Problems with Network Battle 02 on Raspberry Pi

[bbosen]

There is an important but subtle bug in "Network Battle 02" on the Raspberry Pi that was just discovered. It cannot be seen when just one player is participating, or if ALL participating players are using the Raspberry Pi. However, in a mixed environment where some players are using Raspberry Pi and others are using Ubuntu or one of the more traditional desktop LINUX distros, the terrain altitudes do not match.

Long ago, developers discovered that the Raspberry Pi does not render the desert terrain properly. Accordingly, although all of the other desktop LINUX distros are using the desert terrain, the Raspberry Pi has been using the same altitude map rendered through mountain terrain logic with a very dry climate and dry lakebeds for this mission,. We have long wanted to fix that mismatch, but it is primarily cosmetic and it's not as important as the newly discovered problems, which relate to terrain altitudes: The terrain altitudes of Raspberry Pi computers average almost 300 feet lower in Network Battle 02 than the corresponding terrain altitudes seen by players using other versions of LINUX.

This is especially distracting at Network Battle 02 airfields: Raspberry Pi pilots see Ubuntu pilots and others "landing" and "taxiing" about 300 feet above their airfields (when stopped, they just seem to hover there)! Pilots flying Ubuntu or other desktop distros see Raspberry Pi pilots suddenly drop down about 300 feet as soon as they fly off of runways, and they tend to skitter along the ground or 300 feet closer to the ground than they ought to.

This bug is present in all Raspberry Pi versions of LAC up thru version 8.58 and 8.59 as published at the time of this writing on 12mar2022.

Accordingly, we want to figure out why the Raspberry Pi cannot render the desert terrain as it is used in Network Battle 02, and then we will take whatever steps may be necessary to make it work on Raspbian like it does on the other LINUX distros. At that point Raspberry Pi pilots ought to see that mission in a manner that better matches what pilots of other LINUX platforms see, and terrain/airfield altitudes ought to match up as expected!

[bbosen]

Update: An experimental new version of LAC, designated 8.60, is now undergoing alpha testing in our labs. It was written only for the benefit of the Raspberry Pi, and on all other platforms, its features exactly match version 8.58. On the Raspbian operating system, however, the following differences will be seen in Network Battle 02:

1: The "mountain/dry lake" terrain previously used in Raspbian's version of "Network Battle 02" has been replaced with the same "desert" terrain that has long been used on other LINUX distros. The general appearance is nicer, and it really does look a lot like the North African desert that has always been intended for this mission.

2: Terrain altitudes still don't exactly match those seen on other (non-Raspbian) platforms, We took compensating steps to ensure interoperability between Raspbian and non-Raspbian platforms: Upon receipt of any incoming data packet from a network peer, Raspbian-hosted copies of LAC always subtract 300 feet from the received altitude. On the other hand, upon transmission of an outgoing data packet, Raspbian-hosted copies of LAC always add 300 feet to the transmitted altitude. This ensures that the apparent visual altitudes always look correct in flight and on runways, regardless of the Raspbian or non-Raspbian origin and interpretation of those packets.

3: When Raspbian renders the desert terrain, certain terrain features are rendered differently from other platforms. In general, terrain "erosion" is more extensive. The tops of mountains are more rounded, and the valleys between hills and peaks are more filled with debris. Cliff walls aren't quite as steep. In most circumstances and at normal flight altitudes, these changes are subtle and of little consequence. However, if a Raspbian-hosted pilot is following an Ubuntu-hosted pilot that is flying very very very low down in the terrain, each of the two pilots might experience conflicting visual situations: The Ubuntu-hosted player might see himself flying a few feet above the ground, while the Raspbian-hosted player might see him colliding with the surface or even disappearing slightly below the surface. Unfortunately we have not found any solution to this problem, but so long as the Raspbian-hosted players are aware of it, it is of little consequence.

We expect to publish this new version 8.60 of Linux Air Combat for use on the Raspberry Pi sometime in late March or early April of 2022, whereupon Raspberry Pi players should be able to enjoy "Network Battle 02" with improved visual effects and much better interoperability among non-Raspbian players.

[bbosen]

Linux Air Combat Version 8.60 is now available for Raspberry Pi download from the "Files" section of our pages at sourceforge.net according to the established pattern. With that version, Network Battle02 now displays the Desert Terrain on the Raspberry Pi as anticipated in the prior postings of this thread. It looks better than ever on the Raspberry Pi. (Version 8.60 is ONLY published for the Raspberry Pi.)

[bbosen]

Update 06Feb2023:

As indicated above, newer versions of LAC (since 8.60) on the Raspberry Pi faithfully display aircraft at appropriate altitudes, even in the Desert terrain.

At the time of this writing, the current version of LAC is 8.95 for all platforms, including the Raspberry Pi.

HOWEVER, in the Desert terrain of Network Mission 02, some of the "Replay Blokes" were recorded before version 8.60, and some of those recorded Blokes were actually flying Raspberry Pi versions that did not properly match altitudes. Accordingly, when flying in Mission 02, you may still see some Replay Blokes flying altitudes about 200 feet higher than intended. This is of small consequence most of the time and really does not affect air-to-air combat, but it looks really odd when those airplanes land, because they "hover" about 200 feet above the airfield. All of the old recordings of Replay Blokes suffering from this odd anomaly are flying for the RedTeam, so this funny bug is generally seen only by other RedTeam players spending time parked or taxiing on the runway of the RedTeam HQ airfield of Network Mission 02.