Moving in the right direction
I made a ton of progress in the last week. Along with the Visual Engine mentioned in my last post, I finished the Movement Engine. Considering those were my major goals this week, along with cleaning up the last bits of the engine (which I’m doing tonight/tomorrow), I’d say I’ve made great progress.
I made a major push in the last few days and completely recoded the movement engine. I implemented (then reimplemented, then optimized) a QuadTree and implemented the Separating Axis Theorem for arbitrary convex polygons (defined by a list of vertices). It was a beast to get all of the vectors pointing in the right directions at the right times. It was even worse trying to hunt down errors. I ended up recoding a lot just to fix some problems (and made things more efficient in the process).
For example, at one point everything was bouncing as if I were using simple axis-aligned bounding boxes. I wasn’t, so it was kind of confusing. After hunting around the collision detection code for a while (tons of breakpoints >.<) I still couldn’t find it. I took a bit of a break and came back to it later, where I found out that some of the optimizations I had performed ended up biting me.
When I check for collisions, I only check objects that have moved. I take that list of objects and query the Quadtree. I’ve slightly optimized the Quadtree query so it’ll only return objects where the object’s bounding box intersects (or is contained within) the query rectangle. To make a long story short, my collision detection was always returning true, but the Quadtree query was working fine – so it looked like bounding box collisions. To make a long story short, I fixed it and it works great! Off to entity management!