my final thoughts , I wonder if NV3 will comment on this thread, it was 2020 when I last posed this question .
zec replied
Hi All
Unfortunately trees are a major issue for most games developers, and a LOT of money goes into this area in most cases. This is why companies such as IDV/SpeedTree have become so extensively used, as their tools allow for extremely good tree generation relatively easily (compared to trying to hand make the same tree in a 3D modelling tool, or trying to make billboards look like 3D trees).
Unfortunately, in modern gaming environments, flat planes for trees are exceedingly hard to handle without making them stick out like a sore thumb. This is why they do change when changes are made to the rendering methods/systems in Trainz. The more realistic you make the game engine, the more they look like flat/flattish planes.
In particular, if any shadowing is applied to a billboard tree, it suddenly looks poor due to the flat-plane nature being highlighted by the shadows. Shadows can be disabled on specific meshes, but it isn't currently possible to prevent a shadow being cast onto a mesh (and doing so may not work visually as you would now have shadows behind that mesh but not on it!).
The same applies to shading (ie if the surface is lit or unlit), as your light vs dark has a hard line.
Twisted billboards, as in Clam1952's trees, can make big steps toward mitigating some of this, but they are still effectively flat in nature. Unfortunately this means that the shading still shows up the flatness.
There are some possible options to work around this, but these can introduce major problems as well. Either for the creator, or for the visuals, or for everyone...
One is to remove all directional lighting from these objects; which is how billboards were handled in earlier releases. This however introduces a lot of issues with matching them with the surrounding environment, as surrounding objects (including other trees) may be lit by the sun and yet the billboard tree is only being lit by ambient light. There are also issues with other areas with this, including limited or no normals map ability, and a potential to break the PBR rendering (since ambient lit surfaces have different reflections to direct lit surfaces).
Following on from this is to
reduce the directional lighting by adjusting the object's normals. This can allow you to change how the object appears to be lit (ie does the object act as if it is simply pointing upwards, rather than horizontally), but going too far with this can cause issues, such as it appearing too bright or too dark compared to surrounding objects. Finding the balance can be hard, but can produce helpful results.
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Another is camera facing planes. This is used for SpeedTrees for their 'billboard' lowest LOD, and for leaf planes on some SpeedTrees up close. Unfortunately there's no option to use this outside of SpeedTrees. However camera facing planes can be extremely distracting on larger objects up close, as they all rotate to face toward the camera all the time (so as you move, the trees rotate/move in sync with you). Even on leaf planes on SpeedTrees it can sometimes be distracting IMO, but it is less so than the entire tree doing this. The 'JVC-BB' trees are an example of an entirely camera facing tree, and show mostly how this works (including issues with it rotating in the wrong axis).
Effectively this brings us to the fact that billboards are not natural or realistic objects, and in effect are going to work poorly the more realistic you make the rendering in the game. This leads to the need to move away from billboards, as has been occurring for the most part in Trainz. There are, of course, some object types that can benefit from billboards, in particular smaller bushes/shrubs/etc where the flatness is going to be less obvious, and of course they will be a necessity in the lower LODs of otherwise 3D objects.
Unfortunately this does mean that there needs to be a move toward 3D trees, either manually modeled (as some members have done over the last 11 years), or created with SpeedTree or other similar resources. Some tree generation tools may allow you to import a modelled/textured tree into Blender or 3DSMax, where you can then lower the poly count, and then create LODs for it.
That said, all is not lost. The trees that Tony mentioned are all TANE or TRS19 standard SpeedTrees, and work quite well from my experience. Not every tree will be suited to every route. And some creators have seen some good results mixing select billboard trees with SpeedTrees to fill out forests, especially beyond the initial tree line.
IMO it's probably also worth contacting creators to see if they will allow you to reskin their released SpeedTrees. Some may have a 'close enough' shape for a different type of tree by simply changing the bark textures and the leaf textures; you'd need to play with the colours in the billboard to match as well, but it doesn't need to be exact in most cases. Even making the leaf and/or bark textures lighter or darker can create new variants that may suit different environments better.
It's also not impossible to create seasonal variants from otherwise non seasonal trees, since seasons can be in their own individual folders. Although not as efficient, simply masking out the leaves in the alpha channel of a 'winter' variant of a tree can make a winter version without needing a new model.
Unfortunately it's not possible for N3V to make most of the content for Trainz. Art man hours are costly, and as such N3V does need to focus our time where it will get the most value. At times this has been foliage, but that will change depending on what is in development/planned/etc. For the most part, it is up to the community to development the majority of content, however N3V has worked with members of the community on various content projects, however unfortunately only a limited number have done this in relation to foaliage. However if members of the community were interested in working with N3V to develop further foaliage, they should contact the team to discuss this.
I know this isn't necessarily what people want to hear, but as a route builder and 3D artist, this isn't a simple issue with simple solutions. Trees, like I said, are one of the most difficult object types to get right in modern games.
Regards
Zec
this is the thread,
https://forums.auran.com/trainz/sho...e-future-of-Trees-and-shrubs-for-Trainz/page4
We've made zero progress on this front in the past THREE YEARS , but I did learn from Clam 1952 how it mitigate the lighting problem in 2019 with the jvc /minky trees by revisiting the old thread.
once again , Malcolms expertise is sorely missed.
