How to set Down Direction for gravity

Am a total noob as far as the game engine goes
I was hoping to use the game engine physics to animate a collapsing bridge using the write to IPO feature .
I made all the bricks that I wanted to collapse, actors, made them dynamic and they do collapse ok ! :slight_smile:
However they dont fall down they fall to one side :spin:
Somehow they don’t know which was is down
How can I fix this?:mad:

Also while I’m about it is there anyway to stop them moving at all until about frame 200? - I could edit them in the IPO but there are a lot of bricks!
Also They move very fast - I have upped the mass to huge levels which slowed them down but is there a better way of slowing things down a bit?

The z direction is up/down, so you have to orient the bridge such that the blocks will fall down in the -z direction

As far as speed goes, blender’s gravity is by default 9.81 u/s^2 (replacing meters with blender’s units). Scale your scene correctly, and this should fix your speed problem.

Thanks for your reply
I cant understand what happened to set the Z direction pointing the wrong way in the first place? I dont think I rotated anything - I did seperate the individaul bricks form the bridge object to apply the game engine physics to them - that might have messed things up

When you create an object does the Z direction always point up by default or does it depend on what view you are looking at? would an object created in “Front” view have a different Z direction to an object created using “Top” view?

Is there any way to alter Z direction after you create an object or do I have to start over again?

The gravity is applied to the global z axis, the way an objects points shouldn’t affect the gravity.