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Yeltsin

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Posts posted by Yeltsin

  3. Posted

    I'll re-post an OFP aerodynamics/ballistics study that I did for the CoC Unified Artillery. This is directly just a copy and paste from the chain of command developer forums:
    I've had a more or less systematic approach in identifying the necessary variables. I made a set of spherical objects in O2 with different masses and volumes. I also made a number of diffent unit types - all using the spherical objects.

    I then proceeded with practical experiments to see what is relevant for the system and what is not. I dropped two different objects in parallel  while measuring time and velocity.

    Conclusions that could be drawn:

    [*] velocity is independent of mass of object (realistic)

    [*] velocity is independent of volume of object (not realistic)

    [*] velocity is highly dependent on unit class

    Next step was to check the recorded data:

    va1.jpg

    The relation isn't linear since OFP does simulate air friction.

    I made a simple polynomial fit to the velocity function and through explicit differentiation I could define the acceleration.

    Btw, you can see from the graph that the gravitational acceleration in OFP is 11 m/s^2 as opposed to the real world 9.8 m/s^2 smile_o.gif

    The air friction is even more visible in this example that shows the quotient between the velocities of two objects one dropped with Vz(0) = -100 m/s and the other with Vz(0) = 0.

    v1v2q.jpg

    Through repeated measurements with different velocities the air friction constant can easily be extracted.

    There are some bad news though. There seems to exist an unrealistic relationship between air friction in different directions. You get different acceleration along the z-axis if you just drop the object or if you fire it of with a velocity alog the x or y axis. I still have to investigate that. My preliminary model looks like this:

    d2sdt.jpg

    It's possible however that k is cross-correlated and a function of Vx,Vy and Vz or even worse that it is k* s''(f(v^2)) where f could basically be anything and pretty hard to get a direct measurement.  rock.gif

    After concluding that airfriction was indeed modled in a nasty non-linear fashion in OFP, we had basically two options:

    1) Numerically solving the diferential equation.

    2) Train a neural net.

    As a diffeq solver would require long CPU time for each solution a neural net was the prefered the choice.

    The next step was to collect data. There are five relevant variables that are relevant:

    1) Velocity (muzzle velocity of the shell)

    2) Range (2D range between firing point and aim point)

    3) Angle (elevation of the barrel)

    4) Zdiff (difference in elevation between firing point and aimpoint)

    5) Trajectory (Two possibilities: high angle solution and low angle solution).

    To get smaller, more accurate neural nets we decided to put velocity as an intrinsic property for each neural net.

    Here are some graphs of collected data:

    data600a.jpg

    v0 = 600 m/s.  X-axis: angle, Y-axis: range¨

    traj1.jpg

    mv300.jpg

    v0 = 300 m/s.  X-axis: angle, Y-axis: zdiff, Z-axis: range

    The first graphs shows the data that was given to the neural net to train on. After a lot of work on the sampling routines we managed to get good data for the neural nets. The results were very good. With the neural net targeting system we have a system that hits the spot on any range and zdiff. The highest muzzle velocity we sampled was 800 m/s which gives a maximum range of over 32 km.

    This is how for instance the 500 m/s neural net looks like:

    net500.jpg

    After the release of the CoC Unified Artillery, I'll release the basic program used to test the nets as well as the data collection and neural net pack. It can serve as a simple foundation for anybody that wishes to play around with ballistics in OFP. smile_o.gif

    oooooooohhhhhhh ahhhhhhhhhhhhh, look at the pretty charts biggrin_o.gif

  17. Posted

    the hight change command like in that site that made WW2 Bunker packs, they gave a command line for init field and it changed the hight of objects.

    AND

    I once had a command line that changed ANY Object into ANY object in the GAME!!!

    Does anyone know It because I was wondering if I could turn it into a weapon

    EXAMPLE: Having say, a woodFence that is actuly an AK-47.

  18. Posted

    My wish list

    1. Chainsaw (For civilian resistance)

    2. HAVE THE TURRETS HAVE RECOIL AND BOUNCE LIKE HELL DEPENDING ON ITS POSITION.

    3. Shotguns that work like shotgun with the spread

    4. M249

    5. Bipods! that work

    6. When bullet casings hit the ground they make REALISTIC sounds.

    7. NAPALM!!!!!!!!!!!!!!!!!!!!!!!!

  19. Posted

    When i bought OFP i thought that wehn you would get in an M113 that the door would open and you would go in... But I didn't see it, so could you guys make that more realistic? example: When you board the M113 your character opens the door, goes in and takes a seat or goes to the controls. Also, can you guys make the vehicles be able to carry other vehicles?

    Example: a jeep can go up a cargo plane and the actions menu pops up and has the option, "enter cargo plane in cargo-hold" so the plane can carry it to destinations.

    Also can the blackhawks (If there are any) have fast ropes like in Black Hawk Down for fast insertions.

    One last thing, can the bodies have some "Rag dall" physics?

    Example: Having some men geting out of a truck and one gets shot as soo n as he gets out, so he falls a few feet to the ground.

    Anyways thanks for your time if anyone working on OFP2 reads this and I hope you find it useful.

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