background.h File Reference

Jo Engine Background definition and tools. More...

Go to the source code of this file.

Macros
#define	JO_SCROLL_TABLE_SIZE
	512 entries. One offset for each line because the background size is a 512x512 pixels by default.

Functions
static __jo_force_inline void	jo_set_background_8bits_sprite (jo_img_8bits *img, int palette_id, bool vertical_flip)
	Add 8 bits background sprite.
static __jo_force_inline void	jo_set_background_sprite (const jo_img *const img, const unsigned short left, const unsigned short top)
	Add background sprite.
static __jo_force_inline void	jo_clear_background (const jo_color color)
	Clear the background.
static __jo_force_inline void	jo_move_background (const int x, const int y)
	Move background (scrolling).
static __jo_force_inline void	jo_zoom_background2 (const float width_factor, const float height_factor)
	Zoom background width and height independently.
static __jo_force_inline void	jo_zoom_background (const float factor)
	Zoom background.
static __jo_force_inline void	jo_draw_background_line (int x0, int y0, int x1, int y1, const jo_color color)
	Draw a line using Bresenham's line algorithm.
static __jo_force_inline void	jo_draw_background_square (const int x, const int y, const short width, const short height, const jo_color color)
	Draw a square on the background.
static __jo_force_inline void	jo_put_pixel_in_background (const int x, const int y, const jo_color color)
	Put pixel in background using color.
static __jo_force_inline void	jo_put_pixel_in_background_rgb (const int x, const int y, unsigned char r, unsigned char g, unsigned char b)
	Put pixel in background using composite color.
static __jo_force_inline void	jo_enable_background_3d_plane (jo_color background_color)
	Enable 3D planes.
static __jo_force_inline void	jo_disable_background_3d_plane (jo_color background_color)
	Disable 3D planes.
static __jo_force_inline void	jo_background_3d_plane_a_img (jo_img_8bits *img, int palette_id, bool repeat, bool vertical_flip)
	Setup plane A.
static __jo_force_inline void	jo_background_3d_plane_b_img (jo_img_8bits *img, int palette_id, bool repeat, bool vertical_flip)
	Setup plane B.
static __jo_force_inline void	jo_background_3d_plane_far_limit (const int max_zoom_out)
	Hide the farthest part of the 3D planes (the background color is visible instead).
static __jo_force_inline void	jo_background_3d_plane_a_draw (const bool use_scroll_format_matrix)
	Draw plane A.
static __jo_force_inline void	jo_background_3d_plane_b_draw (const bool use_scroll_format_matrix)
	Draw plane B.
static __jo_force_inline void	jo_background_3d_plane_b_draw_flat (const int x, const int y)
	Draw plane B as a flat image, without perspective: a sky behind the plane A (sea, ground).
static __jo_force_inline int *	jo_enable_background_horizontal_line_scroll (void)
	Enable horizontal line scroll effect.
static __jo_force_inline void	jo_disable_background_horizontal_line_scroll (void)
	Disable horizontal line scroll effect.
static __jo_force_inline void	jo_compute_background_horizontal_line_scroll (unsigned short offset)
	Compute horizontal line scroll effect using specific offset.

Detailed Description

Jo Engine Background definition and tools.

Author

Johannes Fetz

Warning

▲ IF YOUR ARE FAMILIAR WITH SEGA SATURN HARDWARE, USE vdp2.h FUNCTIONS INSTEAD ▲

IT'S JUST A WRAPPER FOR THOSE WHO DON'T CARE ABOUT SCREEN SCROLL AND VDP2 USAGE

Bug

No known bugs.

Macro Definition Documentation

JO_SCROLL_TABLE_SIZE

#define JO_SCROLL_TABLE_SIZE

512 entries. One offset for each line because the background size is a 512x512 pixels by default.

Function Documentation

jo_background_3d_plane_a_draw()

__jo_force_inline void jo_background_3d_plane_a_draw ( const bool use_scroll_format_matrix )

static

Draw plane A.

Parameters

use_scroll_format_matrix

Convert current matrix to scroll format matrix

jo_background_3d_plane_a_img()

__jo_force_inline void jo_background_3d_plane_a_img ( jo_img_8bits * img, int palette_id, bool repeat, bool vertical_flip )

static

Setup plane A.

Parameters

img	8 bits 255 colors max image. (Width AND height must be a multiple of 8)
palette_id	palette id from TGA (see also jo_palette)
repeat	Repeat the plane infinitely.
vertical_flip	Flip image vertically

Warning

Image need to be clockwised rotated (right) because of an optimisation

jo_background_3d_plane_b_draw()

__jo_force_inline void jo_background_3d_plane_b_draw ( const bool use_scroll_format_matrix )

static

Draw plane B.

Parameters

use_scroll_format_matrix

Convert current matrix to scroll format matrix

jo_background_3d_plane_b_draw_flat()

__jo_force_inline void jo_background_3d_plane_b_draw_flat ( const int x, const int y )

static

Draw plane B as a flat image, without perspective: a sky behind the plane A (sea, ground).

