all the consts!

Some experimentation resulted in a lot of const-cascading.  This PR applies `const` to a large number of functions.

code/ai/ai.h

@@ -534,7 +534,7 @@ extern void ai_dock_with_object(object *docker, int docker_index, object *dockee
 extern void ai_stay_still(object *still_objp, vec3d *view_pos);
 extern void ai_do_default_behavior(object *obj);
 extern void ai_start_waypoints(object *objp, waypoint_list *wp_list, int wp_flags, int start_index);
-extern void ai_ship_hit(object *objp_ship, object *hit_objp, vec3d *hit_normal);
+extern void ai_ship_hit(object *objp_ship, object *hit_objp, const vec3d *hit_normal);
 extern void ai_ship_destroy(int shipnum);
 extern vec3d ai_get_acc_limit(vec3d* vel_limit, const object* objp);
 extern void ai_turn_towards_vector(const vec3d *dest, object *objp, const vec3d *slide_vec, const vec3d *rel_pos, float bank_override, int flags, const vec3d *rvec = nullptr, const vec3d* turnrate_mod = nullptr);

code/ai/aibig.cpp

@@ -67,8 +67,8 @@ int	ai_big_maybe_follow_subsys_path(int do_dot_check=1);
 void ai_big_strafe_position();
 static int ai_big_strafe_maybe_retreat(const vec3d *target_pos);
 
-extern void compute_desired_rvec(vec3d *rvec, vec3d *goal_pos, vec3d *cur_pos);
-extern void big_ship_collide_recover_start(object *objp, object *big_objp, vec3d *collision_normal);
+extern void compute_desired_rvec(vec3d *rvec, const vec3d *goal_pos, const vec3d *cur_pos);
+extern void big_ship_collide_recover_start(const object *objp, const object *big_objp, const vec3d *collision_normal);
 
 
 //	Called by ai_big_pick_attack_point.

code/ai/aicode.cpp

@@ -1197,7 +1197,7 @@ int ai_is_stealth_visible(const object *viewer_objp, const object *stealth_objp)
  * Forward vector is the forward vector of the ship.
  * If from_dot == NULL, don't fill it in.
  */
-float compute_dots(object *objp, object *other_objp, float *to_dot, float *from_dot)
+float compute_dots(const object *objp, const object *other_objp, float *to_dot, float *from_dot)
 {
 	vec3d	v2o;
 	float		dist;
@@ -7240,7 +7240,7 @@ static void ai_chase_eb(ai_info *aip, vec3d *predicted_enemy_pos)
 //	Assumes ship_objp is not moving.
 //	Returns negative time if not going to hit.
 //	This is a very approximate function, but is pretty fast.
-float ai_endangered_time(object *ship_objp, object *weapon_objp)
+float ai_endangered_time(const object *ship_objp, const object *weapon_objp)
 {
 	float		to_dot, from_dot, dist;
 
@@ -7693,7 +7693,7 @@ int maybe_avoid_big_ship(object *objp, object *ignore_objp, ai_info *aip, vec3d
  * Set desired right vector for ships flying towards another ship.
  * Since this is governed only by vector to target, it causes ships to align bank and look less chaotic.
  */
-void compute_desired_rvec(vec3d *rvec, vec3d *goal_pos, vec3d *cur_pos)
+void compute_desired_rvec(vec3d *rvec, const vec3d *goal_pos, const vec3d *cur_pos)
 {
 	vec3d	v2e;
 
@@ -15918,7 +15918,7 @@ int firing_aspect_seeking_bomb(object *objp)
 // *objp collided with big ship *big_objp at some global point.
 // Make it fly away from the collision point.
 // collision_normal is NULL, when a collision is imminent and we just want to bug out.
-void big_ship_collide_recover_start(object *objp, object *big_objp, vec3d *collision_normal)
+void big_ship_collide_recover_start(const object *objp, const object *big_objp, const vec3d *collision_normal)
 {
 	ai_info	*aip;
 
@@ -15955,7 +15955,7 @@ void big_ship_collide_recover_start(object *objp, object *big_objp, vec3d *colli
 
 float max_lethality = 0.0f;
 
