Cinema 4D Tutorial – C4D Soft Body Dynamics – Tutorial Part One
This is part one of a two part tutorial that I created for 3D Artist magazine last year. It is a great mag for tutorials, ideas and inspiration, so I suggest you check it out if you’re not familiar.
You can download the required files to complete this tutorial from here.
Find part 2 of this tutorial here
C4D Soft Body Dynamics
There are several ways that you could simulate an object filling with air in Cinema 4D. One solution could be to model the deflated and inflated mesh as morph targets and then use the Pose Morph tag to blend between these two states. The drawback with this approach is you need to manipulate your mesh to create both morph targets, in other words, you essentially need to model two objects with the same point count.
In this tutorial, Tim will show a technique of inflating your objects using Soft Body Dynamics. This approach is much less work intensive than using morphs as you only need to model the object once before inflation, and dynamics will do the rest for you.
By using dynamics to ‘model’ your blown up object, you have the flexibility to alter the base mesh at anytime and rerun the simulation. This means you can create a low resolution object to test your theory and then go back later and add in extra detail such as wrinkles and creases.
As well as introducing the basic principles of working with Soft Body Dynamics in Cinema 4D, Tim will demonstrate how you can use vertex maps for an added layer of control over the dynamics simulation. By weighting the object vertices, you can control the influence of the simulation at a vertex level, in this example you will use this technique to ensure the seams of the object remain stiff and help to maintain the overall shape.
Dynamics can be fairly unpredictable, so Tim will show you how to cache your result for speedy and consistent playback in the editor and reassurance that your scene will render correctly over a network. Once the dynamics has been baked we will add in some camera animation and fine tune the motion using Cinema 4D’s F-Curve Manager.
Preparing the mesh for dynamics
First of all you need to locate and open the starting project file called 3DArtist_BlowUp_Start.c4d which is found on the magazine cover disk. It is probably a good idea to copy this to a convenient location on your hard drive before opening the scene file. Once open, select the 3D Logo Polys object and hold down Alt and add a HyperNURBs or Subdivision Surfaces object. The starting mesh is fairly low resolution which will help speed up the dynamics simulation, we then subdivide the geometry to create a smoother surface for rendering later. Next select the 3D Logo Polys object and from the Object Manager menu, choose Tags – Simulation Tags – Soft Body
Creating a collision object
Press play and the object will drop down due to gravity, stop and rewind, then add a floor object to the scene. With the floor selected, choose from the Tags Menu – Simulation Tags – Collider Body. This adds a Dynamics Body Tag to the floor object and automatically sets the Dynamic parameter (under the Dynamic Tab) to Off. The floor will not react to any forces such as gravity, but it will act as a collision object to any dynamic objects in the scene. On frame 0, move the logo up above the floor and press play again, the logo will drop down, then hit and land on the floor.
Configure the dynamics settings
Select the Dynamics Tag on the Floor, under the Collision Tab, change Bounce to 90%. Select the Dynamics Tag on the 3D Logo and under the Collision Tab, set Bounce to 120%. To stiffen the object, switch to the Soft Body Tab, under Shape Conservation, increase Stiffness to 100. Now the logo is too stiff and almost behaves as a rigid body. To create rigidity on only the seams of the object. Drop the vertex map tag from the logo into the Map field for Stiffness. Increase the Stiffness to 500, where vertices are weighted 100% they will be very stiff, on vertices which are weighted 0% the stiffness parameter will have no effect.
Inflating the soft body
To inflate the object, we can use the Pressure parameter which is found under the Soft Body tab of the Dynamics Tag. Rewind to frame 0 and then press play, once the object lands on the floor (around frame 30), stop playback. Set Pressure to 1 and add a keyframe by Control-Clicking on the small animation dot. Move forward one frame and set Pressure to 50, add another keyframe. Move forward a few more frames and set Pressure to 25 and add a keyframe. Now when you play the scene, the logo will hit the floor, then inflate and bounce up.
Bake the dynamics
Once you are happy with the simulation it makes sense to bake the result. This will allow you to scrub the timeline and playback will be much smoother. If you intend to render any dynamics simulation using a network rendering solution, then baking is essential. Select the Dynamics Tag on the logo, switch to the Cache Tab and click Bake Object. After a few moments you’ll see the icon on the tag change to show it is baked and playback will be much quicker now. You can also bake ALL dynamic objects in your scene under Project Settings – Dynamics – Cache.
Animate a camera
Add a null object to the scene with a camera as a child. Zero out the camera coordinates and then set Z position to -600. Rotate and move the parent null until the logo is framed nicely. Add keyframes for the null rotation and Y position so the camera follows the logo as it drops. Around frame 30 when the logo inflates, add a keyframe for camera Z position, then move to the end of the project and set the camera Z position to -700. Open the F-Curve manager and adjust the shape of the curve so the camera snaps back as the object inflates.
Using Dynamics as Morph Targets
If you want the control of morphing and the simulation from dynamics, you can combine the two. Create a duplicate of your object, one with the soft body dynamics setup and one with a Pose Morph Tag. Enable points under the basic tab of the Pose Morph Tag. Hide the dynamic object in the editor and then drop this object into the Poses field of Pose Morph to create an absolute morph target. When animating the morph sliders you can blend the shape and use the dynamics object as a morph target.
For step by step instructions, watch the video below.