Arduboy2 Library
Sprites Class Reference

A class for drawing animated sprites from image and mask bitmaps. More...

#include <Sprites.h>

+ Collaboration diagram for Sprites:

Static Public Member Functions

static void drawExternalMask (int16_t x, int16_t y, const uint8_t *bitmap, const uint8_t *mask, uint8_t frame, uint8_t mask_frame)
 Draw a sprite using a separate image and mask array. More...
 
static void drawPlusMask (int16_t x, int16_t y, const uint8_t *bitmap, uint8_t frame)
 Draw a sprite using an array containing both image and mask values. More...
 
static void drawOverwrite (int16_t x, int16_t y, const uint8_t *bitmap, uint8_t frame)
 Draw a sprite by replacing the existing content completely. More...
 
static void drawErase (int16_t x, int16_t y, const uint8_t *bitmap, uint8_t frame)
 "Erase" a sprite. More...
 
static void drawSelfMasked (int16_t x, int16_t y, const uint8_t *bitmap, uint8_t frame)
 Draw a sprite using only the bits set to 1. More...
 

Detailed Description

A class for drawing animated sprites from image and mask bitmaps.

The functions in this class will draw to the screen buffer an image contained in an array located in program memory. A mask can also be specified or implied, which dictates how existing pixels in the buffer, within the image boundaries, will be affected.

A sprite or mask array contains one or more "frames". Each frame is intended to show whatever the sprite represents in a different position, such as the various poses for a running or jumping character. By specifying a different frame each time the sprite is drawn, it can be animated.

Each image array begins with values for the width and height of the sprite, in pixels. The width can be any value. The height must be a multiple of 8 pixels, but with proper masking, a sprite of any height can be created.

For a separate mask array, as is used with drawExternalMask(), the width and height are not included but must contain data of the same dimensions as the corresponding image array.

Following the width and height values for an image array, or from the beginning of a separate mask array, the array contains the image and/or mask data for each frame. Each byte represents a vertical column of 8 pixels with the least significant bit (bit 0) at the top. The bytes are drawn as 8 pixel high rows from left to right, top to bottom. When the end of a row is reached, as specified by the width value, the next byte in the array will be the start of the next row.

Data for each frame after the first one immediately follows the previous frame. Frame numbers start at 0.

Note

A separate SpritesB class is available as an alternative to this class. The only difference is that the SpritesB class is optimized for small code size rather than for execution speed. One or the other can be used depending on whether size or speed is more important.

Even if the speed is acceptable when using SpritesB, you should still try using Sprites. In some cases Sprites will produce less code than SpritesB, notably when only one of the functions is used.

You can easily switch between using the Sprites class or the SpritesB class by using one or the other to create an object instance:

Sprites sprites; // Use this to optimize for execution speed
SpritesB sprites; // Use this to (likely) optimize for code size
Note
In the example patterns given in each Sprites function description, a # character represents a bit set to 1 and a - character represents a bit set to 0.
See also
SpritesB

Definition at line 75 of file Sprites.h.

Member Function Documentation

void Sprites::drawErase ( int16_t  x,
int16_t  y,
const uint8_t *  bitmap,
uint8_t  frame 
)
static

"Erase" a sprite.

Parameters
x,yThe coordinates of the top left pixel location.
bitmapA pointer to the array containing the image frames.
frameThe frame number of the image to erase.

The data from the specified frame in the array is used to erase a sprite. To "erase" a sprite, bits set to 1 in the frame will set the corresponding pixel in the buffer to 0. Frame bits set to 0 will remain unchanged in the buffer.

image  before  after  (# = 1, - = 0)

-----  -----   -----
--#--  -----   -----
##-##  -----   -----
--#--  -----   -----
-----  -----   -----

image  before  after

-----  #####   #####
--#--  #####   ##-##
##-##  #####   --#--
--#--  #####   ##-##
-----  #####   #####

Definition at line 20 of file Sprites.cpp.

void Sprites::drawExternalMask ( int16_t  x,
int16_t  y,
const uint8_t *  bitmap,
const uint8_t *  mask,
uint8_t  frame,
uint8_t  mask_frame 
)
static

Draw a sprite using a separate image and mask array.

