Archive: 3 posts

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1. How do we calculate the numerical value of object's acceleration from the percentages in the tweak menus? Is object's mass and the force applied to the object related to this percentage? 2. In the tweak menus, unlike the acceleration and deceleration, "speed" has a numerical value. When reached that speed, does the object move with zero acceleration or continue accelerating with the numerical value of the percentage? 3.How does dampening affect the forces applied to the object and acceleration? What exactly is it? Force or acceleration? If it is like them, how do we calculate the numerical value from the percentage? Thanks for helping! Apologizes for my engrish.

2011-09-03 20:30:00 Author: Yoove Posts: 1

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I can't give you definitive answers because I don't know, but I can give you what I think happens from my observations. 1) The acceleration percentages range from no acceleration (0%, the object won't move) up to full acceleration (100%, the object is instantly moving at the maximum speed). I guess what you could do to find the acceleration is time how long it takes an object to reach maximum speed. For now, this could be done by having one object move at some speed and see how long it takes another identical object to travel at that same speed. Or, when the move pack comes out there's a sensor that can determine an object's speed. In addition, from the Wiki: "The weight of an object in LBP is measured in sackboys. You can find out the weight of a shape by placing an In/Out Mover on it, closing your Popit completely, making sure you're not in Pause Mode, and then opening the In/Out Mover's tweak menu. The weight will be shown under Current Weight." This is useful because an object's mass does indeed affect acceleration, metal being larger than cardboard for example. The exact parameters of each material can be found in the Wiki too, though the mover technique will be more useful. The mass also affects the force an object has - metal will hit things harder and need a larger opposing force to stop it than an equivilent shape of cardboard would. 2) Once the object has reached the maximum speed it will stop accelerating, the acceleration percentage solely determines the amount of time it takes to reach said speed. 3) Again, like acceleration, dampening ranges from no effect at all (0%) up to full dampening acting like dark matter (100%). I'd presume that dampening simply increases an object's inertia, a value that varies between materials. I don't really know how you'd go about measuring it exactly but the dampening force has a much larger effect than the acceleration force, given that the former can completely void the latter. Now get ready for someone to come in who's actually analysed this properly and show everything I've said is complete balony.

2011-09-03 21:38:00 Author: Xaif Posts: 365

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A few clarifications/corrections... The acceleration percentages range from no acceleration (0%, the object won't move) up to full acceleration (100%, the object is instantly moving at the maximum speed). 100% is not quite instant, e.g. for a basic Mover, it takes one simulation frame (1/30th of a second) to accelerate to the Max Speed setting once the Mover is enabled. Ditto for a Follower, which is why an object with a Follower always lags one frame behind whatever it's following. As for the intermediate values, I don't believe they represent a linear scale, i.e. if 100% is, say, 10 ms-2 (metres per second per second), I don't think 50% is 5 ms-2, but I've never actually measured it. This is useful because an object's mass does indeed affect acceleration, metal being larger than cardboard for example. The object's mass doesn't affect the acceleration applied by a Mover, but rather the force applied to the object, using the traditional Newtontian mechanics formula F=ma (force = mass x acceleration). So a block of cardboard and a block of metal will accelerate at identical rates given identical Mover settings (ignoring all other forces acting on them). Glued objects count as a single object from a mass calculation POV, but there's a slight oddity when dealing with two objects connected with connectors (e.g. bolts). If a Mover is attached to just one of the objects, the game calculates the force required to satisfy the acceleration for that one object, but then applies the force to both objects, reducing the effective acceleration. So if you want two bolted objects to accelerate at 100%, you have to attach a Mover to both objects. Once the object has reached the maximum speed it will stop accelerating, the acceleration percentage solely determines the amount of time it takes to reach said speed. IIRC, with a basic Mover, this max speed applies to the directional vector of the the Mover, so if the object is travelling at Max Speed (or more) in a perpendicular vector, it can still accelerate in the direction of the Mover's acceleration vector. It's also worth noting that the object can exceed Max Speed due to other forces, such as gravity. I'd presume that dampening simply increases an object's inertia, a value that varies between materials. Dampening is a bit of a weird one - it's similar to friction, but is applied on a vector basis, which is unlike anything you'd encounter in the real world. AIUI, on an Advanced Mover, it's the deceleration value (in a traditional Newtonian sense) which is applied when the effective speed being applied by the Mover is less than the current speed of the object. So if you use an Advanced Mover to change an objects direction from going up to going right, the acceleration value is applied to the vector along the x-axis, while simultaneously applying the dampening value to the vector along the y-axis.

2011-09-04 19:13:00 Author: Aya042 Posts: 2870

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