Hi, long time no see


how would i go about being able to walk on a round surface. i want to accomplish something like that 3D bonus round in sonic and knuckles where you ran around a sphere and collect those balls hehe. i want to be able to walk around a sphere without falling off.

i hope you understand what i mean. i want to make my game worls on spheres instead of flat ground. any help or turorials would be grately appreciated

thanks guys xx

Well, try to use a normal ent_move/ c_move movement code. Use a absolute vector for gravity. This gravity must be turned with a sin/cos instruction. It must be changed by every movement the actor does. The actor must have a pre-calculated position, where sin and cos calculations begin. Hm, it is like a third person camera, which turns around a player. If you move along a spere-model, you have to youse c_move, i think.

I havn't tested this idea. It's, well, an idea.

I try it out. If nobody understand it, im sory

it is a good idea with this spheres. Like in the game prey. I will post my solution if i succede (is this the right english word ?)

MfG,
Ich

He is right. Just create a vector from your position to the origin to simulate gravity. When you simply want to move around a perfect sphere, you just can use fixed vector math without caring of collision detection, etc.

One problem which you can encounter is the so called gimbal lock (see http://www.anticz.com/eularqua.htm). It will happen when you pass the equator from the north to the south pole. You can solve this with quaternions (http://www.gamedev.net/reference/articles/article1095.asp) when you are moving in 3D Space.

"As rotations in the Euler representation are done with respect to the global axis, a rotation in one axis could 'override' a rotation in another, making you lose a degree of freedom. This is gimbal lock. Say, if the rotation in the Y axis rotates a vector (parallel to the x axis) so that the vector is parallel to the z axis. Then, any rotations in the z axis would have no effect on the vector."

That sonic thing was a pure (but good) software emulation, so it was just a repetitive pattern they used.