Development Snapshot 17

Once again, most of the work was graphics related. It's refreshing to be making forward progress on tangible things, rather than back-end stuff nobody sees but me.

The animation system was the first thing I tackled. I was looking forward to making great strides on this item. It took more time than I expected so I had to put off the final parts (eg: BVH importer) until the next snapshot. In theory, the player character is animating properly, I just don't have any way of loading animation files yet.

Debugging Frame Timings

After that I spent a bit of time upgrading some of the debugging information the game spits out about frame timings etc. I was expecting to make a few small changes and call it day, but I went a bit crazy and replaced my old profiler with a much more flexible system that does most of the setup automatically. I celebrated this success by upgrading the frame time visualisation to add some colours to represent different parts of the frame. This should aid in optimisation down the track.

Top secret performance benchmark

The first thing I noticed with the improved frame timing information was that my text renderer is slow, taking up almost 30% of the entire General render pass when there is very little text on the screen. Fortunately, the text renderer is due for an overhaul a few snapshots from now to add support for scrollable content windows. The side effect should be improved performance, which is great.

Waypoint Tweaks

I also improved on the look of the waypoint path from last snapshot, adding a dark border. This doesn't sound like a big deal, but the way I originally wrote the waypoint path creation, this was pretty tricky.

Not too bad. But we can do better...

The border helps the waypoint stand out a bit better from the terrain, and tidies it up a bit in my opinion. I also did away with the triangular shaped notch at the start of each run, and I've had a few ideas for improving it further, but they will have to wait until next snapshot.

The most fun part was writing some geometry code to ensure the width of the border is constant even when approaching the sharp point of the arrow tip. The problem looked like it didn't have an easy solution until I hit upon the idea of using similar triangles, and had great fun optimising the equation until I ended up with something downright elegant (in my opinion):

v = normal1 + normal2
l = (2 * distance) / v.LengthSquared()
result = v * l

There wasn't much on the survival side this time around, but I did alter the poisoning debuff to lower maximum health instead of just eating away at your current health for a period of time.

I also fixed a handful of miscellaneous bugs, most of which have crept in during the last few months.

Next Snapshot

For the next snapshot I have a few fun things planned. First of all, the BVH importer, which should allow me to finally put the animation to bed. Also on the agenda is starting to work on the first biome that the game will support.

My original plan for the start of the game involved the player washing up on a beach after the cruise ship they were on was destroyed. With this in mind I created assets such as Palm Trees, Wooden Barrels, Life preservers etc and set up my test level as a literal sand box.

Now that I've developed the story more, the initial setup has changed drastically.  At the start of the game the player will  be dropped in a Temperate Forest, which couldn't be more different than the acres of sand and a few scattered palm trees I have now. So, in snapshot 18 I'm going to start the ball rolling on the biome generator. It will be somewhat of an experimental feature, but hopefully there will be something interesting to show.

I've also decided on the visual style of the game, which is quite exciting. I'll pretty much have to throw away most of my game assets and start again, but I have so few I'm not that worried.

Development Snapshot 16

The main issue I ran into this snapshot was inflexibility of old code. I ended up having to revisit alot of code that is over 3 years old. That code was unable to be extended without introducing a horrific mess, so I took the high road and invested some time refactoring those ugly parts. This cost me some time, but the end result was worth it.

The majority of work this time was in the graphics area. I overhauled the look of the UI somewhat, replacing the WindowsXP-like windows with something a little bit more modern (in my opinion). I also rewrote a large section of my render loop in an effort to reduce frequent state changes. Instead of just blasting out draw calls, switching shaders and such on the fly, I now enqueue render jobs that are sorted to minimise changes where possible.

Skinning System

This was the major piece of work this snapshot. The first task was creating a rigged model in Blender.  I took my existing quick and dirty model and threw together a simple bone structure (after I watched a few blender tutorials). This fell together quicker than I anticipated, which perfectly set me up for bitter disappointment when I failed at the next few hurdles....

Next was modifying my collada importer to support bones. My previous implementation was done strangely to say the least. Looking at the code again after several years, I drastically rewrote it to be more flexible, and added the bone/joint data parsing as well. I lost a bit of time debugging why all the transform matrices had no translation component before I finally realised that collada matrices are Column-Major and I was assuming Row-Major. Once I got that fixed, the matrices looked right.

Then I had to rewrite my model class to handle the fact that there will be joints pushing and pulling the vertices all over the place, instead of being static. My previous incarnation of my model class was a hastily slapped together mess that came out of an attempt to get the code working again after one of my aggressive refactoring efforts over the years. I treated it as such and gutted it, also making it work nicely with my new render job system.

I then added in the vertex blending code. To aid debugging other parts of the skinning chain, I decided to implement software tranformation of the vertices, rather than use the vertex shader at this stage. (It's much easier to inspect values if they are in the CPU vs the GPU). The only bit of excitement here was initially my bone indices were off by 1, leading to the following image:

That sweet looking cape is actually his mangled torso.

After fixing that I decided that visualising the bones and joints would make it much easier to debug the vertex blending. I got really messed up by this. No matter what I did, the bones wouldn't render right when moved. I got the joints rendering correctly in their bind pose, but anything else and it would stretch at a weird angle. It took me several days of hair pulling, but the problem turned out to be the order of some matrix multiplications.

I knew I needed to multiply the joint's bind-pose Transform Matrix (BPTM) by the desired transform (Y), (in this case, a simple rotation), but whatever order I used, eg:  Y x BPTM or BPTM x Y, the end result was not right. Then it suddenly occurred to me that the bind-pose transform matrix is actually composed of a rotation and translation, and there was a 3rd place I hadn't tried putting the Transform multiply... in between! So I decomposed BPTM into R x T and put Y in the middle : R x Y x T, and holy crap... Success!

At this point I realised the next step of creating an animation system was going to have to wait until the next snapshot, which was disappointing.  On the plus side, the model's vertices are being transformed as per the skinning equation, and is rendering correctly, which I'm pretty pleased with.

Waypoints

To close out the snapshot I also overhauled the look of the player's waypoints. I'm not completely happy with the look yet, but its a great improvement over the temp graphics that I've had in there for several years now. It also forced me break down the paths into runs of straights and turns, which will be required for smooth walking animations later on.

Original style waypoints

New style waypoints

Next Snapshot

For Snapshot 17, the animation system is high on the list. There's quite a few sub-tasks to tackle though, so I'm not sure if I'll get through them all. The toughest stuff should be behind me, but I'll see what happens.