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# stepsize of ODE

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Could anyone please tell me what "stepsize" in dWorldStep of ODE actually means. Is it simply time step ? or something else... I made a demo using ODE and in the dWorldStep if i use the frameTime as stepsize, the simulation runs awefully slow, almost as if itz running in super slow mo :S. But the mass, the forces and the overall system configuration is such that it should not be running that slowly in real life. I used -9.81 as gravitational acceleration and etc. How do i make ODE simulation FPS independent and at the same time making movement speed realistic ?

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It''s the time interval (in time units) between successive calls to dWorldStep. In ODE, if 1 unit of length=1 metre and 1 unit of mass=1 kilogram, then 1 unit of time=1 second.

You''ll want it to be small - about 0.01 or smaller for decent accuracy.

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I thought that ODE stood for Ordinary Differential Equations, and was math terminology. Now it seems like it''s some physics engine that I have not heard of. What is it?!

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ODE=Open Dynamics Engine

oh, heh, thanks

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Then why on earh would my demo run differently ( with different speed) on different machines.. :S. Am calculating the frame time in seconds.. and everything is in standard units ( meter, kg, sec ). Plus, i got one more confusion.. if the ''stepsize'' of dWorldStep was really time then putting in a 0 should practically pause the simulation right ? BUT THAT doesn''t happen rather the system becomes toooootally unstable and BODY position becomes infintity... as if something was divided by 0 !!!

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browny:

if you want to pause the simulation dont call worldstep...I''m not sure why passing a 0.0 wouldn''t pause it, but it seems like if you really want to pause the simulatioin you shouldnt call worlkd step at all...this is more efficient anyways

neko

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