STVN

A very simple visual novel engine for Atari ST on monochrome high-res mode.

Building

To build this, you need the following:

• GNU make
• m68k-atari-mintelf gcc toolchain
• vasmm68k_mot
• UPX for compression

Prerequistes

• Atari ST (STe if you want to use DMA SNDH files)
• 512KiB ST-RAM or more.
• Any TOS version should work (tested only on TOS 2.06 and EmuTOS)

Running

• Provide a script file following the documented syntax
• Edit STVN.INI to meet your needs: script file and SNDH memory buffer, which should be the size of your largest SNDH file
• Run STVN.PRG from GEM Desktop.

Key bindings

• 'Space' to advance
• 'q' Quit
• 's' Save state
• 'l' Load state
• 'b' Go back 1 text block
• 'h' Show help screen

STVN.INI settings

As a sample, use the following:

STEST.VNS
B20000

'S' line is the script file

'B' line is the SNDH buffer space

Defaults: STVN.VNS & 20000

Supported formats / limitations:

• For pictures: PI1/PI3 monochrome, uncompressed 32KiB files. The palette isn't used, only the first 25600 bytes are read (640x320 image, leaving 80 pixels for the text box, 1 "Sayer" line and 4 text lines)

• For audio: any SNDH with a working playback routine compatible with gwEm's sndhlib

Both can be gzipped.

• Savestates: 10 supported 10 VN choices "registers", adding more wouldn't be very hard. Scripts can be 999999 lines long.

• Rollback history up to 1000 entries, included in savestates.

All resource files must be placed in the 'data' subdirectory.

Syntax:

Each line starts with an operand, like: IATARI.PI3

Supported operands:

• 'W' : Wait for input

  This is where most interaction will happen.

  Like saving/loading, waiting for 'space', quitting, etc...

• 'I' : Change background image

  Syntax: I[file] like IFILE.PI3

  Expected format is PI3, can (should) be gzipped, and is loaded entirely before being copied to video memory.

  Only the first 320 lines are loaded and drawn, the rest of the screen being used for the text area.

  A few bytes can thus be saved, for example bv removing the 400-lines padding code in pbmtopi3 source.

  As the picture is loaded in RAM before being copied in vram, this operand will use 32000 bytes of RAM during operation, freed after.

  This will obviously erase all sprites and clear the internal sprite list.

• 'S' : Sayer change

  Syntax: Sname like SToyoyo

  Obviously, this will reset character lines to 0.

  This is used as the save pointer and will also reset the text box.

• 'T' : Text line

  Syntax: Ttext like THere's a text line

  Line wrapping is disabled, so make sure a line isn't more than 79 characters!

• 'P' : Change music

  Syntax: P[file] like PFILE.SND

  Expected format is SNDH, optionally ICE-packed and/or gzipped, and is loaded entirely before starting its playing routine.

  This uses gwEm's sndhlib code, which should be pretty robust, but I'm not responsible for bugged replay routines in SNDH files...

  ICE depacking is done with pack-ice found at https://github.com/larsbrinkhoff/pack-ice which is pretty slow but should be compatible with the vast majority of SNDH files.

  Note: Be sure to adjust the 'B' Line in STVN.INI to match the uncompressed size of your largest tune. The default is 20000 bytes.

• 'PS' : Stop music

• 'J' : Jump to label

  Syntax: J[label] like `JLBL1```

  A label 4 bytes sequence at the beginning of a line

• 'C' : Offer a choice and store it in a register

  Key '1' entered: store 0

  Key '2' entered: store 1

  Key '3' entered: store 2

  Key '4' entered: store 3

  Syntax: C[register number][Max choices] like C04 meaning "Get a choice between 1 and 4 and assign it to register 0"

  Also offer the same interactions as a 'W' line.

• 'R' : Redraw the background picture.

  More precisely, copy back the buffer of last loaded one into video memory.

  This will obviously erase all sprites and clear the internal sprite list.

• 'B' : Jump to label if register is set.

  Syntax: B[register number][Choice][label] like B02LBL1 meaning "if register 0 is at 2, jump to LBL1"

• 'D' : Wait the specified number of milliseconds (max 99999).

  Syntax: D[msec] like D2000

• 'A' : Load and draw a sprite in video memory.

  Syntax: A[XXX][YYY][file] like A000000TOYO.SPR

  The expected format is derived from XPM, can (should) be gzipped and is plotted as it's read.

  A converter script is provided.

  Screen boundary are checked during drawing and you can't draw on the text area.

  More precicely: X coordinates after 640 are ignored and Y coordinates after 320 ends the drawing routine.

  This can use quite some memory: 1 byte per pixel, allocated in 1024 bytes blocks, freed after operation.

  And this is still drawn slower than a full screen image.

  They're tracked as much as I could during load & back routines, so what should happen is:

  • If you load a save, both background & sprites ('A' lines) encoutered between the lasts 'I' or 'R' lines are drawn.
  • If you go back and neither background & sprites changes: nothing is drawn
  • If you go back and there's a background change, this will also trigger a sprite draw pass.
  • If you go back to the 'S' line just before a 'A' Line, it will trigger a draw pass too. This is by design: When the 'S' line happens, the sprite doesn't exist yet.

• 'E' : Manually erase the text box, reset character lines to 0

• 'F' : Erase the history and return to the start of the script

• 'V' : Set a register at a value

  Syntax: V[register number][Value] like V19 meaning "Set value 9 on register 1"

• 'X' : Trigger a visual effect.

  Syntax: X[XX] like X03

  Effects should (must) be followed by a 'I' line since they erase the background.

  01: Vertically fade to black from top to bottom, 2 lines by 2 lines

  02: Vertically fade to white from top to bottom, 2 lines by 2 lines

  03: 01 then 02

  04: 02 then 01

  05: Vertically fade to black from bottom to top, 2 lines by 2 lines

  06: Vertically fade to white from bottom to top, 2 lines by 2 lines

  07: 05 then 06

  08: 06 then 05

  09: Vertically fade to black from outer to inner, 2 lines by 2 lines

  10: Vertically fade to white from outer to inner, 2 lines by 2 lines

  11: 09 then 10

  12: 10 then 09

  13: Vertically fade to black from inner to outer, 2 lines by 2 lines

  14: Vertically fade to white from inner to outer, 2 lines by 2 lines

  15: 13 then 14

  16: 14 then 13

  17: Horizontally fade to black from left to right, 1 cell at a time

  18: Horizontally fade to white from left to right, 1 cell at a time

  19: 17 then 18

  20: 18 then 17

  21: Horizontally fade to black from right to left, 1 cell at a time

  22: Horizontally fade to white from right to left, 1 cell at a time

  23: 21 then 22

  24: 22 then 21

  25: Horizontally fade to black from edges to middle, 1 cell at a time

  26: Horizontally fade to black from edges to middle, 1 cell at a time

  27: 25 then 26

  28: 26 then 25

  29: Horizontally fade to black from middle to edges, 1 cell at a time

  30: Horizontally fade to black from middle to edges, 1 cell at a time

  31: 29 then 30

  32: 30 then 29

  33: Draw expanding black pseudo-circle from center using 16x32 pixel blocks

  34: Draw expanding white pseudo-circle from center using 16x32 pixel blocks

  35: 33 then 34

  36: 34 then 33

  37: Draw shrinking black pseudo-circle from edges using 16x32 pixel blocks

  38: Draw shrinking white pseudo-circle from edges using 16x32 pixel blocks

  39: 37 then 38

  40: 38 then 37

  98: Fade the image area to black

  99: Fade from black to an image

  Syntax: X99[file] like X99IMAGE.PI3