How do I prevent my building from crashing down?

When I press P, my entire building comes crashing down on the surface,
which is what I want in the end.

However, I don’t want it to fall in the beginning, because I want a cube
to hit it and then make it fall!


Here’s the picture, as you can see when I press P, the building is already falling. I don’t want it to fall,
however when I throw a cube at it, then… then I want it to fall :frowning:

I think it’s because my bars aren’t stacked perfectly on top of each other, but I have no idea how to stack them up perfectly.

I just watched a good tutorial about using logic bricks to control the fracture object.

http://www.directcg.info/how-to-use-fracturetools-inside-blender.html

I am sure this same logic can be used in your situation.

What I did was to create a box, use a mirror modifier to get 2 of them on either side. Apply the mirror modifier and apply any scales you might have made in object mode. Add an empty (explained later). Add an array modifier with an offset of 1 in the Z axis with as many copies as you want and set the empty as an offset object. Rotate the empty around the Z axis 90 degrees, now every other level will be rotated 90 degrees. Apply the array. Go into edit mode hit P to separate the cubes and choose by loose parts. Now you have a stack of blocks on top of one another without a gap, ready for simulation.