dialog.

Run the simulation:

Before you simulate, it's a good idea to check the cloth scale to make sure you get the results you might expect. To do this, you'll measure the flag as it relates to the cloth simulation. Cloth works in real-world units to create its simulation, so it's important to make it a habit to check the size of your objects.

1. Go to the Create panel and click the Helpers button.
2. Click Tape, and then in the Front viewport drag out a Tape helper to determine the width of the flag.

   You'll find that it is approximately 165 3ds Max units in width. Currently, Cloth is set (in the Simulations Parameters rollout) to 2.54 cm/unit, which equals 1 inch per unit (2.54 cm=1 inch). So at 165 inches wide, the flag is 13.75 feet wide, which is a big flag. That's not unrealistically large, but it is big, which is something to keep in mind because it affects the cloth behavior.

3. On the Cloth Object rollout, click Simulate. Let the simulation calculate for a few frames. After about 35 frames, press the ESC key to stop the simulation.

   The flag falls to the ground because it is not attached to the flagpole in any way. To attach the flag to the flagpole, you will need to access the Cloth Group sub-object level and create a group of vertices to attach to the flagpole.

4. Click Erase Simulation.

   If you don’t erase the simulation after pressing ESC, when you click Simulate again, the simulation simply resumes from the point where it was interrupted.

Attach the flag to the pole:

1. Go to the Group sub-object level of the Cloth modifier.

   The flag vertices become visible.

2. In the Front viewport, select the column of vertices on the Flag object nearest the flagpole, as shown below.

   

   Vertex selection for FlagPole binding

3. On the Group rollout click the Make Group button, and then name the group FlagPoleSelection. Click OK to close the dialog.

   Now that you've made and named a group, you need to assign it to the flagpole.

4. On the Group rollout click the SimNode button, and then pick FlagPole by either selecting it in the viewport or by pressing the H key and using the Select Objects dialog.

   Alternatively, you could attach the flag to the flagpole using the Surface constraint, but that method locks each vertex to the triangle on the chosen object whose center is closest to the vertex. In the case of the flagpole, some of the vertices would be pulled toward the cylinder cap triangles to which they are closest, which might create unexpected results.

5. Exit the Group sub-object level.

Run and refine the simulation:

1. On the Object rollout click Simulate.

   The flag drapes down and is held up by the flagpole, but it doesn't seem to drape very naturally. This is due to the size of the cloth. Remember that you determined that the flag is almost 14 feet wide, so you now need to edit the cloth properties for the flag so that it behaves more realistically.

2. Click the Object Properties button, and then in the left-hand column of the floating dialog click Flag.
3. Change the Shear value to 350.0.
4. Change the U Bend value to 50.0 (this also changes the V Bend value, which is locked to U Bend by default).

   Altering these parameters forces the cloth to be less flexible, cause more realistic folds in the cloth drapes.

5. Close the Object Properties dialog, and then click Erase Simulation to remove the existing simulation data.
6. Click Simulate again to see the flag drape.

Add a wind force:

To make the simulation more realistic, you'll use a Wind space warp to make the flag flap in the breeze.

1. Go to Create panel > Space Warps > Forces and then add a Wind space warp In the Left viewport.
2. Rotate the space warp to point in the same direction as the flag, as shown below.

   

   Wind space warp placement in the scene

3. With the Wind space warp selected, go to the Modify panel and change the Strength value to 10.0.

   Next you'll tell the Cloth simulation to take the wind into account by adding it as a force.

4. Select the Flag object and then on the Object rollout click the Cloth Forces button.

   This opens the Forces dialog.

5. In the Forces In Scene column, click Wind01 and then click the right-arrow button in the center to move it over to the Forces in Simulation column. Click OK to exit the dialog.

   

6. Erase the simulation again and then click Simulate and let the new simulation run to completion.

   

   Flag blowing after simulation is complete

   You can see how easy it is to create a simple cloth object with Cloth. Now that you've had a taste of how the system works, try using the major Cloth features in the Designing a Shirt tutorials to build a realistic shirt for a character model.