Adds Props as a new object type #6836

MjnMixael · 2025-07-14T18:11:25Z

This PR adds Props as a distinct new object type. Props work very similarly to ships in most cases but there are some key assumptions that make them unique:

Props cannot move
Props are not interactable except for being collided with

Props are meant to be scenery, set pieces, decoration, or even objects rendered by Lua in the UI only. Props do not take up ship slots and are not limited. Props are created in FRED using the new second dropdown with ctrl-shift-click instead of just ctrl-click

Props have a basic set of flags to start:

No Collide
No FRED
No Lighting

Props have a basic set of sexps to start:

add-to-collision-group-prop
remove-from-collision-group-prop
get-collision-group-prop
prop-create
prop-vanish

Props have basic Lua support including collision hooks and table indexing with a standard set of members and methods. Props are also a valid type for Lua SEXPs. Props are viewable in the F3 Lab as well. Props have stubbed in support for @BMagnu animation system and glowpoints but both are inactive for now.

Props.tbl is modular with -prp.tbm. It supports both +nocreate and +remove. Props can be categorized with colors for easy browsing in FRED. A sample table looks like this:

#PROP CATEGORIES

$Name: Planets
+Color: (0, 125, 0)

#PROPS

$Name: Planet-Antares1
	$POF file: planet-antares1.pof
	$Closeup_pos: 0.0, 0.0, -6000
	$Closeup_zoom: 0.5
	$Detail distance: (0)
	$Category: Planets
	$Custom Data:
	+Val: Category Between the Ashes
	$Custom Strings
	$Name: MapText
	+Value: -1
	+String: The first planet of the Antares System.
	$end_custom_strings

#END

Many thanks to @BMagnu and @Baezon for the assistance in various places of this PR, especially with collisions.

Fixes #4727

code/object/collideshipweapon.cpp

code/object/objcollide.cpp

BMagnu

Great work.
A few small things, otherwise this is pretty much there.
Just as a list of ToDo you mentioned in the code and that I can think of that should be done in future PRs, as a reference here:
Modelanimation support
Multithreaded collision support
Possibly support as a permanent particle host (think something like a Volcano spewing smoke)

code/lab/dialogs/lab_ui.cpp

code/lab/manager/lab_manager.cpp

code/mission/missionparse.cpp

code/model/modelrender.cpp

code/object/collideshipweapon.cpp

qtfred/src/mission/management.cpp

code/prop/prop.h

code/prop/prop.cpp

MjnMixael · 2025-10-17T15:19:40Z

Great work. A few small things, otherwise this is pretty much there. Just as a list of ToDo you mentioned in the code and that I can think of that should be done in future PRs, as a reference here: Modelanimation support Multithreaded collision support Possibly support as a permanent particle host (think something like a Volcano spewing smoke)

And full QtFRED support which I'll get to once I finish rewriting sexp tree to be shared between FRED and QtFRED.

BMagnu

Wanted to comment on SEXP ergonomics when I saw the model_instance thing, so I'm giving this a short look-over again. Should all be fairly simple, but better to root out anything now than after it's merged

BMagnu · 2026-01-13T15:15:23Z

code/object/objectsort.cpp

 	} else if (obj->type == OBJ_RAW_POF) {
 		model_num_a = Pof_objects[obj->instance].model_num;
+	} else if (obj->type == OBJ_PROP) {
+		model_num_a = prop_id_lookup(obj->instance)->model_instance_num;


Wait a minute, should this not be model_num rather than model_instance_num here?

This is prop object, which doesn't have model_num. model_instance_num looks to be equivalent.

BMagnu · 2026-01-13T15:15:28Z

code/object/objectsort.cpp

 	} else if (other.obj->type == OBJ_RAW_POF) {
 		model_num_b = Pof_objects[other.obj->instance].model_num;
+	} else if (other.obj->type == OBJ_PROP) {
+		model_num_b = prop_id_lookup(other.obj->instance)->model_instance_num;


BMagnu · 2026-01-13T15:20:26Z

code/parse/sexp.cpp

+	{ "add-to-collision-group-prop",	OP_ADD_TO_COLGROUP_PROP,				2,	INT_MAX,	SEXP_ACTION_OPERATOR,	},	// MjnMixael
+	{ "remove-from-collision-group-prop",	OP_REMOVE_FROM_COLGROUP_PROP,		2,	INT_MAX,	SEXP_ACTION_OPERATOR,	},	// MjnMixael
+	{ "get-collision-group-prop",		OP_GET_COLGROUP_ID_PROP,				1,	1,			SEXP_ACTION_OPERATOR,	},  // MjnMixael


Playing around with this, as a slight ergonomic improvement, is it not possible to make the original collision group sexps just accept ships and props?

Iirc the original sexps are tuned pretty specifically for ships and it would require a new sexp_tree type (ship or prop) I think. Honestly this PR has been sitting so long I don't really remember how it works under the hood anymore.

