Modeling Destructibles

mallen

Hi, I've been having a problem with modeling destructible objects. My main problem is having the seams not show, mainly when the models bend. Any advice or can someone direct me to a thread that has discussed this in the past?

What i'm trying to do is model a wooden plank that is pre-broken, have the pieces put together and not have the seam show.

thanks in advance.

I am using 3ds max btw.

PredatorGSR

Depends on the way the engine does breakables. The last game I worked on, we modeled the initial model, and modeled the breakable pieces separately, and then when the player broke the object, the engine swapped to the broken model and used effects and physics forces to hide the swap. So the seam wasn't an issue because there was no seam in the initial model and when it swapped the pieces were flying through the air, or there was a puff of dust at the break point.

schoenrock

if you are planning to use UDK, you can bring in your model, and then create the broken parts right in the engine. you can even create parts that are inside the model that would show up after its broken. like, for example, if you have a cement block that breaks, you can have metal rods that go through it show up.

mallen

thanks for the quick replies. PredatorGSR, about the model swapping, I guess thats assuming the model is destructed completely. But lets say the scenario goes as, a cannon ball breaking through a wooden hull. what Ive been trying to do is model the plank, breaking it apart. the pieces consist of the parts that do not break off and the part that does, which will dissappear. am I making sense?
We are not using UDK unfortunately, but what are the modeling approaches for the cement block? are they the same as I described above?
Now I have found a solution, but I want to experiment with other methods. What I have done right now is model a full plank in max, break it in half, switched the ends, model the broken face of the plank, brought the plank with broken ends into zbrush and detailed it. And now I have a modular broken plank that I can connect which is also seamless. However, I have run into hurdles here and there, mainly structure issues, not neccesarily problems with the planks itself. So here I am, trying to look for a possible alternative, that I hope would be more effiecient.

PredatorGSR

Yea, the swapping method works with that technique. The programmers made it so that we could set a static flag on pieces that we wanted to stay stationary. Objects with a static flag would also stay under the joints if they were animated. So in your ship example, the cannonball hits the ship, the main part of the ship swaps to a model that has a hole carved into it and is flagged as static so it continues moving along a path and does not fade. The 5 wood fragments also pop in and blow out with explosive force and fade from the scene after 5 seconds.

The one issue that we ran into was that if the player was thrown into the object with an extreme enough force, it would be penetrating into the object in the split second before the new one swapped into the place he was located. This caused some crazyness, but the programmers were able to minimize this with code tweaks.

This was using havok breakables along with custom code additions btw.

NoisyMonk

This is not an entirely useful post - but if you can get your hands on Bad Company 2, they do an extremely good job with destructables. The engine definitely was coded with it in mind (a main selling point for the game) but I'm not sure which method they use. Probably swapping. Unfortunately there is no 'modding' support to get your own assets in-game.