Optimize UI model instance

code/graphics/2d.cpp

@@ -33,6 +33,7 @@
 #include "graphics/util/UniformBufferManager.h"
 #include "graphics/shadows.h"
 #include "io/mouse.h"
+#include "model/modelrender.h"
 #include "libs/jansson.h"
 #include "options/Option.h"
 #include "osapi/osapi.h"
@@ -2925,6 +2926,8 @@ void gr_flip(bool execute_scripting)
 		}
 	}
 
+	model_process_cached_ui_render_instances();
+
 	gr_reset_immediate_buffer();
 
 	// Do per frame operations on the matrix state

code/menuui/techmenu.cpp

@@ -25,6 +25,7 @@
 #include "lighting/lighting.h"
 #include "localization/localize.h"
 #include "menuui/techmenu.h"
+#include "model/modelrender.h"
 #include "missionui/missionscreencommon.h"
 #include "parse/parselo.h"
 #include "playerman/player.h"
@@ -213,7 +214,6 @@ static const char *Text_lines[MAX_TEXT_LINES];
 static int Cur_entry = -1;				// this is the current entry selected, using entry indexing
 static int Cur_entry_index = -1;		// this is the current entry selected, using master list indexing
 static int Techroom_modelnum = -1;
-static int Techroom_model_instance = -1;
 static float Techroom_ship_rot;
 static UI_BUTTON List_buttons[LIST_BUTTONS_MAX];  // buttons for each line of text in list
 
@@ -332,12 +332,6 @@ void techroom_select_new_entry()
 
 		Techroom_modelnum = model_load(sip, true);
 
-		if (Techroom_model_instance >= 0) {
-			model_delete_instance(Techroom_model_instance);
-		}
-		Techroom_model_instance = model_create_instance(model_objnum_special::OBJNUM_NONE, Techroom_modelnum);
-
-		model_set_up_techroom_instance(sip, Techroom_model_instance);
 
 		Current_list->at(Cur_entry).model_num = Techroom_modelnum;
 
@@ -348,10 +342,6 @@ void techroom_select_new_entry()
 	} else {
 		Techroom_modelnum = -1;
 
-		if (Techroom_model_instance >= 0) {
-			model_delete_instance(Techroom_model_instance);
-			Techroom_model_instance = -1;
-		}
 
 		Trackball_mode = 0;
 
@@ -393,11 +383,6 @@ void techroom_select_new_entry()
 				if (Techroom_modelnum >= 0) {
 					weaponLoaded = true;
 
-					if (Techroom_model_instance >= 0) {
-						model_delete_instance(Techroom_model_instance);
-					}
-					Techroom_model_instance = model_create_instance(model_objnum_special::OBJNUM_NONE, Techroom_modelnum);
-
 					// If this ends up being needed for weapon models, a weapon version
 					// of this method will need to be created. Should only be necessary
 					// if weapon models start having animations or other advanced model
@@ -611,6 +596,12 @@ void techroom_ships_render(float frametime)
 	model_clear_instance(Techroom_modelnum);
 	render_info.set_detail_level_lock(0);
 
+	int model_instance = -1;
+	model_get_cached_ui_render_instance(Techroom_modelnum, &model_instance);
+	if (Tab == SHIPS_DATA_TAB) {
+		model_set_up_techroom_instance(&Ship_info[Cur_entry_index], model_instance);
+	}
+
     if(shadow_maybe_start_frame(Shadow_disable_overrides.disable_techroom))
     {
         gr_reset_clip();
@@ -620,7 +611,7 @@ void techroom_ships_render(float frametime)
 		shadows_start_render(&Eye_matrix, &Eye_position, Proj_fov, gr_screen.clip_aspect, -closeup_pos.xyz.z + pm->rad, -closeup_pos.xyz.z + pm->rad + 200.0f, -closeup_pos.xyz.z + pm->rad + 2000.0f, -closeup_pos.xyz.z + pm->rad + 10000.0f);
         render_info.set_flags(MR_NO_TEXTURING | MR_NO_LIGHTING | MR_AUTOCENTER);
 
