Thursday Tinker

Meeting Day

With a six hour talking appointment starting at 8AM, there was not much time left in the day for coding, but I managed to look into a few small areas.  The issue of the FISH-EYE issue has now been fully explored and the problem was that the Reloaded engine was passing in a horizontal FOV, but using it in the perspective matrix calculation as a vertical FOV value, and the aspect was fixed at 1.777.  The new version sets the aspect ratio based on the resolution you are running under, and the FOV is now providing a vertical angle. By default now, the buildings and high walls don't skew out of all proportion when you look at the sky, and for those users who want the old style back, just ramp up the slider until you get what you want.

Now when you look up, the fish-eye effect is virtually gone and you get the kind of perspective you might expect from more traditional games that set a reasonable 85 degrees for horizontal FOV rather than the 170 degrees that I was using before.

Where Those Draw Calls Go

I also wanted to find out why an empty terrain scene took 73 (SEVENTY THREE) draw calls to perform, and so before Thursday was out I decided to make a shopping list of what GPU calls I was making. Here they are:

12 draw calls for the two overlapping skies (day and night, one side per call)
48 draw calls for the BlitzTerrain module segment renderings (one viewpoint)
3 terrain object calls (to populate the texture painter, editor water plane, etc)
1 water plane draw call which lies under the flat terrain
9 draw calls for the nine-stage post process for Bloom, Etc
1 vegmap draw call to paint the texture paint to the paint camera

As you can see, we have a few questions to ask of our engine here. We don't need 12 calls for the sky, and when not transitioning, one sky mesh would do. So that's 11 calls that can be saved. The editor water plane is not needed in game, so should be removed, as well as the texture painter when in-game! A simpler post process shader could manage Bloom in fewer that nine passes I am sure. All told, I could probably shave off 18 draw calls from the above 'empty' scene. I also want to investigate the 48 draw calls to produce the terrain, just to make sure they are not being rendered twice, and at least to confirm I need 48 segment meshes. Maybe I can find some settings to fiddle with in this regard too.

Signing Off

Quite tired after today's various antics, so I will be starting my research into True Imposter technology on Friday, which I hope the fill in the last of the visual gaps in my performance boosting trinity and get those distant distant QUAD polygons textured properly. I had thought of fake QUAD textures, but it would take me as long, and probably longer to create a system to produce the fixed baked textures to accompany each entity you bring in.  I have a plan, and it should not take too long, so it's worth spending a day on.

It was also aired that perhaps progress is not as fast as the community may wish, and perhaps too much time is being given over to pure performance work. I think however that in the long term this 'boring' performance work will repeat rewards much later on when we take high frame rates and clever scene handling for granted.