On Thu, May 16, 2013 at 8:58 AM, Vivian Meazza wrote: > I'm rather surprised that you can't see the black outline around the trees. > It's around all of them, but is more or less visible according to the range > and angle of incidence. It is also the cause of the "spike" arising from the > centre of the trees. > > The proximate cause of the black outline is > <alpha-to-coverage>true</alpha-to-coverage>. Commenting out techniques 4 and > 9 in the tree effect removes all black artefacts.
There's a bug in the <predicate> for technique 4. It should only be enabled if you have ARB_multisample, but is incorrectly being enabled if you have shader language 2. I've got a fix for this that I've still to push. However, I think this issue predates my recent tree changes, though they may have exacerbated them. Were you seeing black borders around the trees before I started messing around with them recently? My system supports ARB_multisample, and IMO it provides quite a good effect at normal tree viewing distances. I'm slightly surprised that Thorsten's new system doesn't support this, as evidenced from his screenshots. Interestingly, when I disable technique 4, I start seeing the black outlines. Evidently there some very GPU-specific things going on here. On the plus side, I can at least reproduce the issue! I _do_ have a good fix for the black outlines in general, and I've modified the current textures to use it. I just need to push it - hopefully tonight. > While alpha-to-coverage is > intended for dense foliage or grass, I'm not sure that it is appropriate for > our trees as presently drawn and textured. I think you are right to try to > go back to the square texture. I hope that you can find a fix for this - Unfortunately modifying the mipmap didn't help. Partially disabling mipmaps by setting "nearest" meant that trees in the medium-far distance look very pixelated and artificial, and I've been unable to get the mipmap alpha channel to work. > know how difficult it is to fix a bug that you can't yourself see. In the > meantime should we consider reverting to the previous scheme in fgdata while > you come up with a fix? Here. I've adjusted the bleed margins and commented > out the relevant techniques, which produces nice trees. Let me check in the stuff I've done so far once I run a couple more tests this evening. That should fix the issues you are seeing. However, that still leaves us with very long, thin, textures as I can't see a way to go back to the square textures without causing the black hats. If we want to stay within a total texture size of 4096, the long, thin texture limits us to a maximum individual tree texture of 128x256, as there are now 32 textures in a typical sheet (8 trees, each in summer, summer+snow, winter, winter+snow variants). I think that a 128x256 texture for an individual tree isn't quite enough. While we don't need to go bird-spotting, it's not unreasonable to expect the tree to look good if it fills the screen. So, I think we have the following options: 1) Forget the whole thing. Revert back to the previous model of having one texture for summer and one for winter, no support for snow-covered trees. I'd still commit changes to fix the black outlines and technique=4, so the effort won't have been completely wasted. With a 4096 texture sheet limit we'd be able to have 512x1024 individual trees. 2) Support dynamic changing of snow-cover on trees, but not season changes. This means that to see a winter deciduous tree one would need to change the season and reload the scenery, loading in the winter material definitions which would include both the tree texture and general ground textures. Thorsten R. - what are your plans for ALS support for winter? I think you currently use the summer materials, correct? This would allow 256x512 individual trees. 3) Support dynamic changes of season, but have no support for snow-cover on trees in the texture itself. This is my probably my preferred option. While having snow-covered trees is nice, the actual circumstances when it occurs are fairly minimal as the snow is blown off the trees by the wind. This would allow 256x512 individual trees. 4) Accept the limitation of 128x256 individual tree textures. Let me know what you think. -Stuart ------------------------------------------------------------------------------ AlienVault Unified Security Management (USM) platform delivers complete security visibility with the essential security capabilities. Easily and efficiently configure, manage, and operate all of your security controls from a single console and one unified framework. Download a free trial. http://p.sf.net/sfu/alienvault_d2d _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
