By Reto.Hal9k, Render Programmer
We already had a vegetation system similar to what exists in other games, but performance got really bad as soon as we moved the clip plane further away from the camera, so I started to look into other solutions. I had some ideas that I needed an algorithm that would work somewhat like our terrain drawing, where the terrain would get coarser in the distance.
Terrain rendering getting coarser with the distance
So I started with a regular pattern that essentially would keep the overall structure across LOD boundaries, in order to keep popping artifacts at a minimum.
Terrain vegetation using a regular distribution
I tried various solutions to try and hide the obvious tiling, but none I could think of were good enough. I then looked into a different solution inspired by the paper by Kevin Boulanger Kevinboulanger.net, as can be seen on the screenshot below:
Grass rendering using the proposed method of Kevin Boulanger using his texture
And it worked really well for low vegetation like grass. But I wanted something where there was more variance in the visuals. So I went back to the idea of using a system like the terrain rendering but now I experimented with an irregular structure for the vegetation.
Irregular mesh structure for vegetation
And I felt it looked more chaotic which was what I needed to get enough variance. Based upon this method I expanded the method to allow for up 4 different kinds of vegetation packed into a single draw call. Below is a debug version that shows where the different types of vegetation would be drawn.
Different kinds of debug vegetation
And here is a screenshot showing the same scene with vegetation:
Terrain vegetation without anything else
And now the same terrain with everything else:
Terrain vegetation with the rest
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Looks great, I definitely think that the problem of vegetation disappearing in the distance is extremely annoying. I remember this being a big problem with BF2. Keep up the awesome work guys!
And not only BF. Even now AAA games have that popping up gras and vegetation in the distance. Footage I've seen from Skyrim for example indicate this quite a lot (I know this is not a competitive game but it looks really odd when you walk across a field and the grass just pops-in in a radius around you)
Awesome stuff.
That only happens on certain settings.
Ground breaking stuff. Good job.
This is great. LOD popping is one of the most unimmersive and annoying things in game. I think it was Crysis 2 on the xbox where the defence bollards would keep popping in and out of view in the distance, but you could still see the characters standing behind them.