Speed must change only the speed from simulation, but when I change to a lower value, it seams the gravity change. What I mean is, the simulation don’t is the same if I change the speed, someone can help understand why this happen ?
Hi Tiago,
When you change the speed of the simulation in the rigid body world then you change the time that the simulation spans in frames.
When you reduce the speed you are not reducing the gravity, you are reducing the time interval of each frame.
If I have a block at 0 on the Z axis the speed at 2 then at 24 frames per second on frame 24 the block will fall to about -20 on the Z axis {s = 0.5 * g * t * t = 0.5 * 9.81 * 2 * 2} because 24 frames is 1 seconds * speed 2. The block has fallen for 2 seconds. Each frame is 2 / 24 seconds {speed / frames per second}
Now reduce the speed to 1 and on frame 24 the block will fall to about -5 on the Z axis, because 24 frames is 1 second * speed 1. Each frame is 1 / 24 seconds. To make the simulation the same you need to increase the length of the simulation. 2 seconds at 24 frames per second and speed 1 you need 48 frames to reach the same point in the simulation.
So the simulation will be the same, but it is the same over a different number of frames.
I hope this helps
Martin