Comment on ASCII characters are not pixels: a deep dive into ASCII rendering

• over_clox@lemmy.world ⁨1⁩ ⁨day⁩ ago

  Sure, have at it!

  Sorry it’s not a full complete dump with examples, but it’s programmed in QBasic 1.1 and converts raw RGB pixel data into equivalent closest matching color halftone onscreen characters. I designed it in mind with DOS text modes of either 80x25, 80x43, or 80x50 text modes, but I’m sure the technique can work with any text mode that can properly render the old DOS block characters. But, I’m betting that whatever device you’re using right now is almost certainly not configured to display the old DOS block characters as they were back in the day.

  Good luck!

  REM TEXTPSET.BAS
  REM over_clox - February 26, 2008
  
  DECLARE SUB DisplayRAW (FileName$, W%, H%)
  DECLARE SUB TextPSet (X%, Y%, R%, G%, B%)
  DECLARE SUB TextPixel (Red%, Green%, Blue%, Char$, FGround%, BGround%)
  DECLARE SUB HTMtoRGB (HTMColor$, Red%, Green%, Blue%)
  
  TYPE PaletteType
      R AS INTEGER
      G AS INTEGER
      B AS INTEGER
  END TYPE
  
  REDIM SHARED DOSPalette(15) AS PaletteType
  REDIM SHARED FakePalette(15, 7, 1 TO 3) AS PaletteType
  
  RESTORE
  FOR I% = 0 TO 15
      READ HTMColor$
      HTMtoRGB HTMColor$, R%, G%, B%
      DOSPalette(I%).R = R%
      DOSPalette(I%).G = G%
      DOSPalette(I%).B = B%
  NEXT
  
  FOR C% = 1 TO 3
      C2% = 4 - C%
      FOR B% = 0 TO 7
          FOR F% = 0 TO 15
              R1% = DOSPalette(F%).R: R2% = DOSPalette(B%).R
              G1% = DOSPalette(F%).G: G2% = DOSPalette(B%).G
              B1% = DOSPalette(F%).B: B2% = DOSPalette(B%).B
              FakePalette(F%, B%, C%).R = (R1% * C% + R2% * C2%) \ 4
              FakePalette(F%, B%, C%).G = (G1% * C% + G2% * C2%) \ 4
              FakePalette(F%, B%, C%).B = (B1% * C% + B2% * C2%) \ 4
          NEXT
      NEXT
  NEXT
  
  'MS-DOS Text Mode 16 Color Palette
  DATA 000000,0000AA,00AA00,00AAAA,AA0000,AA00AA,AA5500,AAAAAA
  DATA 555555,5555FF,55FF55,55FFFF,FF5555,FF55FF,FFFF55,FFFFFF
  
  CMD$ = COMMAND$
  IF CMD$ <> "" THEN
      DisplayRAW CMD$, 80, 25
  ELSE
      DisplayRAW "LOGO.RAW", 80, 25
  END IF
  
  'DEF SEG = &HB800: BSAVE "LOGO.BSV", 0, 4000
  
  COLOR 7, 0
  
  DO: Hit$ = UCASE$(INKEY$): LOOP WHILE Hit$ = ""
  
  SUB DisplayRAW (FileName$, W%, H%)
  
      FileNum% = FREEFILE
      OPEN FileName$ FOR BINARY AS FileNum%
      CLS : WIDTH W%, H%
      ScanLine$ = SPACE$(W% * 3)
      FOR Y% = 0 TO H% - 1
          GET #1, , ScanLine$
          FOR X% = 0 TO W% - 1
              R% = ASC(MID$(ScanLine$, X% * 3 + 1, 1))
              G% = ASC(MID$(ScanLine$, X% * 3 + 2, 1))
              B% = ASC(MID$(ScanLine$, X% * 3 + 3, 1))
              TextPSet X%, Y%, R%, G%, B%
          NEXT
      NEXT
      CLOSE FileNum%
  
  END SUB
  
  SUB HTMtoRGB (HTMColor$, Red%, Green%, Blue%)
      Red% = VAL("&H" + MID$(HTMColor$, 1, 2))
      Green% = VAL("&H" + MID$(HTMColor$, 3, 2))
      Blue% = VAL("&H" + MID$(HTMColor$, 5, 2))
  END SUB
  
  SUB TextPixel (Red%, Green%, Blue%, Char$, FGround%, BGround%)
      ' °±²Û (32,176,177,178,219)
     
      Diff% = 768: BGround% = 0
      FOR F% = 0 TO 15
          RDiff% = ABS(DOSPalette(F%).R - Red%)
          GDiff% = ABS(DOSPalette(F%).G - Green%)
          BDiff% = ABS(DOSPalette(F%).B - Blue%)
          NewDiff% = RDiff% + GDiff% + BDiff%
          IF NewDiff% < Diff% THEN
              Diff% = NewDiff%: Char$ = "Û": FGround% = F%
          END IF
      NEXT
  
      FOR C% = 1 TO 3
          C2% = 4 - C%
          FOR B% = 0 TO 7
              FOR F% = 0 TO 15
                  RDiff% = ABS(FakePalette(F%, B%, C%).R - Red%)
                  GDiff% = ABS(FakePalette(F%, B%, C%).G - Green%)
                  BDiff% = ABS(FakePalette(F%, B%, C%).B - Blue%)
                  NewDiff% = RDiff% + GDiff% + BDiff%
                  IF NewDiff% < Diff% THEN
                      Diff% = NewDiff%: Char$ = CHR$(175 + C%)
                      FGround% = F%: BGround% = B%
                  END IF
              NEXT
          NEXT
      NEXT
  
  END SUB
  
  SUB TextPSet (X%, Y%, Red%, Green%, Blue%)
      TextPixel Red%, Green%, Blue%, Char$, FGround%, BGround%
      LOCATE Y% + 1, X% + 1: COLOR FGround%, BGround%: PRINT Char$;
  END SUB
  

  source

  • kora@sh.itjust.works ⁨1⁩ ⁨day⁩ ago

    You are amazing. Thank you very much for delivering! Half of the fun is discovering how it works without examples so no need to apologise :^)

    I need to look into running QBasic on my M4. Unsure about my options for now. Worst case scenario I spin up a VM tomorrow.

    source

    • over_clox@lemmy.world ⁨1⁩ ⁨day⁩ ago

      Meh, DOSBox is plenty suitable enough, and QBasic is easy enough to find…

      winworldpc.com/product/qbasic/1x

      I can’t promise that DOSBox emulated results will give the exact color results as original old-school hardware on an old CRT, but results should still be mighty close.

      The raw input data files are pretty simple to generate with most graphics software, just downsample down to potato 80x25, then export to raw 888 RGB format.

      source