Graphics Reference
In-Depth Information
After you've selected Record Animation, a check mark will appear beside the option, and it will remain act-
ive until you deselect it. This means that every time you press P to enter game play mode, the game physics
Ipos will be overwritten, so be careful. If you want to run a simulation and record it to a different action than
a previous simulation, select the object, and in the Action Editor window click the X beside the drop-down
menu where the action you want to save is shown. This disconnects the action from the object, so that a new
game physics action object can be written without overwriting what you already have. Remember to give
the unused action a fake user by clicking the F to the right of the action's name, if you want to save the ac-
tion for later use! In a design change between versions 2.62 and 2.63, actions are no longer given fake users
by default, resulting in them being deleted from the blend file whenever the file is closed.
Frame Rate and Simulation Speed
If you try this with the first example of this chapter or with an example of your own, you will surely notice that
when you press Alt+A or render your animation to a movie, the resulting simulation is in slow motion. This
occurs because the game engine uses a default frame rate of 60 frames per second (fps). This is desirable for
real-time graphics for several reasons, but it is much faster than is necessary for animated movies, which are
usually either 24 fps or 30 fps. This means that when you record actions from the game engine, the resulting
actions will be normal speed when played back at 60 fps but will be slower than half speed when played back
at 24 fps. Furthermore, if you use hand-keyed actions in the animation in the form of Action actuators, as de-
scribed inthesecondexample inthischapter,you'llfindthat theresulting bakedphysicsactions donotsyncup
properly with the hand-keyed actions in the animation because of mismatched frame rates.
To correct this in the game engine, you need to reset the BGE frame rate to match the frame rate of the an-
imation you want to create, such as 24 fps. This is done in the FPS field in the World properties area, shown in
