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Member Since 30 Aug 2012
Offline Last Active Oct 18 2013 01:09 PM

Topics I've Started

Starting out with tile graphics

03 November 2012 - 05:45 PM

I've recently been playing with the idea of making an RPG for a legacy system, specifically the Game Boy Advance, and I'm trying to learn how to draw up a decent tileset. I've found some good tutorials on the subject, so I grasp the basic concepts of pixel art, but I'm trying to refine my techniques. So far, I've got tiles for a couple of surfaces (rocky cliffs and grass):
Attached File  tiles.png   1.33KB   41 downloads
This is how they look when tiled:
Attached File  test.png   3.57KB   39 downloads
I'm mostly happy with the rocks, even though the grid is pretty obvious, but the grass is only mediocre.
If anyone has suggestions on ways to improve the tiles, I'd be quite happy to hear them.

If I end up actually doing this on the GBA, I'll need to limit myself to a 256-color palette and 16-bit color depth. Each tile will be 8x8, but I'm doing the initial drawing in 16x16 because that's closer to the size I'll make the characters.

Figuring out ellipsoid-ellipsoid collision detection

30 August 2012 - 10:50 PM

I've been working on collision detection code for a project, and I'm trying to figure out the method to use to detect collisions between objects. Since I use ellipsoids to test against level geometry, I'd like to use them for collisions between objects as well. The problem is figuring out exactly how. One method I've seen converts the ellipsoids to a sphere and an axis-aligned ellipsoid, which looks like a great solution, but the method involves finding eigenvectors and other advanced stuff that I don't really understand (yet) and would rather not have to implement.

It should be easy to convert the ellipsoids to a sphere and a skewed ellipsoid by applying a series of affine transformations.
I've read that a skewed ellipse is still elliptical, so the skewing is equivalent to a rotation and a scaling, and I assume that the same principle applies to ellipsoids. However, I'm not sure how to determine the rotation and axis lengths of the new ellipse. If I knew that, it would be easy to make the ellipsoid axis-aligned. After that, I'm hoping to be able to perform a sweep test, but I'm not sure how efficiently it can be done, and I haven't figured out the equations to use yet, although I could possibly figure those out with a little work.

I'm also considering working with other collision shapes if ellipsoids don't work out, but it would be really nice to be able to use the same shapes for object-world and object-object collisions.