Bound-boxes, centre of mass, chains and ropes

Game Engine, Players & Web Plug-in, Virtual Reality, support for other engines

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Posts: 10
Joined: Wed Oct 23, 2002 11:00 pm

Bound-boxes, centre of mass, chains and ropes

Post by Rotwang » Wed Oct 23, 2002 11:20 pm

Hi everyone, I have a few questions about the game engine for my first post.

First, is there any way to change the shape of an object's boundary box in the realtime engine? I've spend days experimenting with the actor options in the gamebuttons window, and haven't managed it yet, though it became eliptical for some reason in some configurations. Is there any connection between this and the bound-box shapes selectable in the editbuttons window? That has a list of things like box, cone, sphere, polyheron, etc, but the box that the realtime engine uses still seems to be spherical. This is annoying when you want to make a flat bottomed crate or something, that should sit solidly on the ground, but instead just rolls away. Also, there seems to be no way to define the centre of mass of an object except in the boundbox's centre.

Is there any way to do this, and if there isn't, does anyone feel the necessary modifications should be made to a future release? I certainly do, but I lack the programming skill to create a plugin or do anything like that.

Can one perhaps "cheat" and make up objects of multiple components with several spehrical boundboxes, perhaps, to approximate the overall shape of the desired boundbox?

Second question: Is there any way to set up inverse kinematics in an armature chain in the realtime engine, so you can produce stuff like dynamic chains, ropes, etc? All my experiments with armatures so far suggest no.

Finally, which of the regular motion controllers can be used in realtime? I've tried object parenting and constraints, and these seem to simply disappear and have no effect when the realtime engine is run. Parented or constrained objects just fall apart and do their own thing.

All these things are very confining for me, because I would really like to use all of the above features in my game project (haven't done much work in Gameblender yet, but I'm exploring as many possibilities for development as possible).

Any suggestions?

Posts: 166
Joined: Wed Oct 16, 2002 6:52 am

Post by Saluk » Thu Oct 24, 2002 4:55 am

No center of mass

Nothing except sphere's

Using python scripting you can fake more rectangular collision detection

Your box shouldn't be "rolling away" as you mentioned. Check to make sure RIGID BODY is not selected. Rigid body is only for balls.

Parenting works, but if you have a DYNAMIC actor as a child, it wont follow the parent. Dynamic actors can only be parents, not children.

No dynamic chains/ik etc. You can only have armatures with premade actions. With some scripting, this could be done as well, but not too many peopel have made good use of scripting the heck out of the game engine:) A math wiz could probably pull something like this off.

In the future, the physics engine will be completely replaced by another one, and will most likely have many of the features you wish built right into the physics engine. As of now, you pretty much have to rely on scripting tricks.

Stay tuned for updates:)

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