Disable uneccesary raycast (#6811)

Author: BMagnu

code/ai/aibig.cpp

@@ -146,6 +146,10 @@ void ai_bpap(const object *objp, const vec3d *attacker_objp_pos, const vec3d *at
 
 	*attack_point = best_point;
 
+	//The following raycast tends to make up 10%(!) of total AI-frametime for basically no benefit, especially in the common case for turrets where the normal isn't even queried.
+	if (surface_normal == nullptr && Disable_expensive_turret_target_check)
+		return;
+
 	// Cast from attack_objp_pos to local_attack_pos and check for nearest collision.
 	// If no collision, cast to (0,0,0) [center of big ship]**  [best_point initialized to 000]
 

code/mod_table/mod_table.cpp

@@ -171,6 +171,7 @@ EscapeKeyBehaviorInOptions escape_key_behavior_in_options;
 bool Fix_asteroid_bounding_box_check;
 bool Disable_intro_movie;
 bool Show_locked_status_scramble_missions;
+bool Disable_expensive_turret_target_check;
 
 
 #ifdef WITH_DISCORD
@@ -1534,6 +1535,10 @@ void parse_mod_table(const char *filename)
 				stuff_boolean(&Show_locked_status_scramble_missions);
 			}
 
+			if (optional_string("$Disable expensive turret target check:")) {
+				stuff_boolean(&Disable_expensive_turret_target_check);
+			}
+
 			// end of options ----------------------------------------
 
 			// if we've been through once already and are at the same place, force a move
@@ -1769,6 +1774,7 @@ void mod_table_reset()
 	Fix_asteroid_bounding_box_check = false;
 	Disable_intro_movie = false;
 	Show_locked_status_scramble_missions = false;
+	Disable_expensive_turret_target_check = false;
 }
 
 void mod_table_set_version_flags()
@@ -1794,5 +1800,6 @@ void mod_table_set_version_flags()
 		Use_model_eyepoint_for_set_camera_host = true;
 		Use_model_eyepoint_normals = true;
 		Fix_asteroid_bounding_box_check = true;
+		Disable_expensive_turret_target_check = true;
 	}
 }

code/mod_table/mod_table.h

@@ -186,6 +186,7 @@ extern EscapeKeyBehaviorInOptions escape_key_behavior_in_options;
 extern bool Fix_asteroid_bounding_box_check;
 extern bool Disable_intro_movie;
 extern bool Show_locked_status_scramble_missions;
+extern bool Disable_expensive_turret_target_check;
 
 void mod_table_init();
 void mod_table_post_process();