ReC98/th05/main/bullet/laser.hpp

#define LASER_DISTANCE_MIN to_sp(16.0f)
#define LASER_DISTANCE_MAX to_sp(550.0f) // Far away enough?

static const pixel_t LASER_SHOOTOUT_DECAY_WIDTH = 6;
static const pixel_t LASER_SHOOTOUT_DECAY_WIDTH_MAX = 28;

enum laser_flag_t {
	LF_FREE = 0,
	LF_SHOOTOUT = 1,
	LF_FIXED_WAIT_TO_GROW = 2,
	LF_FIXED_GROW = 3,

	// Fixed laser has reached its target width and will now actually kill the
	// player on contact.
	LF_FIXED_ACTIVE = 4,

	// Fixed laser will shrink to a width of 1 and then either be removed
	// (LF_FIXED_SHRINK) or go back to LF_FIXED_WAIT_TO_GROW with its [age]
	// reset to 0 (LF_FIXED_SHRINK_AND_WAIT_TO_GROW).
	LF_FIXED_SHRINK = 5,
	LF_FIXED_SHRINK_AND_WAIT_TO_GROW = 6,

	// Shootout laser is reduced to the two edges parallel to its moving
	// direction, which are drawn as 1-pixel lines. The laser "grows" until its
	// width reaches LASER_SHOOTOUT_DECAY_WIDTH_MAX, at which it's removed.
	LF_SHOOTOUT_DECAY = 7,

	_laser_flag_t_FORCE_UINT8 = 0xFF
};

struct laser_coords_t {
	PlayfieldPoint origin;

	// Start and end point on the infinite [angle]° line starting at [origin]
	// that make up the actually rendered (and damaging) laser.
	Subpixel starts_at_distance;
	Subpixel ends_at_distance;

	unsigned char angle;

	union {
		// ZUN landmine: LF_FIXED_SHRINK and LF_FIXED_SHRINK_AND_WAIT_TO_GROW
		// are effectively limited to a maximum width of 127 pixels due to an
		// implementation convenience in their update code. For larger values,
		// their shrink animation wouldn't play, and the laser will transition
		// to its next flag immediately.
		pixel_delta_8_t shrink;

		// Other types have no limit besides the 8-bit one inherent to the
		// type. Shootout lasers should probably still be kept below
		// LASER_SHOOTOUT_DECAY_WIDTH_MAX though, as any larger value would
		// skip the decay animation.
		pixel_length_8_t nonshrink;
	} width;
};

struct Laser {
	laser_flag_t flag;
	vc_t col;
	laser_coords_t coords;

	// Truncated to 8 bits by the spawn function! Should have therefore rather
	// been a SubpixelLength8.
	Subpixel shootout_speed;

	int age;
	union {
		// [age] at which a fixed laser should transition from
		// LF_FIXED_WAIT_TO_GROW to LF_FIXED_GROW.
		int grow;
		// [age] at which a shoot-out laser should stop growing and start
		// moving along the infinite [angle]° line.
		int moveout;
	} active_at_age;

	// [age] at which a fixed laser should transition from LF_FIXED_ACTIVE to
	// LF_FIXED_SHRINK.
	int shrink_at_age;

	// [width] (in pixels) at which a fixed laser should transition from
	// LF_FIXED_GROW to LF_FIXED_ACTIVE.
	pixel_length_8_t grow_to_width;

	uint8_t padding[3];

	void fixed_init(const PlayfieldPoint &origin) {
		flag = LF_FIXED_WAIT_TO_GROW;
		coords.origin = origin;
		coords.starts_at_distance.v = LASER_DISTANCE_MIN;
		coords.ends_at_distance.v = LASER_DISTANCE_MAX;
		age = 0;
	}
};

#define LASER_COUNT 32

extern Laser lasers[LASER_COUNT];
extern Laser laser_template;

/// Control
/// -------
/// "Manual" lasers ignore any age fields from the laser template.

#pragma codeseg LASER_SC_TEXT

// Spawns a new shoot-out laser based on the [laser_template].
void near lasers_shootout_add(void);

// Creates a new fixed laser based on the [laser_template] in the given [slot]
// if that one is currently empty.
void pascal near laser_fixed_spawn(int slot);

// Creates a new fixed, manually controlled laser based on the [laser_template]
// in the given [slot] if that one is currently empty.
void pascal near laser_manual_fixed_spawn(int slot);

// Starts the growing phase of the manually controlled fixed laser at [slot].
void pascal near laser_manual_grow(int slot);

// Transitions the laser at [slot] to a stopping phase appropriate for its
// current one.
void pascal near laser_stop(int slot);

#pragma codeseg
/// -------

// Returns `true` if the laser is entirely off-screen.
bool16 pascal near laser_render_ray(const laser_coords_t near& coords);

// Processes any collision between the given [laser] and the player.
void pascal near laser_hittest(Laser near& laser);

#pragma codeseg main__TEXT main_01

void near lasers_update(void);

// Also sets any clipped lasers to LF_FREE.
void near lasers_render(void);

#pragma codeseg