First BASIC program (since the late 80s)

I have written something yesterday that goes in the same direction:

screen 14
stars = 150

dim star_x(stars)
dim star_y(stars)
dim star_z(stars)
dim star_v(stars)
dim star_color(stars)

for i=0 to stars
  call new_star(i)
next

do
  vsync
  cls
  for i=0 to stars
    star_z(i) = star_z(i) - star_v(i)
    if star_z(i) <= 0 then
      call new_star(i)
    endif
    x = star_x(i) / star_z(i) + psize(0) / 2
    y = star_y(i) / star_z(i) + psize(1) / 2
    if x < 0 or x >= psize(0) or y < 0 or y >= psize(1) then
      call new_star(i)
    endif
    pset x, y, star_color(i)
  next
loop

proc new_star(n)
  @z = @n + 1
  star_x(@n) = -30000 + rnd(60000)
  star_y(@n) = -30000 + rnd(60000)
  star_z(@n) = @z
  star_v(@n) = 2 + int(rnd(0) mod 2)
  star_color(@n) = rgb(255 - @z, 255 - @z, 255 - @z)
  return

While I was at it, I have fixed PSET not to throw an error when drawing pixels that are outside screen limits, and CLS to properly clear the screen in modes where the screen dimensions are not divisible by the font size.

Dmian I think you are confusing INKEY and KEY. It should be k=KEY(75) (75 being the key code for the K key).

Dmian I should also say that if you ever need to break out of a program, ctrl-c should always work and saves you from losing whatever's in memory by reseting.

Dmian You're right, I'm misreading the reference entry for INKEY. I thought it was something to do with converting characters to keycodes.

I just tried the starfield with both 1920x1080 (HDMI) and 1280x1024 (DVI), and it works perfectly fine, VSYNC and Ctrl-C included.

Could you do me a favor and try this with basicengine-firmware-h3-v0.89-167-g730c.zip as well as with a current build and see if there is any difference?

I have recently changed the LCD interrupt to use vblank instead of the scan line trigger because that gives more time for rendering the next frame. I have no idea why Charlie used the scan line instead of vblank; who knows, maybe there is something broken with it.

That said, in Engine BASIC pretty much everything is timed off the LCD controller interrupt, and if there were a problem with it, it would break the entire system, not just a few select features...

[BTW, the reset button stopped working for me all of a sudden because the system failed to boot off the SD card after a reset. It worked perfectly fine just days ago, with the same SD cards and the same board. Anyway, updating the SPL to v2017.05 fixed it for me, and I have therefore pushed a new SPL binary to the allwinner-bare-metal repository. There won't be a nightly build until I commit some change to the basicengine-firmware repo, though.]

Dmian
I tried your code on the H3 and it ran as expected, exiting when a key is pressed. I also tried on the original hardware and it worked as well, all I did was remove the screen commands from line 10 and line 70. I'll try again on the H3 after I update the firmware.

uli
I love the starfield program. The last time I tried using local variables with an array in a procedure it gave me a ton of issues. I assumed it was just not doable based on the warning I saw in the manual but it looks like I'll have to play around with it more.

Dmian AND in basic is a bitwise operation, so: "IF p (being 8 if pressing up) AND UP (which is a synonym for 8)" should return 8 if they match. The "<" operator will return either -1 or 0, but if you AND that with the 8, you would get 0. You need to convert the first part to a boolean to be able to AND them in the way you want, so something like "IF p AND UP <> 0..."

Dmian
In the reference manual for MOVE SPRITE: "sprites that are placed completely outside the dimensions of the current screen mode will not be drawn"
I wonder if this is not taking account of the differences in H3's screen modes?