Ok, yes I looked at this. This requires significant overhead just for the one combined sexp to work. You'd need a new Sexp Tree type, OPF_SHIP_PROP, and all the extra code that requires. You'd need to do that for both FRED and QtFRED. Then you'd need to change the ship versions of these sexps to accept OFP_SHIP_PROP instead if just OPF_SHIP and adjust the sexp code to have two paths. This also requires adjusting all the error checking for these sexps to be able to return a new "invalid ship or prop" error type.

This would be a user-facing improvement for sure but I, quite honestly, don't want to do all that work just for these barely used sexps. If there were other more common sexps that could benefit from OPF_SHIP_PROP then it might be more justified.

BMagnu · 2026-01-13T15:25:05Z

code/parse/sexp.h

@@ -1479,6 +1488,7 @@ struct wing;
 // Goober5000 - stuff with caching
 // (included in the header file because Lua uses the first three)


This comment should probably be updated to 4

BMagnu · 2026-01-13T15:26:51Z

code/parse/sexp/LuaSEXP.cpp

+		auto ship_entry = eval_prop(node);
+
+		// if this is a shipname type, we want the name of a valid ship but not the ship itself
+		// (if the ship is not valid, return an empty string)
+		if (argtype.first == "propname") {
+			return LuaValue::createValue(_action.getLuaState(), ship_entry ? ship_entry->prop_name : "");
+		}
+
+		if (!ship_entry || (ship_entry->objnum >= 0)) {
+			// Name is invalid
+			return LuaValue::createValue(_action.getLuaState(), l_Prop.Set(object_h()));
+		}
+
+		auto objp = &Objects[ship_entry->objnum];


Lots of this is called ship, but should probably be called prop, both in comments and variable names

BMagnu · 2026-01-13T23:46:55Z

code/lab/dialogs/lab_ui_helpers.cpp

+SCP_string get_prop_table_text(const prop_info* pip)
+{
+	char line[256], line2[256], file_text[82];
+	int i, j, n, found = 0, comment = 0, num_files = 0;


If we're already doing a round 2 here:
Is it possible to consolidate this with the function above, as they basically do the same thing?

Depends on where you want to draw the line. Right now, iirc, this matches the code structure that ships do. If I update this are you going to want me to update ships also?

Looking at this, I'd rather not for now. This whole file could use consolidation and cleanup. However, this Props PR does a ton of changes already. I'd rather keep the change here as additive and later on someone can consolidate get_weapon_table_text, get_ship_table_text, get_asteroid_table_text, and get_prop_table_text as much as makes sense.

…ctly

MjnMixael force-pushed the add_prop_object_type branch from 41df668 to 9119837 Compare July 14, 2025 19:14

wookieejedi added the feature A totally new sort of functionality label Jul 14, 2025

MjnMixael force-pushed the add_prop_object_type branch 2 times, most recently from 560ef58 to 56e68c4 Compare July 18, 2025 20:04

MjnMixael force-pushed the add_prop_object_type branch from 56e68c4 to 6d47939 Compare July 24, 2025 16:09

Baezon reviewed Jul 24, 2025

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MjnMixael force-pushed the add_prop_object_type branch from 5053b91 to 1027a9f Compare September 10, 2025 01:37

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BMagnu requested changes Oct 17, 2025

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MjnMixael force-pushed the add_prop_object_type branch from 92fecb8 to 27a65e3 Compare October 17, 2025 14:26

BMagnu added the Waiting for Stable Marks a pull request that is to be merged after the next stable release, due to a release cycle label Oct 18, 2025

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MjnMixael force-pushed the add_prop_object_type branch from e4e745c to 1ae73c7 Compare January 30, 2026 18:50

MjnMixael and others added 26 commits January 30, 2026 12:51

First draft of prop object type

fc05097

Add prop editor dialog in FRED

5cd6098

prop sexps

538cfd2

lua table prop support

abd5c1b

lab support

471202d

lua mission access to props

ad08259

prop collision support

e61c444

use std::optional so the object->instance id is always valid

27f7071

allow props to block suns

29e4038

minor cleanup and remove arbitrary limit. Still limited to 500 objects.

9ed5484

Sort props by category

daa13a2

cleanup

3fce818

implement collision hooks

b07f166

parse prop flags and further ensure props are inited and closed corre…

6de979b

…ctly

Add Cyborg's multi suggestions

379db25

fix missing header

4a73374

add props to empty slots if available

ea0989b

add multi signature

f136a58

fix rebase issues and match collisions to the new multithread style

7488d8f

appease Clang the Conquerer

dbf378b

save/parse mission prop classes by name

cb18e57

Clean up comments and finish TODOs

b0b2e1f

fix string errors

43f0c85

clang wants this to be static now

a82f39f

address feedback

1ae73c7

address feedback

3297ab4

MjnMixael added this to the Release 26.0 milestone Jan 30, 2026

		@@ -1479,6 +1488,7 @@ struct wing;
		// Goober5000 - stuff with caching
		// (included in the header file because Lua uses the first three)

Adds Props as a new object type #6836

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Adds Props as a new object type #6836

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