-		model_render_immediate(&render_info, Techroom_modelnum, Techroom_model_instance, &Techroom_ship_orient, &vmd_zero_vector);
+		model_render_immediate(&render_info, Techroom_modelnum, model_instance, &Techroom_ship_orient, &vmd_zero_vector);
         shadows_end_render();
 
 		gr_set_clip(Tech_ship_display_coords[gr_screen.res][SHIP_X_COORD], Tech_ship_display_coords[gr_screen.res][SHIP_Y_COORD], Tech_ship_display_coords[gr_screen.res][SHIP_W_COORD], Tech_ship_display_coords[gr_screen.res][SHIP_H_COORD], GR_RESIZE_MENU);
@@ -636,7 +627,7 @@ void techroom_ships_render(float frametime)
 
 	render_info.set_flags(render_flags);
 
-	model_render_immediate(&render_info, Techroom_modelnum, Techroom_model_instance, &Techroom_ship_orient, &vmd_zero_vector);
+	model_render_immediate(&render_info, Techroom_modelnum, model_instance, &Techroom_ship_orient, &vmd_zero_vector);
 
 	Glowpoint_use_depth_buffer = true;
 
@@ -1314,7 +1305,6 @@ void techroom_lists_reset()
 
 	model_free_all();
 	Techroom_modelnum = -1;
-	Techroom_model_instance = -1;
 
 	// This can be cleared immediately because there are no anims or bitmaps associated.
 	Ship_list.clear();

code/missionui/missionscreencommon.cpp

@@ -38,6 +38,7 @@
 #include "missionui/missionshipchoice.h"
 #include "missionui/missionweaponchoice.h"
 #include "mod_table/mod_table.h"
+#include "model/modelrender.h"
 #include "network/multi.h"
 #include "network/multi_endgame.h"
 #include "network/multimsgs.h"
@@ -1651,9 +1652,14 @@ void draw_model_icon(int model_id, uint64_t flags, float closeup_zoom, int x, in
 
 	Glowpoint_override = true;
 	model_clear_instance(model_id);
+	int model_instance = -1;
+	model_get_cached_ui_render_instance(model_id, &model_instance);
+	if (sip != nullptr) {
+		model_set_up_techroom_instance(sip, model_instance);
+	}
 
 	render_info.set_flags(flags);
-	model_render_immediate(&render_info, model_id, &object_orient, &vmd_zero_vector);
+	model_render_immediate(&render_info, model_id, model_instance, &object_orient, &vmd_zero_vector);
 	Glowpoint_override = false;
 
 	gr_end_view_matrix();
@@ -1669,7 +1675,8 @@ void draw_model_rotating(model_render_params *render_info, int ship_class, int m
 	if (model_id < 0)
 		return;
 
-	int model_instance = model_create_instance(model_objnum_special::OBJNUM_NONE, model_id);
+	int model_instance = -1;
+	model_get_cached_ui_render_instance(model_id, &model_instance);
 	if (!(flags & MR_IS_MISSILE) && SCP_vector_inbounds(Ship_info, ship_class)) {
 		model_set_up_techroom_instance(&Ship_info[ship_class], model_instance);
 	}
@@ -1953,9 +1960,6 @@ void draw_model_rotating(model_render_params *render_info, int ship_class, int m
 	}
 
 	shadow_end_frame();
-	if (model_instance >= 0) {
-		model_delete_instance(model_instance);
-	}
 }
 
 /**

code/missionui/missionweaponchoice.cpp

@@ -30,6 +30,7 @@
 #include "missionui/missionshipchoice.h"
 #include "missionui/missionweaponchoice.h"
 #include "model/model.h"
+#include "model/modelrender.h"
 #include "mod_table/mod_table.h"
 #include "network/multi.h"
 #include "network/multi_pmsg.h"
@@ -823,10 +824,9 @@ void draw_3d_overhead_view(int model_num,
 		Glowpoint_use_depth_buffer = false;
 
 		model_clear_instance(model_num);
-		int model_instance = model_create_instance(model_objnum_special::OBJNUM_NONE, model_num);
-		if (model_instance >= 0) {
-			model_set_up_techroom_instance(sip, model_instance);
-		}
+		int model_instance = -1;
+		model_get_cached_ui_render_instance(model_num, &model_instance);
+		model_set_up_techroom_instance(sip, model_instance);
 		polymodel* pm = model_get(model_num);
 
 		if (sip->replacement_textures.size() > 0) {
@@ -868,9 +868,6 @@ void draw_3d_overhead_view(int model_num,
 		batching_render_all();
 
 		shadow_end_frame();
-		if (model_instance >= 0) {
-			model_delete_instance(model_instance);
-		}
 
