LTRO-1 Fantasy Console (Lospec Jam 1)

Overview

• Lua based "fantasy console" LTRO-1
• 240x135 pixel screen resolution
• 10 color display
• 7 button controller
• 2 channel "chip-tune" synthesizer
• graphics / sprites are simple Lua strings
• music / sound effects are simple Lua strings
• More info here https://itch.io/jam/lospec-jam-1
• integrated sprite editor
• Public Domain :)
• SDL2 is the only external dependency

Functions

• F1: resume with the Lua script
• F2: enter sprite editor

Lua Script

The game is programmed using the Lua (http://www.lua.org) programming language. LTRO-1 will include the newest Lua 5.4.3 as its runtime.

Sprite Editor

There is a very simple sprite editor in LTRO-1. You can draw 12x12 sprites and export/import it to/from the clipboard. Sou you can simply paste the exported string right into your Lua script.

Programming API

ltro.quit()

Forces the fantasy console to quit immediately.

ltro.btn(button)

Returns true if button is pressed, false otherwise. Valid strings for button are:

• up, down, left, right for d-pad
• a, b for buttons
• start for the extra button

if ltro.btn('a') then
    -- do something with a
end

ltro.btnp(button)

Returns true if button is pressed once, false otherwise. Valid strings for button are:

• up, down, left, right for d-pad
• a, b for buttons
• start for the extra button

if ltro.btnp('a') then
    -- do something with a
end

ltro.clearcolor([color])

If color is given, it will be set as the new default clear color. It also affects the non-drawable area around the screen, when the window has not 16:9 aspect ratio. Always returns the current clear color.

local color = ltro.clearcolor() -- get the current clear color
ltro.clearcolor(5) -- set new clear color

ltro.clear([color])

Clears the scren with the given color. If no color is given, the default clear color will be used. Returns nothing.

ltro.clear() -- clear with default clear color
ltro.clear(9) -- clear with color 9

ltro.pixel(color, x, y)

Draw a single pixel with color at x, y. Returns nothing.

ltro.line(color, x0, y0, x1, y1)

Draw a line with color from x0, y0 to x1, y1. Returns nothing.

ltro.rect(color, x0, y0, x1, y1 [, fill])

Draw a rectangle with color from x0, y0 to x1, y1. If fill is not falsy it will fill the rectangle. Returns nothing.

ltro.circle(color, x0, y0, radius, [, fill])

Draw a circle with color at x0, y0 in radius size. If fill is not falsy it will fill the circle. Returns nothing.

ltro.print(color, x, y, text)

Print the given ASCII text with color at x, y. You can use all 256 glyphs from the standard IBM-PC. Returns nothing.

ltro.draw(image, x, y [, mask])

Draws the given image string to x, y. If mask is given, all colors with that index will be transparent. The image string has a special format. The first two characters denote the width of the image. The next two characters the height. Then follow all the pixels as single characters ranging from 0-9.

Example: 10010123456789 This is an image, 10 pixels width and 1 pixel height. Containing all 10 colors.

ltro.draw('10010123456789', 0, 0) -- draw this example to the screen

ltro.gain([gain])

If gain is given it will se the current volume for the audio output (range 0.0 - 1.0). Always returns the current audio volume.

local gain = ltro.gain() -- just query the current audio volume
ltro.gain(0.5) -- set volume to 50%

ltro.play(channel, mml)

Starts the playback of the given MML (https://en.wikipedia.org/wiki/Music_Macro_Language) string on audio channel. Returns nothing.

Remarks to MML:

Command	Function
cdefgab	Play the corresponding note. Sharp notes are appeded with + or #, flat notes with -. A length value might follow. Example: c+8 Play C# as 1/8.
p, r	Pause the playback
o	Set the octave (0 - 7)
<, >	Go one octave down or up
l	Sets the default note length
t	Sets the tempo in beats per minute
m	Set the PSG mode: 5 50% pulse wave, 2 25% pulse wave, 1 12.5% pulse wave. Example: m2 sets the playback to 25% pulse wave.

ltro.play(1, 'cdefgab>c') -- just plays one octave :)

ltro.stop(channel)

Immediately stops the playback for the given audio channel (1 - 2). Returns nothing.

ltro.stop(1) -- stop audio channel 1

Update Log

0.5.0

• fixed package creation for Emscripten/Windows
• added rudimentary sprite editor (can be accessed with F2)

0.4.0

• renamed "init.lua" to "game.lua"
• added 3 types of pulse wave generators

0.3.0

• added HTML5/JavaScript port (Emscripten)

0.2.0

• added simple game controller support
• included Windows build (MinGW 64)

0.1.0

• first implementation