review pt 2 + BIG performance improvement

res/example.lua

@@ -1,17 +1,19 @@
 -- [[
--- This is an example of using LuaJIT to create a custom animation in Ly, in this case a
--- bouncing square that changes colors.
+-- This is an example of using LuaJIT to create a custom animation in Ly, in this case
+-- bouncing squares that change colors.
 --
 -- You are given the following `ly` table:
 -- {
 --	height: number -- The height of the terminal
 --	width: number -- The width of the terminal
---	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.
+--	putCell(byte, fg, bg, x, y) -- Draw a cell. 
+--      All arguments to this function are integers, and 
+--      must be in the unsigned 32-bit integer range: 0 to 2^32-1.
+--
+--      For arguments fg and bg: they are colors in the format
+--      0xSSRRGGBB, where SS is for styling. See your
+--      config.ini for more details.
+--
 --  clock() -- The time, in microseconds.
 -- }
 --
@@ -19,16 +21,21 @@
 -- 
 -- ]]
 
+-- You should probably copy FPS and FPS_COUNT into any future LuaJIT animations you create.
+local FPS_COUNT = 40
+local function FPS()
+	return (1/FPS_COUNT)*1000000
+end
+
+
 local SQUARE_WIDTH = 10
 local SQUARE_HEIGHT = 5
 
 local SQUARE_COUNT = 25
 
-local FPS = 60
-
 local squares = {}
 
-for i = 0, SQUARE_COUNT-1 do
+for i = 1, SQUARE_COUNT do
 	local vx = 1
 	local vy = 1
 	if math.random(1, 2) == 2 then vx = -vx end
@@ -46,17 +53,13 @@ local timer = ly.clock()
 
 function draw()
 	-- Rather than progressing the animation by frame, do it based on
-	-- seconds, like from ly.clock(). 
-	if timer + ((1/FPS)*1000000)< ly.clock() then
-		ly.clear()
+	-- seconds, via ly.clock(). In this timeframe, you can update the animation state.
+	-- DO NOT DRAW CELLS IN THIS TIMEFRAME. You will get flickering.
+
+	if timer + FPS() < ly.clock() then -- if this check passes, we can update the animation
 		for i, v in ipairs(squares) do
 			v.x = v.x + v.vx
 			v.y = v.y + v.vy
-			for x = v.x, v.x + SQUARE_WIDTH do
-				for y = v.y, v.y + SQUARE_HEIGHT do
-					ly.putCell(string.byte(' '), 0, v.color, x, y)
-				end
-			end
 			if v.x <= 0 then v.vx = 1; v.color = math.random(0xFFFFFF) end
 			if v.x + SQUARE_WIDTH >= ly.width-1 then v.vx = -1; v.color = math.random(0xFFFFFF) end
 			if v.y <= 0 then v.vy = 1; v.color = math.random(0xFFFFFF) end
@@ -64,4 +67,13 @@ function draw()
 		end
 		timer = ly.clock()
 	end
+
+
+	for i, v in ipairs(squares) do
+		for x = v.x, v.x + SQUARE_WIDTH do
+			for y = v.y, v.y + SQUARE_HEIGHT do
+				ly.putCell(string.byte(' '), 0, v.color, x, y)
+			end
+		end
+	end
 end