!Hopper

I was wondering about the graphics files for the game hopper which is supplied in Diversions. Are they in a recognisable format? Is it possible to edit them using something like !Paint or maybe Gimp on the PC?

Cheers.

In the source, in the directory Datafiles.Graphics_Gen.Sprites are a number of sprite files. They’re all MODE 13 (some with mask). Many are 20×20. Heights are generally 20 or 40 pixels. Widths are 20, 32, 40, 88… as necessary.

Within Graphics_Gen are a number of programs beginning “Con_” or “Gen_”. Looking at the results for the Fly graphics, what this appears to be doing is:

• Strip out any sprite headers so only the raw data is available.
• Invert the mask if it exists (so &FF bytes become &00 and vice versa)
  I am guessing this is because the code blits the data directly to screen memory.

Ah, yes, it’s in the graphics module, function gfx_mask_sprites():

    for ( row = 0; row <= height; row ++ ) {
      for ( col = 0; col < width; col ++ ) {
        scr[col] = (scr[col] & mask[col]) | spr[col] ;
      }

You can edit them in !Paint. Software such as Gimp probably won’t understand the specifics of ancient format RISC OS sprites.
Once you’re done editing, run the appropriate conversion file to make the data that Hopper uses.

https://www.riscosopen.org/viewer/view/bsd/RiscOS/Sources/Apps/Diversions/Hopper/DataFiles/Graphics_Gen/

Thanks Rick.