Looking through all places in the scripting API where `l_Object.Set()` is called, here is one where we might want to know about the object's breed.
(Normally we would return the result of `ade_set_object_with_breed()`, but the `testLineOfSight_internal()` function has multiple return arguments.)
Several locations in the code (notably `ai_info` and `waypoint_h`) previously stored pointers for waypoints and waypoint lists that need to be valid for more than one frame. Since both waypoint lists and waypoint paths may change size, resulting in vector reallocation, the information should be stored as indexes instead.
Fixes#6353.
This refactors the object_h struct to store objects as indexes rather than pointers. This is a prerequisite for making the collection of objects dynamic in the future. See also #6100.
Follow-up to #5800 and #5829.
To enforce type safety for arrival and departure locations, this converts them to enum classes. Various casts are added when appropriate to convert between the indexed and enum values.
This allows the skybox orientation and alpha to be accessed and changed through Lua virtvars, and also adds a sexp to change the alpha.
Unfortunately, changing the alpha has no perceptible effect on the skybox. This will need the attention of a graphics coder to figure out what might need updating.
Turn `Parse_names` into a vector and add SCP_string overloads of ship registry functions. Refactor calling code to use registry as appropriate. Remove an unused overload of `mission_parse_get_parse_object`.
* add extra ways to modify background elements in missions
This adds Lua API methods for getting suns and bitaps by index, as well as modifying their scale and position. This removes the need to completely add and remove a background element that only needs to be modified.
* big pruning of (int) casts
The `mn.createWeapon()` function takes an optional group ID for weapons that share lighting, but the internal `weapon_create_group_id()` function was never exposed to the API. This adds that.
When fireballs were made dynamic in 609ed4ed94, the `MAX_FIREBALLS` #define lost any relationship to the fireball collection. This removes it and also correctly specifies the size of the fireball collection.
This fixes a CTD when accessing items in `mn.Fireballs` via script.
When iterating through various object collections, check for the should-be-dead flag to avoid returning objects that are on the verge of being deleted.
Separately, this adds the `isExpiring` function to check for should-be-dead objects.
This PR also makes object iteration consistent across all object types, both to reduce code duplication and to ensure that the length and iteration are done using the same algorithm. Furthermore, if the number of should-be-dead objects is nonzero, the Lua array count for that frame will be different from the internal array count for that frame.
Fixes#5034.
Allow `mn.sendMessage` to send from a ship source, not only a string source, by allowing the ship object to be specified as the first argument. Also add `ship:sendMessage` which is a more streamlined version of the same thing.
Adds gravity! Applies on a per-mission basis, and weapons, ships, debris, and asteroids now have a configurable "gravity const" which multiplies the effect of gravity on them, by default everything except debris is 0 (meaning no effect even when the mission has gravity). AI and the lead indicator will also lead for ballistic trajectories as well, given a gravity-affected weapon. No FRED support or gravity direction control yet, to come in later PRs.
Birk Magnussen