Archive: 6 posts

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Before I start, sorry if this is already here - I did look but I couldn't find anything. I want to make an object move straight up, using rockets. However, whenever I try this the object tend to veer off to the side. Any ideas how I can get it to keep going upwards? Thanks

2009-01-25 11:07:00 Author: Coxy224 Posts: 2645

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I've not used rockets like this yet, so these are just educated guesses. My guess would be that either your object has uneven weight distribution or your rockets aren't placed correctly. I'd try experimenting with a basic prototype first and gradually make a more complicated object. Maybe something simple like a square with two rockets at the base. The other option is to cheat and have the rocket 'on rails', in the background have long, hollow rectangle of dark matter (going all the way up to your destination), have a glass square inside the dark matter rectangle and glue the glass to your rocket. Several people here have made rockets and can probably give better solutions than me. But at least you have a place to start.

2009-01-25 11:55:00 Author: EastwoodAndy Posts: 70

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Rockets are very sensitive beasts with very fickle settings. Let me first talk about acceleration... You can't slide the boost amount between the different notches you have, all the settings are pre-built. So if you move it up or down one boost level, most likely your flight path will be completely different. Another thing to be aware of with rockets is that they provide constant acceleration if turned on normally. That means the longer they fire, the faster they go. If they hit things or go up this slows the process down though, but the movement of a rocket is different to say, a motor bolt, which when normally used provides a steady velocity as opposed to a steady acceleration. Velocity is how fast something goes at any given time. 60km/ph is an example of velocity. In one hour, an object will move 60km. Acceleration is how fast a thing will increase it's speed. So something with, say, an acceleration of 10km/ph will every hour go 10km faster. First hour 10km/ph, second hour it's velocity is 20kmph, third hour 30km/ph. It's a speeding up over time. --- Now let's move onto balancing... In terms of balancing, having a non-centered weight will make it veer, that being the same amount of weight on the left and right side of the rocket vehicle. Having the rocket off center from the middle of the rest of the vehicle will also make it veer as well. Rocket placement in grid mode is fiddly, it's very hard to get it dead on. Finally, having the rocket at an angle from the base will make it veer as well. If you have built by hand rather than grid mode it might not be dead straight, no matter how straight it looks. It's not entirely impossible to make a rocket fly dead straight up and down, but it's a difficult thing to do, especially if the rocket itself is heavy or the boost levels are high. Another thing to consider is that sackboy has an actual weight in the game. If they are in/on the rocket itself and moving about, that will also make the rocket veer off from dead center. I've used that concept to guide my TSR - Three Stage Rocket, but this could be one more factor to consider. It's near impossible to get the player to stand dead in the middle. Even if you have a small grab switch, the sackboy can still move about to a limited extend will grabbing. They can also let go at any point and move about. Finally, if there is more than one player, the others can move too. One more thing to be aware of is that if a rocket is just set to "on" and never turns off, well, it will keep pushing. If you fire a rocket straight up and it's prefectly balanced, well, it won't come down unless you turn it off. If it hit's the roof of the level and it's not a dead flat roof or nose of the rocket, well, it's going to come down at an angle. --- So lets find an easier solution... So... the much much simpler option that EastwoodAndy recommended, the on rails idea, is the easier way to acheive the up and down effect. There are several ways to go about this... One is to be obvious and have visible rails, most likely dark matter covered/stickered up. Another is to use a little known situation where if you have two thick layers glued together, you can place a thin layer of material between them and the two will still move together. Using this principle you could... Hide the rails from sight, just have an extra layer of rocket which stays between the rails or... Have the rocket on a piston set to stiff, and have a rocket set to boost 0. This gives no actual thrust but makes it look like it's firing. You could then get the piston behind the screen to move the rocket dead straight up and down. So... that's all you need to know about rockets going up and down. Thanks for your time. Hopefully it answers your question and you have a better understanding of how the rockets work in game.

2009-01-26 01:04:00 Author: Elbee23 Posts: 1280

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I have something to add from experience: a LBP Rocket differs from a real-world-one in this fundamental respect: it doesn't move relative to its surroundings, but relative to the whole scene. Effectively, 'surroundings' refers to the things it is attached to and the things it moves through. In other words: while a real-world-rocket moves the things it is attached to by pushing away the things that it moves through, a LBP-rocket moves the things it is attached to by pushing away... the whole world (think of a familiar trick in racegames where the car isn't really moving, but instead it is the whole scene that moves around the car). So, the point of reference relative to which the LBP rocket moves is a fixed point in your scene (like for instance the lefthand upper corner of a level). The way I discovered this is that you cannot actually make a 'blast chamber'. For instance: mount a rocket on some dark matter so it remains fixed, and put a loose sheet of cartboard right behind the exhaust pipe and set the rocket to full blast. In the real world the sheet would be blasted away. In LBP nothing happens. So the laws of action and reaction in LBP are a bit of simplified digital magic. The surroundings do determine the orientation of your rocket and its flightpath though: if you have a launch platform that holds your rocket, and you aim it upward or to the side, that will determine the direction your rocket will blast off to, obviously. It's just that the rocket doesn't 'push off' against the platform. Also, the weight-distribution of everything attached to the rocket remains very important for the flightpath. To you, all this has some advantages: you can make everything out of cartboard as rockets don't actualy 'touch' it anyway. Also, you can stamp rockets anywhere in the body of your rocket, not only the bottom. They don't need the free blastspace or the blastchamber to launch from anyway. If you want to balance your rocket, this means that (it's worth a shot) you could make a very heavy metal bottom and a cartboard body with ONE rocket in the nose to pull the whole thing up (obscured from view of course). You could also add some rockets with blastforce set to 0 to the base of your construction in order to simulate exhaust smoke. Hope this helps. *edit: It doesn't matter to the rocketproblem, but my explanation of action and reaction in the real world isn't entirely correct. A rocket ejects parts of itself (and thus of the craft it is attached to) to manipulate its momentum. That's why rockets can move through outer space where no air or other stuff surrounds it and from which the rocket could 'push off' - but again, concerning little big planet, everything I said still applies. Sorry for the scientific ****-up*

2009-01-26 14:48:00 Author: Wonko the Sane Posts: 109

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Thanks to everyone for the help here, I have really got a better view of how rockets work in LBP and how to use them. Thanks a lot!

2009-01-26 20:30:00 Author: Coxy224 Posts: 2645

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Hey, I just got an idea that might be something (if you didn't get there already). I made this sketch: http://www.lbpcentral.com/forums/picture.php?albumid=258&pictureid=2148 The black triangle is the body of the rocket. And this is what I would make of it: the bottom is heavy; the rest is cartboard; and the read circle with the bright green box is a cylindre with a rocket inside it. I would somhow bolt this cylindre (the dark green dot) to the nose of the rocket and hope that the fact that the cylindre can rotate, somehow corrects for any assymetry in the body. Think of it as sort of a plumb line like masons use. Also, make all shapes in grid and as geometrically symmetric as you possibly can.

2009-01-26 21:56:00 Author: Wonko the Sane Posts: 109

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