Add Power-Up Aura

- Spawns on player when they use their first power-up
- Lasts as long as player has any power-up
- A hexagon of animated, additive, fullbright papersprites
  surround and move with the player, takes player's angle

src/k_objects.h

@@ -161,6 +161,10 @@ void Obj_SuperFlickyPlayerCollide(mobj_t *flicky, mobj_t *player);
 void Obj_SuperFlickyLanding(mobj_t *flicky);
 boolean Obj_IsSuperFlickyWhippable(const mobj_t *flicky);
 
+/* Power-Up Aura */
+void Obj_SpawnPowerUpAura(player_t* player);
+void Obj_PowerUpAuraThink(mobj_t* mobj);
+
 #ifdef __cplusplus
 } // extern "C"
 #endif

src/k_powerup.cpp

@@ -25,8 +25,26 @@ tic_t K_PowerUpRemaining(const player_t* player, kartitems_t powerup)
 	}
 }
 
+boolean K_AnyPowerUpRemaining(const player_t* player)
+{
+	for (int k = FIRSTPOWERUP; k < ENDOFPOWERUPS; ++k)
+	{
+		if (K_PowerUpRemaining(player, static_cast<kartitems_t>(k)))
+		{
+			return true;
+		}
+	}
+
+	return false;
+}
+
 void K_GivePowerUp(player_t* player, kartitems_t powerup, tic_t time)
 {
+	if (!K_AnyPowerUpRemaining(player))
+	{
+		Obj_SpawnPowerUpAura(player);
+	}
+
 	switch (powerup)
 	{
 	case POWERUP_SMONITOR:

src/k_powerup.h

@@ -9,6 +9,7 @@ extern "C" {
 #endif
 
 tic_t K_PowerUpRemaining(const player_t *player, kartitems_t powerup);
+boolean K_AnyPowerUpRemaining(const player_t *player);
 void K_GivePowerUp(player_t *player, kartitems_t powerup, tic_t timer);
 void K_DropPowerUps(player_t *player);
 

src/objects/CMakeLists.txt

@@ -22,4 +22,5 @@ target_sources(SRB2SDL2 PRIVATE
 	gachabom-rebound.cpp
 	servant-hand.c
 	super-flicky.cpp
+	powerup-aura.cpp
 )

src/objects/powerup-aura.cpp

@@ -0,0 +1,121 @@
+#include "../info.h"
+#include "../g_game.h"
+#include "../m_fixed.h"
+#include "../k_objects.h"
+#include "../k_powerup.h"
+#include "../p_local.h"
+#include "../p_mobj.h"
+#include "../tables.h"
+
+// copied from objects/monitor.c
+#define FINE90 (FINEANGLES/4)
+#define FINE180 (FINEANGLES/2)
+#define TRUETAN(n) FINETANGENT(FINE90 + (n)) // bruh
+
+#define part_theta(o) ((o)->movedir)
+#define part_seek(o) ((o)->extravalue1)
+
+namespace
+{
+
+constexpr int kSpriteWidth = 32;
+constexpr int kNumSides = 6;
+
+struct Aura : mobj_t
+{
+	angle_t theta() const { return part_theta(this); }
+	void theta(angle_t n) { part_theta(this) = n; }
+
+	unsigned seek() const { return part_seek(this); }
+	void seek(unsigned n) { part_seek(this) = n; }
+
+	mobj_t* origin() const { return players[seek()].mo; }
+
+	static void spawn(int player)
+	{
+		const fixed_t angle_factor = ANGLE_MAX / kNumSides;
+
+		angle_t ang = 0u;
+
+		for (int i = 0; i < kNumSides; ++i)
+		{
+			Aura* x = static_cast<Aura*>(P_SpawnMobj(0, 0, 0, MT_POWERUP_AURA));
+
+			x->theta(ang);
+			x->seek(player);
+
+			ang += angle_factor;
+		}
+	}
+
+	// copied from objects/monitor.c
+	static fixed_t get_inradius(fixed_t length)
+	{
+		return FixedDiv(length, 2 * TRUETAN(FINE180 / kNumSides));
+	}
+
+	bool valid() const
+	{
+		if (seek() >= MAXPLAYERS)
+		{
+			return false;
+		}
+
+		if (!playeringame[seek()])
+		{
+			return false;
+		}
+
+		if (!K_AnyPowerUpRemaining(&players[seek()]))
+		{
+			return false;
+		}
+
+		return true;
+	}
+
+	void move()
+	{
+		if (P_MobjWasRemoved(origin()))
+		{
+			return;
+		}
+
+		P_MoveOrigin(this, origin()->x, origin()->y, origin()->z);
+		P_InstaScale(this, 11 * origin()->scale / 10);
+
+		translate();
+	}
+
+	void translate()
+	{
+		const fixed_t width = scale * kSpriteWidth;
+		const fixed_t rad = get_inradius(width);
+		const angle_t ang = theta() + origin()->angle;
+
+		angle = (ang - ANGLE_90);
+
+		sprxoff = FixedMul(FCOS(ang), rad);
+		spryoff = FixedMul(FSIN(ang), rad);
+	}
+};
+
+}; // namespace
+
+void Obj_SpawnPowerUpAura(player_t* player)
+{
+	Aura::spawn(player - players);
+}
+
+void Obj_PowerUpAuraThink(mobj_t* mobj)
+{
+	Aura* x = static_cast<Aura*>(mobj);
+
+	if (!x->valid())
+	{
+		P_RemoveMobj(x);
+		return;
+	}
+
+	x->move();
+}

src/p_mobj.c

@@ -6698,6 +6698,14 @@ static void P_MobjSceneryThink(mobj_t *mobj)
 	case MT_SUPER_FLICKY_CONTROLLER:
 		Obj_SuperFlickyControllerThink(mobj);
 
+		if (P_MobjWasRemoved(mobj))
+		{
+			return;
+		}
+		break;
+	case MT_POWERUP_AURA:
+		Obj_PowerUpAuraThink(mobj);
+
 		if (P_MobjWasRemoved(mobj))
 		{
 			return;