-void ai_update_lethality(object *pship_obj, object *other_obj, float damage)
+void ai_update_lethality(const object *pship_obj, const object *other_obj, float damage)
 {
 	// Goober5000 - stop any trickle-down errors from ship_do_damage
 	Assert(other_obj);
@@ -16008,7 +16008,7 @@ void ai_update_lethality(object *pship_obj, object *other_obj, float damage)
 /**
  * Object *objp_ship was hit by either weapon *objp_weapon or collided into by ship hit_objp
  */
-void ai_ship_hit(object *objp_ship, object *hit_objp, vec3d *hit_normal)
+void ai_ship_hit(object *objp_ship, object *hit_objp, const vec3d *hit_normal)
 {
 	int		hitter_objnum = -2;
 	object	*objp_hitter = nullptr;

code/debris/debris.cpp

@@ -376,7 +376,7 @@ MONITOR(NumHullDebris)
  * @param exp_force		Explosion force, used to assign velocity to pieces. 1.0f assigns velocity like before. 2.0f assigns twice as much to non-inherited part of velocity
  * @param source_subsys	The subsystem this debris came from, if any
  */
-object *debris_create(object *source_obj, int model_num, int submodel_num, vec3d *pos, vec3d *exp_center, bool hull_flag, float exp_force, ship_subsys* source_subsys)
+object *debris_create(object *source_obj, int model_num, int submodel_num, const vec3d *pos, const vec3d *exp_center, bool hull_flag, float exp_force, const ship_subsys* source_subsys)
 {
 	int             parent_objnum;
 	object  *obj;
@@ -401,7 +401,7 @@ object *debris_create(object *source_obj, int model_num, int submodel_num, vec3d
 	return obj;
 }
 
-object *debris_create_only(int parent_objnum, int parent_ship_class, int alt_type_index, int team, float hull_strength, int spark_timeout, int model_num, int submodel_num, vec3d *pos, matrix *orient, bool hull_flag, bool vaporize, int damage_type_idx)
+object *debris_create_only(int parent_objnum, int parent_ship_class, int alt_type_index, int team, float hull_strength, int spark_timeout, int model_num, int submodel_num, const vec3d *pos, const matrix *orient, bool hull_flag, bool vaporize, int damage_type_idx)
 {
 	int		objnum;
 	object	*obj;
@@ -666,7 +666,7 @@ object *debris_create_only(int parent_objnum, int parent_ship_class, int alt_typ
 	return obj;
 }
 
-void debris_create_set_velocity(debris *db, ship *source_shipp, vec3d *exp_center, float exp_force, ship_subsys* source_subsys)
+void debris_create_set_velocity(const debris *db, const ship *source_shipp, const vec3d *exp_center, float exp_force, const ship_subsys* source_subsys)
 {
 	auto obj = &Objects[db->objnum];
 	auto source_obj = (source_shipp == nullptr) ? nullptr : &Objects[source_shipp->objnum];
@@ -1105,7 +1105,7 @@ int debris_check_collision(object *pdebris, object *other_obj, vec3d *hitpos, co
 /**
  * Return the team field for a debris object
  */
-int debris_get_team(object *objp)
+int debris_get_team(const object *objp)
 {
 	Assert( objp->type == OBJ_DEBRIS );
 	Assert( objp->instance >= 0 && objp->instance < (int)Debris.size() );
@@ -1207,17 +1207,18 @@ void debris_render(object * obj, model_draw_list *scene)
 	}
 }
 
-bool debris_is_generic(debris *db)
+bool debris_is_generic(const debris *db)
 {
 	return db->model_num == Debris_model;
 }
 
-bool debris_is_vaporized(debris *db)
+bool debris_is_vaporized(const debris *db)
 {
 	return db->model_num == Debris_vaporize_model;
 }
 
-void create_generic_debris(object* ship_objp, vec3d* pos, float min_num_debris, float max_num_debris, float speed_mult, bool use_ship_debris) {
+void create_generic_debris(object* ship_objp, const vec3d* pos, float min_num_debris, float max_num_debris, float speed_mult, bool use_ship_debris)
+{
 	Assertion(ship_objp->type == OBJ_SHIP, "create_generic_debris called for a non-ship, only ships can spew debris!");
 	if (ship_objp->type != OBJ_SHIP)
 		return;

code/debris/debris.h

@@ -71,29 +71,29 @@ void debris_delete( object * obj );
 void debris_process_post( object * obj, float frame_time);
 
