In the previous part, we have implemented a simple game template that allowes users to control a pixel on the canvas by pressing arrow keys, in this part, we are going to add two more features to make it more like a game:
- physics (gravity)
- drawing charactures with bitmaps
First let's resieze our canvas. By default, its size is 24 by 24, and we can add an optional argument to the cls command to change its resolution.
cls 32
This will change the canvas to 32 pixels in width and 32 pixels in height.
v = v' + gt
Free Fall
let CANVAS_SIZE 32
let x 10
let y 10
let v 0
let G 1
jmp draw
#main_loop
/ -- calculate velocity --
add v $v $G
add y $y $v
jlt $y 30 velocity_done
sub v 0 $v
let y 30
#velocity_done
/ -- draw --
#draw
clr $CANVAS_SIZE
drw $x $y 1
slp 50
jmp main_loop
Bit Map
let CANVAS_SIZE 64
let x 10
let y 0
let v 0
let G 1
def draw_bit_map
let left $0
let top $1
let map '00044444000000444444444000ccc22020000c2c222022200c2cc222022200c2222000000002222220000044744744000444744744404444777744442247277274222227777772222277777777220077700777000bbb0000bbb0bbbb0000bbbb'
for i 16
for j 12
pol $map c
sub c $c $nil
ifg $c 96
sub c $c 87
els
sub c $c 48
fin
add xx $top $i
add yy $left $j
drw $yy $xx $c
nxt
nxt
end
jmp draw
#main_loop
/ -- calculate velocity --
add v $v $G
add y $y $v
jlt $y 48 velocity_done
sub v 0 $v
let y 48
#velocity_done
/ -- draw --
#draw
clr $CANVAS_SIZE
cal draw_bit_map $x $y
slp 50
jmp main_loop