 		// NOW render the lines for weapons
 		gr_reset_clip();

code/model/modelrender.cpp

@@ -26,6 +26,7 @@
 #include "nebula/neb.h"
 #include "particle/particle.h"
 #include "prop/prop.h"
+#include "parse/encrypt.h"
 #include "render/3dinternal.h"
 #include "render/batching.h"
 #include "ship/ship.h"
@@ -35,6 +36,7 @@
 #include "weapon/weapon.h"
 
 #include <algorithm>
+#include <unordered_map>
 
 extern int Model_texturing;
 extern int Model_polys;
@@ -50,6 +52,108 @@ extern void interp_generate_arc_segment(SCP_vector<vec3d> &arc_segment_points, c
 
 int model_render_determine_elapsed_time(int objnum, uint64_t flags);
 
+SCP_unordered_map<cached_ui_render_instance_key, cached_ui_render_instance_entry, cached_ui_render_instance_key_hash>
+	Cached_ui_render_instance_cache;
+UI_TIMESTAMP Ui_render_instance_cache_last_processed_timestamp = UI_TIMESTAMP::invalid();
+constexpr int UI_RENDER_INSTANCE_CACHE_UNUSED_MS_GRACE = 100;
+
+size_t model_hash_subsystem_name_list_for_cache(const SCP_vector<SCP_string>& subsystem_names)
+{
+	if (subsystem_names.empty()) {
+		return 0;
+	}
+
+	SCP_vector<SCP_string> normalized_names;
+	normalized_names.reserve(subsystem_names.size());
+
+	for (const auto& name : subsystem_names) {
+		auto normalized = name;
+		SCP_tolower(normalized);
+		normalized_names.push_back(std::move(normalized));
+	}
+
+	std::sort(normalized_names.begin(), normalized_names.end());
+
+	size_t seed = 0;
+
+	boost::hash_combine(seed, static_cast<uint32_t>(normalized_names.size()));
+	for (const auto& name : normalized_names) {
+		boost::hash_combine(seed, hash_fnv1a(name));
+	}
+
+	return seed;
+}
+
+// Returns TriStateBool::TRUE_ if a new instance was created, TriStateBool::FALSE_ if an existing instance was returned,
+// or TriStateBool::UNKNOWN_ if there was an error (and model_instance_out will be set to -1 in this case)
+TriStateBool model_get_cached_ui_render_instance(int model_num, int* model_instance_out, size_t instance_data_hash)
+{
+	Assertion(model_instance_out != nullptr, "model_instance_out must not be null!");
+	if (model_instance_out == nullptr) {
+		return TriStateBool::UNKNOWN_;
+	}
+
+	cached_ui_render_instance_key key;
+	key.model_num = model_num;
+	key.state_instance_id = gameseq_get_state_instance_id();
+	key.instance_data_hash = instance_data_hash;
+
+	auto& entry = Cached_ui_render_instance_cache[key];
+
+	auto created_new = false;
+
+	if (entry.model_instance < 0) {
+		entry.model_instance = model_create_instance(model_objnum_special::OBJNUM_NONE, model_num);
+		if (entry.model_instance < 0) {
+			Warning(LOCATION, "Failed to create cached UI render model instance for model id %d.", model_num);
+			Cached_ui_render_instance_cache.erase(key);
+			*model_instance_out = -1;
+			return TriStateBool::UNKNOWN_;
+		}
+		created_new = true;
+	}
+
+	entry.last_used_timestamp = ui_timestamp();
+	*model_instance_out = entry.model_instance;
+	return created_new ? TriStateBool::TRUE_ : TriStateBool::FALSE_;
+}
+
+void model_process_cached_ui_render_instances()
+{
+	const auto now = ui_timestamp();
+
+	if (Ui_render_instance_cache_last_processed_timestamp.isValid() &&
+		ui_timestamp_get_delta(Ui_render_instance_cache_last_processed_timestamp, now) == 0) {
+		return;
+	}
+
+	Ui_render_instance_cache_last_processed_timestamp = now;
+
+	for (auto it = Cached_ui_render_instance_cache.begin(); it != Cached_ui_render_instance_cache.end();) {
+		if (it->second.model_instance < 0 || !it->second.last_used_timestamp.isValid() ||
+			ui_timestamp_get_delta(it->second.last_used_timestamp, now) > UI_RENDER_INSTANCE_CACHE_UNUSED_MS_GRACE) {
+			if (it->second.model_instance >= 0) {
+				model_delete_instance(it->second.model_instance);
+			}
+			it = Cached_ui_render_instance_cache.erase(it);
+		} else {
+			++it;
+		}
+	}
+}
+
+void model_clear_cached_ui_render_instances()
+{
+	for (auto& instance : Cached_ui_render_instance_cache) {
+		if (instance.second.model_instance >= 0) {
+			model_delete_instance(instance.second.model_instance);
+		}
+	}
+
+	Cached_ui_render_instance_cache.clear();
+	Ui_render_instance_cache_last_processed_timestamp = UI_TIMESTAMP::invalid();
+}
+
 model_batch_buffer TransformBufferHandler;
 