 // Create debris, set velocity, and fire scripting hook
-object *debris_create( object *source_obj, int model_num, int submodel_num, vec3d *pos, vec3d *exp_center, bool hull_flag, float exp_force, ship_subsys* source_subsys = nullptr );
+object *debris_create(object *source_obj, int model_num, int submodel_num, const vec3d *pos, const vec3d *exp_center, bool hull_flag, float exp_force, const ship_subsys* source_subsys = nullptr);
 
 // Create debris but don't do anything else
-object *debris_create_only(int parent_objnum, int parent_ship_class, int alt_type_index, int team, float hull_strength, int spark_timeout, int model_num, int submodel_num, vec3d *pos, matrix *orient, bool hull_flag, bool vaporize, int damage_type_idx);
+object *debris_create_only(int parent_objnum, int parent_ship_class, int alt_type_index, int team, float hull_strength, int spark_timeout, int model_num, int submodel_num, const vec3d *pos, const matrix *orient, bool hull_flag, bool vaporize, int damage_type_idx);
 
 // Set velocity after debris creation
-void debris_create_set_velocity(debris *db, ship *source_shipp, vec3d *exp_center, float exp_force, ship_subsys* source_subsys = nullptr);
+void debris_create_set_velocity(const debris *db, const ship *source_shipp, const vec3d *exp_center, float exp_force, const ship_subsys* source_subsys = nullptr);
 
 // Fire scripting hook after debris creation
 void debris_create_fire_hook(object *obj, object *source_obj);
 
 int debris_check_collision( object * obj, object * other_obj, vec3d * hitpos, collision_info_struct *debris_hit_info=NULL, vec3d* hitnormal = NULL );
 void debris_hit( object * debris_obj, object * other_obj, vec3d * hitpos, float damage, vec3d* force );
-int debris_get_team(object *objp);
 
 void debris_add_to_hull_list(debris *db);
 void debris_remove_from_hull_list(debris *db);
 
-bool debris_is_generic(debris *db);
-bool debris_is_vaporized(debris *db);
+int debris_get_team(const object *objp);
+bool debris_is_generic(const debris *db);
+bool debris_is_vaporized(const debris *db);
 
 // creates a burst of generic debris at hitpos from ship_objp, with a random number between min and max
 // use_ship_debris is for whether the ship's generic debris should be used, or simply debris01.pof
-void create_generic_debris(object* ship_objp, vec3d* hitpos, float min_num_debris, float max_num_debris, float speed_mult, bool use_ship_debris);
+void create_generic_debris(object* ship_objp, const vec3d* hitpos, float min_num_debris, float max_num_debris, float speed_mult, bool use_ship_debris);
 
 #endif // _DEBRIS_H

code/decals/decals.cpp

@@ -501,7 +501,7 @@ void renderAll() {
 	draw_list.render();
 }
 
-void addDecal(creation_info& info, object* host, int submodel, const vec3d& local_pos, const matrix& local_orient) {
+void addDecal(creation_info& info, const object* host, int submodel, const vec3d& local_pos, const matrix& local_orient) {
 	if (!Decal_system_active || !Decal_option_active) {
 		return;
 	}

code/decals/decals.h

@@ -134,7 +134,7 @@ void renderAll();
  * orientation should look along the direction
  */
 void addDecal(creation_info& info,
-			  object* host,
+			  const object* host,
 			  int submodel,
 			  const vec3d& local_pos,
 			  const matrix& local_orient);

code/hud/hud.h

@@ -57,7 +57,7 @@ typedef struct hud_subsys_damage
 {
 	int	str;
 	int	type;
-	char* name;
+	const char* name;
 } hud_subsys_damage;
 
 // used for hudtarget

code/hud/hudartillery.cpp

@@ -261,7 +261,7 @@ void ssm_init()
 	validate_SSM_entries();
 }
 
-void ssm_get_random_start_pos(vec3d *out, vec3d *start, matrix *orient, size_t ssm_index)
+void ssm_get_random_start_pos(vec3d *out, const vec3d *start, const matrix *orient, size_t ssm_index)
 {
 	vec3d temp;
 	ssm_info *s = &Ssm_info[ssm_index];
@@ -305,7 +305,8 @@ void ssm_level_init()
 }
 
