Warn when a 3D shockwave model has no glow map (#7795)

Check each 3D shockwave model when it is loaded and warn if none of its textures has a glow map. The check is skipped when glow maps are disabled, since they are not loaded then.

Co-authored-by: Claude Opus 5 (1M context) <[email protected]>

code/weapon/shockwave.cpp

@@ -9,6 +9,7 @@
 
 #include "weapon/shockwave.h"
 #include "asteroid/asteroid.h"
+#include "cmdline/cmdline.h"
 #include "gamesnd/gamesnd.h"
 #include "globalincs/linklist.h"
 #include "io/timer.h"
@@ -577,6 +578,17 @@ int shockwave_load(const char *s_name, bool shock_3D)
 			Shockwave_info.pop_back();
 			return -1;
 		}
+
+		// glow maps are only loaded when enabled, so only check then
+		if (Cmdline_glow || Fred_running) {
+			auto pm = model_get(si->model_id);
+			bool has_glow = std::any_of(pm->maps, pm->maps + pm->n_textures, [](const texture_map &tmap) {
+				return tmap.textures[TM_GLOW_TYPE].GetTexture() >= 0;
+			});
+
+			if (!has_glow)
+				Warning(LOCATION, "3D shockwave model '%s' has no glow map.  For a 3D shockwave, the glow texture typically carries the animation.", si->filename);
+		}
 	} else {
 		si->bitmap_id = bm_load_animation( si->filename, &si->num_frames, &si->fps, nullptr, nullptr, true );