Firepower - Muzzle Velocity - Maya Scale

[YMangolds]

How is the muzzle velocity for a firepower calculated in relation to the firepower's scale? For example, I've got a robot that has a M240, Machine Gun, 7.62mm that has should have a muzzle velocity of 905 m/s (2,970 ft/s) with a rate of fire of 650–950 rounds/min (about 12 rounds/sec). Due to the problems in Maya (non-craft related) of using any units besides the default (cm), we have our internal units set to cm but we call 1 unit (cm) = 1 foot. When the firepower is created it comes in gigantic like the rest of cdt and has values of 100 for scale in all 3 axis'. A scale of 0.5 makes it about the right size for the vehicle, and after setting that and setting its muzzle velocity to 905, I did a test recording. After 24 frames (1 sec) the first bullet that was fired had a z position of -220. I duplicated the firepower and moved it to the side of the first one and made it's scale = 1 on all axis'. After recording, its first bullet was also at -220 on Z after 24 frames but had traveled twice as far as the one from the firepower who's scale is 0.5, so I checked the world position of the bullet and found out that the one from the 0.5 firepower had traveled about -110 concluding that the velocity is related to the scale of the firepower. I also noticed that the bullets got closer together the farther they traveled but I have resistance set to 0 (gravity is set to 9.8 but that shouldn't affect horizontal velocity?). So in theory to get a firepower who's scale is 0.5 to have the correct muzzle velocity i'd have to multiply it by 8 if I were using 1 maya unit = 1 meter, but since we're saying 1 unit = 1 foot it'd have to be multiplied by 27 (24,435). But then I tried to set that and found out you can't set the muzzle velocity value in CDT higher then 1000 .

[Carl Buhre]

I'm sure Henrik can answer this (since he made Craft Firepower) Yuris, but he's at home sick today. I'll make sure he writes a reply when he gets back.

[Henrik Hansson]

Hello Yuris!

The muzzle velocity of the bullets are dependent on the scale of the gun in Firepower. If you scale down the gun to half, the muzzle velocity will also decrease to half. There is however a bug in the Firepower that always divides the muzzle velocity by 4. This is something that we will fix as soon as possible. We will also change so that you can type in larger values into the spinners.

The reason that the bullets get closer together the farther they travel is because the bullets get a small random speed decrease when fired that shows when travelled for a while. There should actually be a spinner for setting this random value so you can disable it and that is on the todo list for the Firepower.

/Henrik

[YMangolds]

On Luigi's YouTube vid on the firepower he said that you're changing the collision mesh. Any hints on what will happen with it?
With the current version I've noticed some problems with it:

1) My shell ejection firepower's bullets jump like 20 feet straight up when they collide with the ground mesh, then "disappear" shortly after. I think they might be getting scaled to either a ridiculous size or get the scale of 0,0,0 because when attempting to select other objects in the scene the shell mesh gets selected instead, but when trying to frame on the shell geo with it selected the camera frames the extent of the rest of the scene but the shell geo is nowhere in sight.
2) I've noticed a drastic difference in the muzzle velocity if the collision mesh is parented under some geo vs untouched (parented under the firepower's mesh). When having the collision mesh parented under the ground the bullets go about 1/4 the distance (and then jump like 20 feet straight up upon collision). An interesting thing I found was that when I reparented the collision mesh back under the firepower mesh and resimulated, the bullets still went 1/4 the distance. I noticed the trans and rot had some funky values (guessing its pos and rot relative to the ground mesh's when it was first parented under it and recorded), so I set the pos and rot to 0,0,0 and 0,0,0 and keyed that at the first frame, then after hitting resimulate the bullets resumed their original velocity.

While you're doing whatever changes you have planned for it, could you please add in my feature request -> http://craftanimations.uservoice.com/pa ... collisions ?

[Henrik Hansson]

Thank you Yuris for your observations and input!

We are aware of some issues with the collisions in firepower and we will try to improve the tool as soon as possible.There is no deadline for it yet but the plan is to extend the Firepower to a full physics tool with improved collision detection so the bullets can bounce around on the surroundings alot better. We appreciate your input and will add your feature request when we update the tool.