Parameters

x	Horizontal position in the image of the left of the screen (pixels, the image is repeated horizontally)
y	Vertical position in the image of the top of the screen (pixels)

Remarks

The plane B is displayed where the plane A is transparent (above its horizon). Above the image, the top left cell (8 x 8 pixels) of the image is repeated (see jo_vdp2_draw_rbg0_plane_b_flat())

jo_background_3d_plane_b_img()

__jo_force_inline void jo_background_3d_plane_b_img ( jo_img_8bits * img, int palette_id, bool repeat, bool vertical_flip )

static

Setup plane B.

Parameters

img	8 bits 255 colors max image. (Width AND height must be a multiple of 8)
palette_id	palette id from TGA (see also jo_palette)
repeat	Repeat the plane infinitely.
vertical_flip	Flip image vertically

Warning

Image need to be clockwised rotated (right) because of an optimisation

jo_background_3d_plane_far_limit()

__jo_force_inline void jo_background_3d_plane_far_limit ( const int max_zoom_out )

static

Hide the farthest part of the 3D planes (the background color is visible instead).

Parameters

max_zoom_out

Biggest reduction of the texture (0: no limit, 16: the plane stops where 16 texels are in 1 pixel)

Remarks

Far away, a plane is very reduced and looks noisy: with a background color like the horizon, it fades in the distance

jo_clear_background()

__jo_force_inline void jo_clear_background ( const jo_color color )

static

Clear the background.

Parameters

color

Clear color

jo_compute_background_horizontal_line_scroll()

__jo_force_inline void jo_compute_background_horizontal_line_scroll ( unsigned short offset )

static

Compute horizontal line scroll effect using specific offset.

Parameters

offset

Offset in scroll table returned by jo_enable_background_horizontal_line_scroll()

jo_disable_background_3d_plane()

__jo_force_inline void jo_disable_background_3d_plane ( jo_color background_color )

static

Disable 3D planes.

Parameters

background_color

Color (ex: JO_COLOR_Red)

jo_disable_background_horizontal_line_scroll()

__jo_force_inline void jo_disable_background_horizontal_line_scroll ( void )

static

Disable horizontal line scroll effect.

jo_draw_background_line()

__jo_force_inline void jo_draw_background_line ( int x0, int y0, int x1, int y1, const jo_color color )

static

Draw a line using Bresenham's line algorithm.

Parameters

x0	horizontal location of the beginning of the line
y0	vertical location of the beginning of the line
x1	horizontal location of the end of the line
y1	vertical location of the end of the line
color	Color (ex: JO_COLOR_Red)

jo_draw_background_square()

__jo_force_inline void jo_draw_background_square ( const int x, const int y, const short width, const short height, const jo_color color )

static

Draw a square on the background.

Parameters

x	Square horizontal location
y	Square vertical location
width	Square width
height	Square height
color	Color (ex: JO_COLOR_Red)

jo_enable_background_3d_plane()

__jo_force_inline void jo_enable_background_3d_plane ( jo_color background_color )

static

Enable 3D planes.

Parameters

background_color

Color (ex: JO_COLOR_Red)

jo_enable_background_horizontal_line_scroll()

__jo_force_inline int * jo_enable_background_horizontal_line_scroll ( void )

static

Enable horizontal line scroll effect.

Returns

An array of 512 entries. One offset for each line because the background size is a 512x512 pixels by default.

Warning

Only works with 8 bits background image

jo_move_background()

__jo_force_inline void jo_move_background ( const int x, const int y )

static

Move background (scrolling).

Parameters

x	horizontal location
y	vertical location

jo_put_pixel_in_background()

__jo_force_inline void jo_put_pixel_in_background ( const int x, const int y, const jo_color color )

static

Put pixel in background using color.

Parameters

x	horizontal location
y	vertical location
color	Color (ex: JO_COLOR_Red)

jo_put_pixel_in_background_rgb()

__jo_force_inline void jo_put_pixel_in_background_rgb ( const int x, const int y, unsigned char r, unsigned char g, unsigned char b )

static

Put pixel in background using composite color.

Parameters

x	horizontal location
y	vertical location
r	Red color component
g	Green color component
b	Blue color component

jo_set_background_8bits_sprite()

__jo_force_inline void jo_set_background_8bits_sprite ( jo_img_8bits * img, int palette_id, bool vertical_flip )

static

Add 8 bits background sprite.

Parameters

img	8 bits 255 colors max image. (Width AND height must be a multiple of 8)
palette_id	palette id from TGA (see also jo_palette)
vertical_flip	Flip image vertically

Warning

Image need to be clockwised rotated (right) because of an optimisation

jo_set_background_sprite()

__jo_force_inline void jo_set_background_sprite ( const jo_img *const img, const unsigned short left, const unsigned short top )

static

Add background sprite.

Parameters

img	Pointer to an image struct
left	Left location
top	Top location

Remarks

To show a TGA file: jo_set_background_tga()

jo_zoom_background()

__jo_force_inline void jo_zoom_background ( const float factor )

static

Zoom background.

Parameters

factor

Zoom factor

jo_zoom_background2()

__jo_force_inline void jo_zoom_background2 ( const float width_factor, const float height_factor )

static

Zoom background width and height independently.

Parameters

width_factor	Width zoom factor
height_factor	Height zoom factor