glow.h File Reference

Jo Engine glows: the halo of light around a lamp (a soft disc of its color, without edge, and a few thin rays of light, added to the image). More...

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Macros
#define	JO_3D_GLOW_MAX
	Max glows (lamps).

Functions
int	jo_3d_glow_add (const jo_pos3D_fixed *const position, const unsigned char r, const unsigned char g, const unsigned char b, const int radius, const int intensity)
	Add a glow.
void	jo_3d_glow_set_intensity (const int id, const int intensity)
	Change the intensity of a glow (a lamp that flickers, an alarm).
void	jo_3d_glow_set_position (const int id, const jo_pos3D_fixed *const position)
	Move a glow.
void	jo_3d_glow_set_color (const int id, const unsigned char r, const unsigned char g, const unsigned char b)
	Change the color of a glow.
void	jo_3d_glows_clear (void)
	Remove all the glows.
void	jo_3d_glows_set_rays (const int light, const int diagonal_light)
	The light of the rays of the glows (the star around the disc), before jo_3d_glows_enable() (its characters are built then).
bool	jo_3d_glows_enable (const bool enabled)
	Turn the glows on or off: the VDP2 layers (see the remarks of this file: the 3D planes are hidden while they are on).
void	jo_3d_glows_set_occlusion (bool(*hit)(const jo_pos3D_fixed *const origin, const jo_pos3D_fixed *const dir, const jo_fixed max_t))
	The walls hide the glows behind them (a ray from the camera to the lamp, a few each frame).
void	jo_3d_glows_set_clip (bool(*clip)(const jo_pos3D_fixed *const position, jo_3d_rect *const rect))
	The glows are seen only in a rectangle of the screen: the rectangle where the place of the lamp is seen (a lamp in a room seen through a door: its glow stays in the door, see jo_cells_view_rect_at()). A window of the VDP2 cuts the disc to the rectangle.
void	jo_3d_glows_draw (const jo_pos3D_fixed *const camera)
	Place the glows seen from the camera (once per frame, after the camera: its matrix is the current matrix).

Detailed Description

Jo Engine glows: the halo of light around a lamp (a soft disc of its color, without edge, and a few thin rays of light, added to the image).

Author

Johannes Fetz

• The VDP1 blends at 50 % only: a half transparent sprite shows its edge (and darkens the dark walls around it). The glows are drawn by the VDP2 instead: NBG2 and NBG3 over the sprite layer, with the color calculation "add": the color of a glow is added to the 3D view (0 at its edge: no edge, like the light of a real lamp in a camera)
• 2 glows on the screen at the same time (the 2 brightest seen; a glow fades in and out). Each layer shows one disc (16 to 128 pixels, 15 levels of light), moved by its scroll and colored by its palette: no CPU time per pixel
• The layers change when the image of the frame is displayed (not when the frame is computed): the glow stays on its lamp when the camera turns
• They use the VRAM bank B0 of the VDP2: the rotation screen (the 3D planes, see background.h) is hidden while the glows are on (for the places where the 3D planes are not seen: inside a building, underground...)
• A wall between the camera and a lamp hides its glow (see jo_3d_glows_set_occlusion())

Usage: jo_3d_glows_enable(true), jo_3d_glow_add() for each lamp, then jo_3d_glows_draw() at each frame after the camera (its matrix is the current matrix)

Bug

No known bugs.

Macro Definition Documentation

JO_3D_GLOW_MAX

#define JO_3D_GLOW_MAX

Max glows (lamps).

Function Documentation

jo_3d_glow_add()

int jo_3d_glow_add	(	const jo_pos3D_fixed *const	position,
		const unsigned char	r,
		const unsigned char	g,
		const unsigned char	b,
		const int	radius,
		const int	intensity )

Add a glow.

Parameters

position	Position (world)
r	Red (0 to 255): the color added at its middle with the intensity 256
g	Green
b	Blue
radius	Radius (world units): its size on the screen changes with its distance (16 to 128 pixels)
intensity	Intensity (0: off, 256: its color)

Returns

Id of the glow, -1 if there are too many

jo_3d_glow_set_color()

void jo_3d_glow_set_color	(	const int	id,
		const unsigned char	r,
		const unsigned char	g,
		const unsigned char	b )

Change the color of a glow.

Parameters

id	Id of the glow
r	Red (0 to 255)
g	Green
b	Blue

jo_3d_glow_set_intensity()

void jo_3d_glow_set_intensity	(	const int	id,
		const int	intensity )

Change the intensity of a glow (a lamp that flickers, an alarm).

Parameters

id	Id of the glow
intensity	Intensity (0: off, 256: its color)

jo_3d_glow_set_position()

void jo_3d_glow_set_position	(	const int	id,
		const jo_pos3D_fixed *const	position )

Move a glow.

Parameters

id	Id of the glow
position	Position (world)

jo_3d_glows_clear()

void jo_3d_glows_clear

(

void

)

Remove all the glows.

jo_3d_glows_draw()

void jo_3d_glows_draw

(

const jo_pos3D_fixed *const

camera

)

Place the glows seen from the camera (once per frame, after the camera: its matrix is the current matrix).

Parameters

camera

Position of the camera (world): the rays of the occlusion

Remarks

The layers change when the image of this frame is displayed

jo_3d_glows_enable()

bool jo_3d_glows_enable

(

const bool

enabled

)

Turn the glows on or off: the VDP2 layers (see the remarks of this file: the 3D planes are hidden while they are on).

Parameters

enabled

true: the glows are displayed (the first call builds their characters in the VRAM)

Returns

false if the VDP2 memory is full (the glows stay off)

jo_3d_glows_set_clip()

void jo_3d_glows_set_clip

(

bool(*

clip )(const jo_pos3D_fixed *const position, jo_3d_rect *const rect)

)

The glows are seen only in a rectangle of the screen: the rectangle where the place of the lamp is seen (a lamp in a room seen through a door: its glow stays in the door, see jo_cells_view_rect_at()). A window of the VDP2 cuts the disc to the rectangle.

Parameters

clip	Gives the rectangle where a point is seen, false if it is not seen; JO_NULL: the whole screen

jo_3d_glows_set_occlusion()

void jo_3d_glows_set_occlusion

(

bool(*

hit )(const jo_pos3D_fixed *const origin, const jo_pos3D_fixed *const dir, const jo_fixed max_t)

)

The walls hide the glows behind them (a ray from the camera to the lamp, a few each frame).

Parameters

hit	The ray from origin along dir (unit vector) hits something before max_t (Q16.16), JO_NULL: always seen

jo_3d_glows_set_rays()

void jo_3d_glows_set_rays	(	const int	light,
		const int	diagonal_light )

The light of the rays of the glows (the star around the disc), before jo_3d_glows_enable() (its characters are built then).

Parameters

light	Light of the 4 rays on the axes (0 to 256, in the middle of the glow; 150 by default, 0: no rays)
diagonal_light	Light of the 4 shorter rays on the diagonals (100 by default)