effects.h File Reference

Jo Engine Function prototypes special effects (Laser beam, fire, smoke, flash, shake, etc). More...

Go to the source code of this file.

Data Structures
struct	jo_homing_laser
	Homing laser effect definition. More...
struct	jo_effect_def
	Definition of an effect (shared by the effects of the same kind). More...

Macros
#define	JO_EFFECT_MAX
	Effects at the same time (the oldest one is reused).
#define	JO_EFFECT_MAX_FRAMES
	Frames of the animation of an effect at most.
#define	JO_EFFECT_HALF_TRANSPARENT
	The sprite is mixed with what is behind (VDP1 half transparency: costly, for small sprites only).
#define	JO_EFFECT_STANDING
	The sprite stands on its position (else it is centered on it).
#define	JO_EFFECT_RANDOM_FLIP
	The sprite is flipped at random (the effects don't look the same).

Functions
void	jo_init_homing_laser (jo_homing_laser *const homing_laser, const int sprite_id, const unsigned short thickness, const int z, const unsigned short nb_sections)
	Init jo_homing_laser struct.
void	jo_draw_homing_laser (jo_homing_laser *const homing_laser)
	Draw homing laser effect.
void	jo_effect_add (const jo_effect_def *const def, const jo_pos3D_fixed *const position, const int delay)
	Add an effect.
void	jo_effects_clear (void)
	Remove all the effects, the flash and the shake.
void	jo_effects_update (void)
	Animate the effects, the flash and the shake: once per frame of the game.
int	jo_effects_draw (void)
	Draw the effects (in the world: the camera matrix is the current matrix, see jo_3d_set_depth_bias()).
void	jo_effect_flash (const int r, const int g, const int b, const int frames)
	Flash of the screen: the color offset of the VDP2 is added to all the screens, it fades to 0.
void	jo_effect_fade (const int darkness, const int frames)
	Fade of the screen to black (or back): the color offset of the VDP2 (see jo_effect_flash()).
bool	jo_effect_is_fading (void)
	Check if the fade is not finished (see jo_effect_fade()).
void	jo_effect_shake (const int amount, const int frames)
	Shake of the camera.
void	jo_effect_get_shake (jo_pos3D_fixed *const offset)
	Offset of the camera of the shake (add it to the position of the eyes).

Detailed Description

Jo Engine Function prototypes special effects (Laser beam, fire, smoke, flash, shake, etc).

Author

Johannes Fetz

Bug

No known bugs.

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Data Structure Documentation

jo_homing_laser

struct jo_homing_laser

Homing laser effect definition.

Data Fields
bool	center_sprites_according_to_thickness
jo_fixed	horizontal_thickness
jo_vector_fixed	intermediate_point_a
jo_vector_fixed	intermediate_point_b
jo_fixed	length
jo_fixed	section_step
jo_vector_fixed	source
int	sprite_id
jo_vector_fixed	target
bool	use_intermediate_point_a
bool	use_intermediate_point_b
jo_fixed	vertical_thickness

jo_effect_def

struct jo_effect_def

Definition of an effect (shared by the effects of the same kind).

Data Fields
unsigned char	__pad
short	__pad2
unsigned char	flags
unsigned char	frame_count
unsigned char	life
short	rise
short	size_end
short	size_start
short	sprites[(4)]

Macro Definition Documentation

JO_EFFECT_HALF_TRANSPARENT

#define JO_EFFECT_HALF_TRANSPARENT

The sprite is mixed with what is behind (VDP1 half transparency: costly, for small sprites only).

JO_EFFECT_MAX

#define JO_EFFECT_MAX

Effects at the same time (the oldest one is reused).

JO_EFFECT_MAX_FRAMES

#define JO_EFFECT_MAX_FRAMES

Frames of the animation of an effect at most.

JO_EFFECT_RANDOM_FLIP

#define JO_EFFECT_RANDOM_FLIP

The sprite is flipped at random (the effects don't look the same).

JO_EFFECT_STANDING

#define JO_EFFECT_STANDING

The sprite stands on its position (else it is centered on it).

Function Documentation

jo_draw_homing_laser()

void jo_draw_homing_laser

(

jo_homing_laser *const

homing_laser

)

Draw homing laser effect.

Parameters

homing_laser

Homing laser definition

Remarks

source, intermediate_point_a, intermediate_point_b, target and length must be set before this call

jo_effect_add()

void jo_effect_add	(	const jo_effect_def *const	def,
		const jo_pos3D_fixed *const	position,
		const int	delay )

Add an effect.

Parameters

def	Definition (it must stay in memory)
position	Center (or foot: JO_EFFECT_STANDING), world space
delay	Frames before the effect starts (an explosion is a group of fireballs that start one after the other)

jo_effect_fade()

void jo_effect_fade	(	const int	darkness,
		const int	frames )

Fade of the screen to black (or back): the color offset of the VDP2 (see jo_effect_flash()).

Parameters

darkness	0 (no fade) to 255 (black)
frames	Frames of the game to reach it (see jo_effects_update()), 0: now

Remarks

A change of level: fade to black, load, fade back. jo_effects_clear() doesn't change the fade

jo_effect_flash()

void jo_effect_flash	(	const int	r,
		const int	g,
		const int	b,
		const int	frames )

Flash of the screen: the color offset of the VDP2 is added to all the screens, it fades to 0.

Parameters

r	Red (0 to 255: added to the colors)
g	Green
b	Blue
frames	Frames of the game until it is gone

Remarks

The registers are written during the VBLANK (no line of the screen with half of the flash). A brighter flash than the current one replaces it

jo_effect_get_shake()

void jo_effect_get_shake

(

jo_pos3D_fixed *const

offset

)

Offset of the camera of the shake (add it to the position of the eyes).

Parameters

offset

Offset (output, world units Q16.16), 0 when nothing shakes

jo_effect_is_fading()

bool jo_effect_is_fading

(

void

)

Check if the fade is not finished (see jo_effect_fade()).

jo_effect_shake()

void jo_effect_shake	(	const int	amount,
		const int	frames )

Shake of the camera.

Parameters

amount	Amplitude (world units). A stronger shake than the current one replaces it
frames	Frames of the game until it is gone

jo_effects_clear()

void jo_effects_clear

(

void

)

Remove all the effects, the flash and the shake.

jo_effects_draw()

int jo_effects_draw

(

void

)

Draw the effects (in the world: the camera matrix is the current matrix, see jo_3d_set_depth_bias()).

Returns

Number of VDP1 commands (sprites) drawn

jo_effects_update()

void jo_effects_update

(

void

)

Animate the effects, the flash and the shake: once per frame of the game.

jo_init_homing_laser()

void jo_init_homing_laser	(	jo_homing_laser *const	homing_laser,
		const int	sprite_id,
		const unsigned short	thickness,
		const int	z,
		const unsigned short	nb_sections )

Init jo_homing_laser struct.

Parameters

homing_laser	Homing laser definition
sprite_id	Sprite ID
thickness	Horizontal Laser thickness (1 to 256)
z	Default z index (500 for example)
nb_sections	Number of section in the curve aka smoothness (4 to 64 and must be a multiple of 2).

Remarks

nb_sections=20 Should be enough for most case