Blender 3D: Noob to Pro/Soft Body Animation

From Wikibooks, open books for an open world
Jump to: navigation, search

Due to rapid updates in Blender, some menu items may be different from those mentioned here. If the menus don't agree then just do what seems logical.

Softbody makes each individual vertex its own object that falls according to gravity and reacts to outside forces like fields. By adjusting the settings, you change the behaviour of the edges that connect the vertices. For example, you can make it so edges can stretch really far (aka elasticity), allowing the vertices to become distant, or you can make the edge stiff, so the vertices will always stay the same distance apart.

To put this in perspective, picture two cloths, one elastic and one cotton. The elastic one has edges that can extend, so if you view them in wire-frame (with vertices and edges visible) you would see the edges are more extended than an equal distance. The cotton one would only stretch a little bit, so the vertices would stay essentially the same distance apart.

We are going to make a big rubber ball, but not a big bouncy one, a flat (and somewhat lifeless) one. Start with a sphere. I would use a cube sphere or an icosphere, UV spheres don't deform well as they have too few vertices. A cube sphere is made by subdividing a cube and doing a "To Sphere" in the Edit window, under Mesh Tools.


Move the sphere up and place a plane below it. Make sure to do this in the right views so that it is aligned properly. Gravity acts on the z-axis (sphere should be above the plane relative to the z axis).

Tut.sb.1.jpg


Now for the soft body select the ball and go to the object tab then the physics subtab or whatever your version has. Click "enable softbody" and then turn up 'Grav' to 9.8. Click off use goal. Press the > arrow key (a few times) and you should see the ball fall. The center will remain in place but this is not a problem. If you are on a slow machine you will notice lag. This is because blender moves it vert by vert, not efficient.

Note: in Blender 2.49, you must deselect the "Use Goal" button to release the center of the ball. Otherwise, it will just hang there.

Note: In Blender 2.44, click F7 on keyboard, select the "Physics Buttons" button, select "Soft Body".

Tut.sb.2.jpg


When it reaches the plane it will pass through. To fix this we must make the plane affect the softbody. To do this make the plane deflect in its physics buttons.

(Noob Note: To do this in version 2.49 select the plane, go to object buttons -> physics context -> collision subcontext and select Collision. The variables you can play with here are under the Soft Body and Cloth Interaction.)--WithAlligators (talk) 10:00, 9 March 2010 (UTC)

Tut.sb.3.jpg


Now the ball collapses into a strange quivering wreck after impact. To fix this, you need to turn on the stiff quad button, but set the edge stiffness down a bit, so its more bouncy. You can use the bake function to solidify the settings see below

Note from Noob: You might have to turn up the Rigidity Level to 0.100 (in the Soft Body Tab) as well in order to prevent the object from collapsing. (I used a subdivided cube as Object)
What I recommend to do before rendering as animation: In the Bake Settings (Soft Body Tab) Set Interval to 2 or 1, so the object will not start deforming too early before impact. This will slow down the bake process - just slightly - but make the object bounce more dynamically. Then bake again.

Noob note: In blender 2.46 you have to adjust the value of Be in the soft body tab, I changed it to 0.4

Tut.sb.4.jpg


another thing you could do is animate the scene. Just put up animation video and set frames at about 50. Go to object mode, select sphere and press i key, and select LocRocScale. =)


Explanation of Settings[edit]

I invite you to correct and expand these definitions:

Softbody[edit]

  • Friction: creates a resistance to movement of the whole object, like being submerged in a viscous fluid
  • Grav: the rate of velocity change due to gravity. Results in a constant -z force.
  • Mass: (Force = mass × acceleration) affects everything by making the object heavier.
  • Speed: tweaks the simulation to run faster or slower.
  • ErrorLimit: raise it and the simulation will solve faster but strange things might happen. Save frequently, as blender might go nuts with this or any physic simulation (but less so after 2.4)
  • Goal: makes the object try to return to its original position, useful at times, in the tutorial you could turn gravity off and key the ball falling and use this to keep it a ball.
  • use Edges: uses the edges a means of resistance to movement for the object. Helps to keep it looking possible

Deflection[edit]