Parameters
x,yThe coordinates of the top left pixel location.
bitmapA pointer to the array containing the image frames.
maskA pointer to the array containing the mask frames.
frameThe frame number of the image to draw.
mask_frameThe frame number for the mask to use (can be different from the image frame number).

An array containing the image frames, and another array containing corresponding mask frames, are used to draw a sprite.

Bits set to 1 in the mask indicate that the pixel will be set to the value of the corresponding image bit. Bits set to 0 in the mask will be left unchanged.

image  mask   before  after  (# = 1, - = 0)

-----  -###-  -----   -----
--#--  #####  -----   --#--
##-##  ##-##  -----   ##-##
--#--  #####  -----   --#--
-----  -###-  -----   -----

image  mask   before  after

-----  -###-  #####   #---#
--#--  #####  #####   --#--
##-##  #####  #####   ##-##
--#--  #####  #####   --#--
-----  -###-  #####   #---#

Definition at line 9 of file Sprites.cpp.

void Sprites::drawOverwrite ( int16_t  x,
int16_t  y,
const uint8_t *  bitmap,
uint8_t  frame 
)
static

Draw a sprite by replacing the existing content completely.

Parameters
x,yThe coordinates of the top left pixel location.
bitmapA pointer to the array containing the image frames.
frameThe frame number of the image to draw.

A sprite is drawn by overwriting the pixels in the buffer with the data from the specified frame in the array. No masking is done. A bit set to 1 in the frame will set the pixel to 1 in the buffer, and a 0 in the array will set a 0 in the buffer.

image  before  after  (# = 1, - = 0)

-----  -----   -----
--#--  -----   --#--
##-##  -----   ##-##
--#--  -----   --#--
-----  -----   -----

image  before  after

-----  #####   -----
--#--  #####   --#--
##-##  #####   ##-##
--#--  #####   --#--
-----  #####   -----

Definition at line 15 of file Sprites.cpp.

void Sprites::drawPlusMask ( int16_t  x,
int16_t  y,
const uint8_t *  bitmap,
uint8_t  frame 
)
static

Draw a sprite using an array containing both image and mask values.

Parameters
x,yThe coordinates of the top left pixel location.
bitmapA pointer to the array containing the image/mask frames.
frameThe frame number of the image to draw.

An array containing combined image and mask data is used to draw a sprite. Bytes are given in pairs with the first byte representing the image pixels and the second byte specifying the corresponding mask. The width given in the array still specifies the image width, so each row of image and mask bytes will be twice the width value.

Bits set to 1 in the mask indicate that the pixel will be set to the value of the corresponding image bit. Bits set to 0 in the mask will be left unchanged.

image  mask   before  after  (# = 1, - = 0)

-----  -###-  -----   -----
--#--  #####  -----   --#--
##-##  ##-##  -----   ##-##
--#--  #####  -----   --#--
-----  -###-  -----   -----

image  mask   before  after

-----  -###-  #####   #---#
--#--  #####  #####   --#--
##-##  #####  #####   ##-##
--#--  #####  #####   --#--
-----  -###-  #####   #---#

Definition at line 30 of file Sprites.cpp.

void Sprites::drawSelfMasked ( int16_t  x,
int16_t  y,
const uint8_t *  bitmap,
uint8_t  frame 
)
static

Draw a sprite using only the bits set to 1.

Parameters
x,yThe coordinates of the top left pixel location.
bitmapA pointer to the array containing the image frames.
frameThe frame number of the image to draw.

Bits set to 1 in the frame will be used to draw the sprite by setting the corresponding pixel in the buffer to 1. Bits set to 0 in the frame will remain unchanged in the buffer.

image  before  after  (# = 1, - = 0)

-----  -----   -----
--#--  -----   --#--
##-##  -----   ##-##
--#--  -----   --#--
-----  -----   -----

image  before  after

-----  #####   #####  (no change because all pixels were
--#--  #####   #####  already white)
##-##  #####   #####
--#--  #####   #####
-----  #####   #####

Definition at line 25 of file Sprites.cpp.


The documentation for this class was generated from the following files: