Starting with Blender 2.41 you can bake game engine hard body dynamics into animation Ipo curves.
Setting up world physics
First set up the world physics. Go to Shading context (Template:K) , then the World sub-context , and control that the physics engine is set to Bullet :
Setting up your scene
Now set up your scene. In our case we will place a line of dominoes on a plane.
Create a plane (Add → Mesh → Plane) and some dominoes (Add → Mesh → Cube), arranged as shown.
Setting up collision objects
Next select one of the objects that will collide - in our case the first of the dominoes in the line. Tilt it toward the second (rotate) - we’ll start it tipping over and let Blender do the rest.
Now for each of the objects (in this case, the dominoes) that will collide:
- Go to the Logic context (Template:K) and click on Actor.
- Select RigidBody in the drop down list.
- Click Bounds.
- Change the Collision Bounds type to Convex Hull (other types can be done but are more complex to setup).
Do this for each object that will be involved in the collisions. The plane (ground) in this case should not have its logic Actor and Bounds set. Although it does interact with the other objects (in this case, supporting the dominoes), if we set it as a dynamic it too would fall away by gravity. So, it will be a static actor.
Also do not forget that physics objects have to have a material, or they will bounce around wildly because they need the damping values etc. which are not set on objects without materials.
Press Template:K to see a preview of the game animation.
Press Template:K when done.
Get ready to bake
Go to the Scene context (Template:K).
Select the Keyframe start and end range you want the animation you record to start and end on.
Record the Ipo
Select Game → Record Game Physics to IPO.
Press the Template:K.
Press Template:K when done
Scrub through the animation
Now you can scrub forward and backwards through your animation with the arrow keys, and look at the animation curves in Ipo Curve Editor by selecting an object.
Replace the animation
If you change something and press the Template:K the old animation will be recorded over if you have Record Game Physics to IPO still enabled.
Troubleshooting and hints
As with all physics systems there are a number of limitations that you need to be aware of - please see this page for tips, tricks, and limitations.