config.ini and example.lua

build.zig

@@ -196,6 +196,8 @@ fn install_ly(allocator: std.mem.Allocator, io: std.Io, patch_map: PatchMap, ins
         try installText(io, patched_setup, config_dir, ly_config_directory, "setup.sh", .{ .permissions = .fromMode(0o755) });
 
         try installFile(io, "res/example.dur", config_dir, ly_config_directory, "example.dur", .{ .permissions = .fromMode(0o755) });
+
+        try installFile(io, "res/example.lua", config_dir, ly_config_directory, "example.lua", .{ .permissions = .fromMode(0o755) });
     }
 
     {

res/config.ini

@@ -25,6 +25,7 @@ allow_empty_password = true
 # colormix -> Color mixing shader
 # gameoflife -> John Conway's Game of Life
 # dur_file -> .dur file format (https://github.com/cmang/durdraw/tree/master)
+# lua -> user-made animation written in LuaJIT
 animation = none
 
 # Delay between each animation frame in milliseconds
@@ -298,6 +299,9 @@ login_defs_path = /etc/login.defs
 # no need to add `exec "$@"` at the end
 logout_cmd = null
 
+# The file pointing to the Lua file to be used when using the Lua animation option
+lua_animation_file = $CONFIG_DIRECTORY/ly/example.lua
+
 # General log file path
 # If null, syslog will be used instead
 ly_log = /var/log/ly.log

res/example.lua

@@ -0,0 +1,49 @@
+-- [[
+-- This is an example of using LuaJIT to create a custom animation in Ly, in this case a
+-- bouncing square that changes colors.
+--
+-- You are given the following `ly` table:
+-- {
+--	height: number -- The height of the terminal
+--	width: number -- The width of the terminal
+--	frame_delay: number -- The amount of frames to delay an update to the animation
+--	putCell(byte, fg, bg, x, y) -- Put the cell a buffer. This buffer will be drawn
+--                                 on screen after draw() is called. It will not clear
+--                                 itself automatically, see `ly.clear()`.
+--                                 All arguments to this function are numbers, and 
+--                                 must be in the unsigned 32-bit integer range: 0 to 2^32-1.
+--  clear() -- Clear the buffer.
+-- }
+-- ]]
+
+local SQUARE_WIDTH = 10
+local SQUARE_HEIGHT = 5
+
+local SQUARE_X = 0
+local SQUARE_Y = 0
+
+local SQUARE_VX = 1
+local SQUARE_VY = 1
+
+local timer = os.clock()
+local color = math.random(0xFFFFFF)
+
+function draw()
+	-- Rather than progressing the animation by frame, do it based on
+	-- seconds, like from os.clock(). 
+	if timer + 0.025 < os.clock() then
+		ly.clear()
+		SQUARE_X = SQUARE_X + SQUARE_VX
+		SQUARE_Y = SQUARE_Y + SQUARE_VY
+		for x = SQUARE_X, SQUARE_X + SQUARE_WIDTH do
+			for y = SQUARE_Y, SQUARE_Y + SQUARE_HEIGHT do
+				ly.putCell(string.byte(' '), 0, color, x, y)
+			end
+		end
+		if SQUARE_X <= 0 then SQUARE_VX = 1; color = math.random(0xFFFFFF) end
+		if SQUARE_X + SQUARE_WIDTH >= ly.width-1 then SQUARE_VX = -1; color = math.random(0xFFFFFF) end
+		if SQUARE_Y <= 0 then SQUARE_VY = 1; color = math.random(0xFFFFFF) end
+		if SQUARE_Y + SQUARE_HEIGHT >= ly.height-1 then SQUARE_VY = -1; color = math.random(0xFFFFFF) end
+		timer = os.clock()
+	end
+end

src/animations/Lua.zig

@@ -129,7 +129,7 @@ fn draw(self: *Lua) void {
             self.lua.pop(1);
             self.lua.pop(1);
             if (pos < 0) continue; // do not draw cells that underflow
-            Cell.init(@intCast(char), @intCast(fg), @intCast(bg))
+            Cell.init(@intCast(char), @intCast(@as(i32, @truncate(fg))), @intCast(@as(i32, @truncate(bg))))
                 .put(@rem(@as(usize, @intCast(pos)), self.width), @divFloor(@as(usize, @bitCast(pos)), self.width)) catch {};
         }
     } else {