 model_render_params::model_render_params() :
@@ -3220,9 +3324,9 @@ bool render_tech_model(tech_render_type model_type, int x1, int y1, int x2, int
 
 	int model_instance = -1;
 
-	// Create an instance for ships that can be used to clear out destroyed subobjects from rendering
+	// Get a cached UI render instance for ships so repeated UI/Lua renders avoid per-call allocation churn
 	if (model_type == TECH_SHIP) {
-		model_instance = model_create_instance(model_objnum_special::OBJNUM_NONE, model_num);
+		model_get_cached_ui_render_instance(model_num, &model_instance);
 		model_set_up_techroom_instance(&Ship_info[class_idx], model_instance);
 	}
 
@@ -3252,9 +3356,5 @@ bool render_tech_model(tech_render_type model_type, int x1, int y1, int x2, int
 	g3_end_frame();
 	gr_reset_clip();
 
-	// Now that we've rendered the frame we can remove the instance if one was created for ships
-	if (model_type == TECH_SHIP)
-		model_delete_instance(model_instance);
-
 	return true;
 }

code/model/modelrender.h

@@ -16,6 +16,7 @@
 #include "model/model.h"
 #include "mission/missionparse.h"
 #include "graphics/util/UniformBuffer.h"
+#include "utils/boost/hash_combine.h"
 
 extern SCP_vector<light> Lights;
 extern int Num_lights;
@@ -159,6 +160,35 @@ class model_render_params
 	float get_alpha_mult() const;
 };
 
+struct cached_ui_render_instance_key {
+	int model_num;
+	int state_instance_id;
+	size_t instance_data_hash;
+
+	bool operator==(const cached_ui_render_instance_key& other) const
+	{
+		return model_num == other.model_num && state_instance_id == other.state_instance_id &&
+			   instance_data_hash == other.instance_data_hash;
+	}
+};
+
+struct cached_ui_render_instance_key_hash {
+	size_t operator()(const cached_ui_render_instance_key& key) const
+	{
+		size_t seed = 0;
+
+		boost::hash_combine(seed, key.model_num);
+		boost::hash_combine(seed, key.state_instance_id);
+		boost::hash_combine(seed, key.instance_data_hash);
+		return seed;
+	}
+};
+
+struct cached_ui_render_instance_entry {
+	int model_instance = -1;
+	UI_TIMESTAMP last_used_timestamp = UI_TIMESTAMP::invalid();
+};
+
 struct arc_effect
 {
 	matrix4 transform;
@@ -319,6 +349,11 @@ void model_render_insignias(const insignia_draw_data* insignia);
 void model_render_set_wireframe_color(const color* clr);
 bool render_tech_model(tech_render_type model_type, int x1, int y1, int x2, int y2, float zoom, bool lighting, int class_idx, const matrix* orient, const SCP_string& pof_filename = "", float closeup_zoom = 0, const vec3d* closeup_pos = &vmd_zero_vector, const SCP_string& tcolor = "");
 
+size_t model_hash_subsystem_name_list_for_cache(const SCP_vector<SCP_string>& subsystem_names);
+TriStateBool model_get_cached_ui_render_instance(int model_num, int* model_instance_out, size_t instance_data_hash = 0);
+void model_clear_cached_ui_render_instances();
+void model_process_cached_ui_render_instances();
+
 float convert_distance_and_diameter_to_pixel_size(float distance, float diameter, float field_of_view, int screen_width);
 
 float model_render_get_diameter_clamped_to_min_pixel_size(const vec3d* pos, float diameter, float min_pixel_size);