The attachment needs 3 vectors: a position vector, a direction vector from that position, and then an "up" direction from the direction vector, which is the orientation vector. Making the analogy with a key and a lock, the position vector tells where the lock is, the direction vector tells the direction from which the key will be inserted (changing the sign of this vector will switch between putting the key from inside or outside of the door), and the orientation vector tells the rotation of the key (some go in upright, others sideways).
This all assumes the trunnions in the mesh have the correct distances between them, and they "place" the payload inside the 90 inch payload volume.
The attachment is placed in the keel trunnion (the one on the bottom). So the distance from the longeron trunnions (the ones on the sides) to the attachment in the keel is 414.05-305.025=109.025 inches or 2.769235 meters. Find the coordinates of the longeron trunnions and subtract it from 2.769235 and that's the up/down position.
The sideways axis coordinate is 0.
Longitudinally, the 3 trunnion locations need to have their relative distances as a multiple of 3.933 inches, or 0.0998982m. From there, the last coordinate of the attachment position is found, as well as the "distances" between the PLIDs (e.g., the fwd longeron is 10 PLIDs ahead of the keel PLID, and 15 ahead of the aft PLID).
The direction vector, is "down" from the keel, so the coordinate of that axis is 1 or -1, and the others are 0.
The orientation vector should point in the direction of the part that is going to be forward in the PLB, so the longitudinal axis coordinate is 1 or -1, and the others 0.
Now with the attachment defined, all that remains is placing the payload in the PLB by defining the PLIDs in the Mission Editor. One can always pick at random if it is a custom payload, but for real payloads the idea is to use the actual numbers. They can be found in some mission payload bay diagrams that contain the Xo coordinates, which can be easily translated to the PLID number with a table in the document gattispilot posted a few days ago. When those diagrams aren't available, one can always find a photo of the PLB and count slots in the bridge fittings, which should be well placed in SSV to match the real thing.
..and that should be it.
This all assumes the trunnions in the mesh have the correct distances between them, and they "place" the payload inside the 90 inch payload volume.
The attachment is placed in the keel trunnion (the one on the bottom). So the distance from the longeron trunnions (the ones on the sides) to the attachment in the keel is 414.05-305.025=109.025 inches or 2.769235 meters. Find the coordinates of the longeron trunnions and subtract it from 2.769235 and that's the up/down position.
The sideways axis coordinate is 0.
Longitudinally, the 3 trunnion locations need to have their relative distances as a multiple of 3.933 inches, or 0.0998982m. From there, the last coordinate of the attachment position is found, as well as the "distances" between the PLIDs (e.g., the fwd longeron is 10 PLIDs ahead of the keel PLID, and 15 ahead of the aft PLID).
The direction vector, is "down" from the keel, so the coordinate of that axis is 1 or -1, and the others are 0.
The orientation vector should point in the direction of the part that is going to be forward in the PLB, so the longitudinal axis coordinate is 1 or -1, and the others 0.
Now with the attachment defined, all that remains is placing the payload in the PLB by defining the PLIDs in the Mission Editor. One can always pick at random if it is a custom payload, but for real payloads the idea is to use the actual numbers. They can be found in some mission payload bay diagrams that contain the Xo coordinates, which can be easily translated to the PLID number with a table in the document gattispilot posted a few days ago. When those diagrams aren't available, one can always find a photo of the PLB and count slots in the bridge fittings, which should be well placed in SSV to match the real thing.
..and that should be it.