# Movement on a curved planet surface

I'm looking for a solution for moving a variety of objects over the uneven surface of my planet. The idea is that I will have a number of objects that follow the planetary landscape moving about in random directions.

The planet surface is made up of 6 sphere projected planes, all have been displacement mapped to create a "bumpy" surface. A grid based movement system would be ideal as it lends itself to a lot of pathfinding solutions. I am also using Unity, so leveraging the Physics engine is an option, but past experience hasn't yielded very good results.

I'm having trouble understanding the best approach for realistic movement, would it be a matter of calculating gravity and then translating the object along its forward, right etc. Or on the other hand would It be more a case of pre-calculating the path from A to B and applying that movement.

I've looked all over for some ideas on this subject but have found nothing. A few suggestions would be greatly appreciated.

Thanks.

• Can you be a little more specific? Where are you having trouble starting? (ex: How to represent the objects, the mathematics behind how to move the objects...) Feb 16, 2013 at 1:17
• You need to research four topics: vectors (determining vectors from coordinates, adding vectors), cross product (and surface normals), object space, and world space. The solution will be easy with that knowledge. Just remember that motion is applied to objects with respect to the surface normal whilst gravity is applied along the vector of two centers of gravity. Feb 16, 2013 at 2:28
• @SAHornickel I have limited knowledge in that area, enough to get by but it seems expanding this knowledge would be a huge benefit. Thanks for your suggestion. Feb 16, 2013 at 13:26