Let There Be Lightmaps

Lightmaps are officially a nightmare to implement. They seem easy, but I have found otherwise. The last four days have been a battle, but I have made significant progress in implementing this feature in Synergy.

I began with the code outlined in this tutorial. A number of modifications needed to be made, including accounting for multiple light sources and using triangular surfaces instead of quads. I also factored lambertian calculation into the formula. Adhering to the tutorial strictly, plus the minor modifications I made to the formula, I ended up with this strange result:

Puzzle #1

The streaks were caused by a value overflow with my premature byte casting. Working in dwords and then casting to byte after the clamp got me to this (after adding a couple more lights):

Puzzle #2

So it's obvious to see here the mapping coordinates are wrong. After systematically trying every single combination of texture coordinates for each vertex I discovered the closest result was this:

I smell victory close at hand...

This implied the texture needed to be flipped on one axis, so I changed the order the data was input into the bitmap, and lo and behold I had this:

Victory is mine!

Although its close to a correct solution, it's easy to see there are a number of artefacts present in the lightmap, such as the lit borders and holes in corners. All of the problems become much more visible viewing the lightmap in isolation:

Oh god damnit

Higher resolution lightmaps such as 64x64 mitigate the problem, but cut deeply into the framerate. I'm still considering how I can overcome this problem, but I discovered a number of documents and papers on the subject of lightmaps, so I'll be taking a read of those and hopefully gain a bearing.

I needed to implement a basic light management system in order to support all of this process, and it has lead to some rather nice results for the lighting overall in the demo. The main improvement is the addition of attenuation constants for each lightsource which coincide with those used to calculate the lightmap, leading to nice consistent lighting:

Yes, the trees are still around

And now for something that isn't to do with Synergy engine! I was talking to Nick online and he suggested we have a go at doing some sketching together using opencanvas. I've had my head so deeply in coding territory the last few days that it was a little difficult jumping back into drawing mode, but after roughly 15-20 minutes I had this horrible looking sketch of a person that resembles a damn night elf:

Mr Cumbersome

It's ok in some respects, very mediocre in others. Working with the construction was extremely cumbersome, and has highlighted the fact that I need to engage in more studies and revision of facial construction and anatomy theory. Still it was a good process to work through, and having Nick on hand to point out issues as they manifested was a new and interesting experience. We've agreed to spot each other's work (presumably studies) from now on, which I'm looking forward to.