The EM46 mod (Enhanced M46) was a modification I created for the Battlefield Vietnam engine. The introduction of hooks to the helicopters was a great addition to the game; however, with this introduction, I felt it was somewhat arbitrary that artillery could not be emplaced dynamically. The original M46 artillery piece was a static mesh akin to the anti-air emplacements in the original 1942 engine. I felt it would enhance the game if the M46 could be packed and moved by hand or airlifted by helicopter. The engine wasn't exactly mod friendly, but I had spent considerable time working in the BF42 engine and the BFV engine did not have significant changes so I was able to put this together in about two weeks of intensive work in 3dMax, Notepad and the community packing tools.

The concept was that the M46 needed to be a stable firing platform if the gun was deployed and it needed to be maneuverable when packed.

EM46 unpacked

I decided to use the unused pitch controls to manage the packing and unpacking of the gun (same method was used to raise and lower the doors on the LCVP) which would allow standard controls for movement and the additional controls for the pack/unpack procedure.

EM46 packed

First, the original mesh had to be extracted from the game library and made compatible with Max. Thankfully, there were good community tools at this time to be able to do this. Once the mesh was accessible in Max, I modified it by creating the three derivative meshes, the gun system and the two spade breaks as well as the collision meshes. I was able to pack up the geometry and add it into the game library. I then added the necessary code to the object definition to make the gun a vehicle and added all the parts that can't be seen in game, springs and wheels. The final design had five wheels and I think four contact springs. The wheels were articulated to contact the ground and the springs were articulated out of contact with the ground by the pack procedure. The unpack procedure reversed the process. These elements are invisible, except for the two transport wheels, in the implementation; although, I produced a second mod, the XM46, which made these elements visible for debugging and fun.

There was a lot of experimentation as to how the system should behave when moved. The final configuration of the wheels used five wheels, the two visible ones and three invisible ones, in an arrangement similar to a tractor trailer, two sets of wheels mounted in parallel close together, with the fifth wheel set at the point of the spade breaks when packed. The fifth wheel was the steering mechanism and had a very slow yaw rate so as to make man porting somewhat ungainly as it was unreasonable for one person to push such a heavy artillery piece, at least well or fast. The end result was satisfactory except the gun could still be fired while packed; although, because it was now on wheels, the recoil made it extremely hard to zero on a target and placing any rounds on target was next to impossible in this configuration.

pushing the EM46

The movement of the spade breaks gave a visual cue to the player as to what configuration the EM46 was in. If the breaks were fully extended, then the player knew that the system was a stable firing platform. If the spades were in any other configuration, then the gun may shift due to recoil at varying degrees. The articulated parts were implemented in such a way as to only be fully stable in the unpacked mode. The first movement in the packing procedure lifted the stabilization springs out of ground contact and the system could respond wildly if fired in an other partial configuration. The system also would not be man movable unless fully packed. Working within the engine constraints caused a lot of hairpulling and recompiling to get the system as good as it could be.

EM46 fully unpacked

EM46 partially packed

The real impetus behind the mod was the addition of hooks to helicopters. The EM46 could be airlifted in any configuration. The primary need for man porting was the need to orient the system once it had been airlifted. Man porting was never intended as a primary means of transporting the gun around the battlefield.

Airlifting the EM46 was simple, hook and lift

The gun could then be transported anywhere on the battlefield using a helicopter. The simplistic approach to artillery irked me somewhat since throughout the history of cannon, they have been a pivotal aspect of warfare. In the official game, the enemy always knew where the guns were located due to the static mesh implementation. By moving the guns, the advantage to the armored campers could be negated. The game often simply centered around bypassing the static emplacements and parking a tank in the enemy spawn. By dynamically moving the guns, some of the more poorly designed maps could be significantly enhanced and the EM46 could actually be used strategically instead of acting as scenery.

Cut this road and cut off the armored campers

In the mod, the APC's had hooks added to them as well. This allowed the M113 to tow the artillery piece about the battlefield. The towing was less capable than airlifting due to some technical reasons with the hook implementation. The grapple point had to remain centered, so the APC would actually hook the middle of the EM46 instead of the more logical/realistic grapple point at the tip of the spades. This made the towing procedure somewhat ungainly as the gun might turn during the tow and would likely flip as a result. This was very frustrating when one towed a gun all the way across the map only to have it tip over and explode before it was used. This is the main reason five wheels were selected instead of a tricycle configuration. With two pairs of parallel wheels, one pair aligned along the axis at the center of gravity and the other pair offset behind it, the system more naturally corrected itself and remained oriented properly in a forward tow; however, the solution wasn't perfect and there was still a high risk for the jackknife when backing up.

Towing the EM46 with the M113

The M46 could then be used in a highly unpredictable manner. Of course, this could have led to a new form of tardiness; however, the general fragility of the weapon and the exposed nature of the gun position was a deterrent to extreme exploiting. It did, however, have one of the most powerful guns in the game. There were always several M46s near the bases, but they were never in a position to defend against spawn camp. Just by being able to turn it around, these game elements would have been much more useful in defending from spawn camp.

An EM46 suppressing the Airfield. Note the repeated firing and absence of shifting for the stable unpacked mode.

Most importantly, the Enhanced M46 could be used tactically in some new and advantageous ways. It is general practice to camouflage gun positions to both hide the gun and to protect the crew. The map designs almost always emplaced the M46 in the most exposed positions imaginable. It was generally suicide to man one of the guns in either BF42 or BFV and rarely did players even use the elements unless presented with the perfect kill shot or gambling on the lucky first shot against a damaged enemy. There were perfect bunkers strewn about the maps for these artillery pieces and the designers never used them to protect the artillery. Many unwary, buttoned-up tankers could have been dispatched from ambush positions with either effective map design or direct engine support for portable AT artillery and these elements would not have gone unused as they did.

Superior and realistic AT emplacement

One thought may have been that these elements would be overpowered if used tactically in this manner. But by emplacing the artillery in the bunker the field of view was reduced significantly. The gunner really could only work with what was directly in the line of fire and would have needed a spotter to spring such a trap. So, it would also have encouraged tighter teamwork and in a game that was team oriented, the teamwork aspects were not heavily emphasized. Mostly, the game was a complex and chaotic form of deathmatch on random servers.

A limited FOV, but a well disguised ambush position along the armor approach

Development did not go without its hitches. Along the way, everything from screwing up geometry and UV mapping to forgetting to hide geometry in a build occurred. The XM46 mod grew out of the need to rigorously test the various designs and at this point, I was still a neophyte in Max.

An intermediate version of the mod. The four wheeled design was later improved with the final five wheel design. The helper wheels are visible.

A bad UV map. The edges of the texture are visible. It was corrected before release.

A bad build with all geometry centered. At least the UV map is fixed.

The AT unicycle.

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