 // start a subspace missile effect
-void ssm_create(object *target, vec3d *start, size_t ssm_index, ssm_firing_info *override, int team)
+// (it might be possible to make `target` const, but that would set off another const-cascade)
+void ssm_create(object *target, const vec3d *start, size_t ssm_index, const ssm_firing_info *override, int team)
 {	
 	ssm_strike ssm;
 	matrix dir;

code/hud/hudartillery.h

@@ -90,7 +90,8 @@ void hud_artillery_update();
 void hud_artillery_render();
 
 // start a subspace missile effect
-void ssm_create(object *target, vec3d *start, size_t ssm_index, ssm_firing_info *override, int team);
+// (it might be possible to make `target` const, but that would set off another const-cascade)
+void ssm_create(object *target, const vec3d *start, size_t ssm_index, const ssm_firing_info *override, int team);
 
 // Goober5000
 extern int ssm_info_lookup(const char *name);

code/hud/hudescort.cpp

@@ -75,7 +75,7 @@ HudGauge(HUD_OBJECT_ESCORT, HUD_ESCORT_VIEW, false, false, (VM_EXTERNAL | VM_DEA
 {
 }
 
-void HudGaugeEscort::initHeaderText(char *text)
+void HudGaugeEscort::initHeaderText(const char *text)
 {
 	strcpy_s(header_text, text);
 }
@@ -135,7 +135,7 @@ void HudGaugeEscort::initRightAlignNames(bool align)
 	right_align_names = align;
 }
 
-void HudGaugeEscort::initBitmaps(char *fname_top, char *fname_middle, char *fname_bottom)
+void HudGaugeEscort::initBitmaps(const char *fname_top, const char *fname_middle, const char *fname_bottom)
 {
 	Escort_gauges[0].first_frame = bm_load_animation(fname_top, &Escort_gauges[0].num_frames);
 	if (Escort_gauges[0].first_frame == -1) {
@@ -885,7 +885,7 @@ void hud_remove_ship_from_escort(int objnum)
  * @param objp      The object hit
  * @param quadrant  Shield quadrant on the object that was hit, alternatively -1 if no shield
  */
-void hud_escort_ship_hit(object *objp, int  /*quadrant*/)
+void hud_escort_ship_hit(const object *objp, int  /*quadrant*/)
 {
 	// no ships on the escort list in multiplayer dogfight
 	if(MULTI_DOGFIGHT){

code/hud/hudescort.h

@@ -27,7 +27,7 @@ void	hud_setup_escort_list(int level = 1);
 void	hud_resort_escort_list();
 void	hud_add_remove_ship_escort(int objnum, int supress_feedback = 0);
 void	hud_escort_clear_all(bool clear_flags = false);
-void	hud_escort_ship_hit(object *objp, int quadrant);
+void	hud_escort_ship_hit(const object *objp, int quadrant);
 void	hud_escort_target_next();
 void	hud_escort_cull_list();
 void	hud_add_ship_to_escort(int objnum, int supress_feedback);
@@ -55,8 +55,8 @@ class HudGaugeEscort: public HudGauge
 	bool right_align_names;				// whether or not to right-align ship names
 public:
 	HudGaugeEscort();
-	void initBitmaps(char *fname_top, char *fname_middle, char *fname_bottom);
-	void initHeaderText(char *text);
+	void initBitmaps(const char *fname_top, const char *fname_middle, const char *fname_bottom);
+	void initHeaderText(const char *text);
 	void initHeaderTextOffsets(int x, int y);
 	void initListStartOffsets(int x, int y);
 	void initEntryHeight(int h);

code/hud/hudshield.cpp

@@ -178,7 +178,7 @@ bool shield_ani_warning_displayed_already = false;
 
 // called at beginning of level to page in all ship icons
 // used in this level
-void hud_ship_icon_page_in(ship_info *sip)
+void hud_ship_icon_page_in(const ship_info *sip)
 {
 	hud_frames	*sgp;
 
