In 2006, Resident Gene Replacement managed to tweak the viewer in a way that allowed him to create these objects despite their limitations, until Linden Lab fixed the security hole some time later. The mega prims were distributed and spread quickly across the grid, since Residents found many ways to use them in their builds. While Linden Lab didn't ban the objects completely, their policy was to return them if they were a "nuisance". In a Town Hall discussion at December 20th 2006, Linden Lab announced that they were going to allow the use of mega prims on private estates. After open sourcing the viewer, another bug exploit allowed the creation of mega prims for a limited time. Residents took the chance to create a variety of these objects in many different sizes, even those which covered multiple regions completely. Linden Lab announced and discussed plans on using methods to prohibit the use of mega prims greater than 64.000m in one dimension, but then decided to only limit them to 256m, since they found legitimate use for the 256m prims (for example in horizons and skies).
Problems with Mega Prims
Problems with mega prims are obviously related to their huge size. They can reach far beyond parcel borders and therefor disturb neighbours with their presence. Residents might not even recognize that it is a mega prim which is hindering them, since they might be inside the mega prim and therefor won't be able to see it.
There are also reports that the graphics engine wouldn't be able to work well with prims larger than 256 meter in any dimension.
Although there is a persistent rumour that mega prims would be a cause for lag, they can in fact be used to reduce lag. In large builds, by using a mega prim instead of multiple regular prims (for a wall, a floor, etc), the number of faces which need to be drawn by the viewer (or, depending on how "smart" is your graphic driver, the number of occlusions to calculate so to avoid drawing hidden faces) can be reduced dramatically.
Building with Mega Prims
Mega prims can be edited like any other prim despite that it's not possible to edit their dimensions. The attempt to edit the dimension of a mega prim will result in all sides of the mega prim which are greater than 10m instantly switching back to the regular 10m limit. To be able to edit and move some huge mega prims, it is suggested to access the advanced menu (press - - - ) and to toggle "Limit Select Distance" off, as well as "Disable Camera Constraints" on.
In order to support builders who'd like to use mega prims, many Residents made them and are providing them for free. You can find many mega prim packages inworld or at SL webstores.
Future of Mega Prims
- Allow parcel owners/managers to move (or maybe just return) objects that overlap their parcels.
- Provide UI feedback to the Resident when moving their objects, indicating whether they overlap neighboring parcels.
- Maybe provide real-time enforcement of parcel permissions. That is, allow parcel owners to set a paranoid bit “I don’t want anyone, or these specific people, from putting stuff on my parcel”
He noted that "once that is done then perhaps we will allow you to make prims/objects as large as you want as long as they fit on your parcel."