Tutorials › dbc Classic › 9

Sprites

A scooter dodging rocks on the sea: the start of any 2D game.

What you need

sea.bmpexamples/dbc/tutorials/sprite/

scooter.bmpexamples/dbc/tutorials/sprite/

rock.bmpexamples/dbc/tutorials/sprite/

A background

LOAD BITMAP loads a picture into an off-screen bitmap. Bitmap 0 is the screen, so switch back to it with SET CURRENT BITMAP, then COPY BITMAP the background onto it every frame:

sprites_background.dba excerptDownload

load bitmap "sea.bmp", 1
set current bitmap 0
...
rem every frame, the background covers the last one
copy bitmap 1, 0

Sprites

A sprite shows an image at a position. SPRITE creates it the first time and moves it after. Black pixels in the image are transparent.

sprites_sprite.dba excerptDownload

load image "scooter.bmp", 1
...
sprite 1, x#, h - 90, 1     : rem sprite number, x, y, image

Collisions

SPRITE HIT is 1 on the first frame two sprites touch; SPRITE COLLISION is 1 as long as they overlap. Use the first to count hits, the second to keep a shield on.

sprites.dbaDownload

rem Sprites - OpenDBC tutorial (DarkBASIC Classic)
rem Media: sea.bmp, scooter.bmp and rock.bmp from examples/dbc/tutorials/sprite
sync on : sync rate 60
w = screen width() : h = screen height()

load bitmap "sea.bmp", 1
set current bitmap 0
load image "scooter.bmp", 1
load image "rock.bmp", 2

rem Sprite 1 is the scooter; black pixels are transparent
x# = w / 2
sprite 1, x#, h - 90, 1

rem Sprite 2 is a rock falling from the top
rx = rnd(w - 48) : ry# = -50
sprite 2, rx, ry#, 2

hits = 0
do
   rem Draw the sea, then the sprites appear on top
   copy bitmap 1, 0

   rem Steer with the arrow keys, or follow the rock on your own
   if leftkey() = 1 then x# = x# - 5
   if rightkey() = 1 then x# = x# + 5
   if leftkey() + rightkey() = 0 then x# = x# + (rx - x#) * 0.02
   sprite 1, x#, h - 90, 1

   ry# = ry# + 4
   if ry# > h then ry# = -50 : rx = rnd(w - 48)
   sprite 2, rx, ry#, 2

   rem SPRITE HIT is 1 on the first frame two sprites touch
   if sprite hit(1, 2) > 0 then hits = hits + 1
   text 10, 10, "Hits: " + str$(hits)
   sync
loop

Try this

Several rocks with arrays: dim rockx(5).
Flip the scooter when it turns with MIRROR SPRITE.
Scroll the sea by copying the bitmap in two slices with the long form of COPY BITMAP.

The repository's rock_dodge.dba is the full game, scrolling sea included.