@@ -287,7 +287,7 @@ void hud_augment_shield_quadrant(object *objp, int direction)
 // Try to find a match between filename and the names inside
 // of Hud_shield_filenames.  This will provide us with an 
 // association of ship class to shield icon information.
-void hud_shield_assign_info(ship_info *sip, char *filename)
+void hud_shield_assign_info(ship_info *sip, const char *filename)
 {
 	ubyte i;
 
@@ -300,10 +300,10 @@ void hud_shield_assign_info(ship_info *sip, char *filename)
 
 	//No HUD icon found. Add one!
 	sip->shield_icon_index = (unsigned char) Hud_shield_filenames.size();
-	Hud_shield_filenames.push_back((SCP_string)filename);
+	Hud_shield_filenames.emplace_back(filename);
 }
 
-void hud_show_mini_ship_integrity(object *objp, int x_force, int y_force)
+void hud_show_mini_ship_integrity(const object *objp, int x_force, int y_force)
 {
 	char	text_integrity[64];
 	int	numeric_integrity;
@@ -350,7 +350,7 @@ void hud_show_mini_ship_integrity(object *objp, int x_force, int y_force)
 
 // Draw the miniature shield icon that is drawn near the reticle
 // this function is only used by multi_ingame_join_display_ship() in multi_ingame.cpp as of the new HudGauge implementation (Swifty)
-void hud_shield_show_mini(object *objp, int x_force, int y_force, int x_hull_offset, int y_hull_offset)
+void hud_shield_show_mini(const object *objp, int x_force, int y_force, int x_hull_offset, int y_hull_offset)
 {
 	float			max_shield;
 	int			hud_color_index, range, frame_offset;
@@ -426,7 +426,7 @@ void hud_shield_show_mini(object *objp, int x_force, int y_force, int x_hull_off
 // reset the shield_hit_info data structure
 // pass NULL as objp if you only need to initialize a shield_hit_info without an
 // associated ship
-void shield_info_reset(object *objp, shield_hit_info *shi)
+void shield_info_reset(const object *objp, shield_hit_info *shi)
 {
 	int n_quadrants = (objp != NULL) ? objp->n_quadrants : 0;
 
@@ -451,7 +451,7 @@ void shield_info_reset(object *objp, shield_hit_info *shi)
 // input:	player	=>	optional parameter (default value 0).  This is to indicate that player shield hit
 //								info should be reset.  This is normally not the case.
 //								is for the player's current target
-void hud_shield_hit_reset(object *objp, int player)
+void hud_shield_hit_reset(const object *objp, int player)
 {
 	shield_hit_info	*shi;
 
@@ -495,7 +495,7 @@ void hud_shield_hit_update()
 // input:
 //				objp		=>	object pointer for ship that has been hit
 //				quadrant	=> quadrant of shield getting hit (-1 if no shield is present)
-void hud_shield_quadrant_hit(object *objp, int quadrant)
+void hud_shield_quadrant_hit(const object *objp, int quadrant)
 {
 	shield_hit_info	*shi;
 	int					num;
@@ -550,7 +550,7 @@ void HudGaugeShield::render(float  /*frametime*/)
 {
 }
 
-void HudGaugeShield::showShields(object *objp, int mode)
+void HudGaugeShield::showShields(const object *objp, int mode)
 {
 //	static int fod_model = -1;
 	float			max_shield;
@@ -924,7 +924,7 @@ void HudGaugeShieldMini::init2DigitOffsets(int x, int y)
 	Mini_2digit_offsets[1] = y;
 }
 
-void HudGaugeShieldMini::initBitmaps(char *fname)
+void HudGaugeShieldMini::initBitmaps(const char *fname)
 {
 	Shield_mini_gauge.first_frame = bm_load_animation(fname, &Shield_mini_gauge.num_frames);
 	if ( Shield_mini_gauge.first_frame == -1 ) {
@@ -953,7 +953,7 @@ void HudGaugeShieldMini::pageIn()
 }
 
 // Draw the miniature shield icon that is drawn near the reticle
-void HudGaugeShieldMini::showMiniShields(object *objp)
+void HudGaugeShieldMini::showMiniShields(const object *objp)
 {
 	if (Shield_mini_gauge.first_frame < 0)
 		return;