Create ModCharts.md

ModCharts.md

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+# Kade Engine Lua Mod Chart Documentation
+
+In the latest version of Kade Engine we introduced Mod Charts. Mod Charts are a way of changing gameplay without hard coded values, this is achieved by using the Lua Scripting language to create script files that run during runtime.
+
+All files **are located in** `assets/data/song/modchart.lua`
+
+Lua code will only be ran if that file exists.
+
+
+
+### Examples
+
+Full Example
+
+```lua
+function start (song)
+	print("Song: " .. song .. " @ " .. bpm .. " donwscroll: " .. downscroll)
+end
+
+
+function update (elapsed) -- example https://twitter.com/KadeDeveloper/status/1382178179184422918
+	local currentBeat = (songPos / 1000)*(bpm/60)
+		for i=0,7 do
+			_G['strum'..i..'X'] = _G['defaultStrum'..i..'X'] + 32 * math.sin((currentBeat + i*0.25) * math.pi)
+			_G['strum'..i..'Y'] = _G['defaultStrum'..i..'Y'] + 32 * math.cos((currentBeat + i*0.25) * math.pi)
+		end
+end
+
+function beatHit (beat)
+   -- do nothing
+end
+
+function stepHit (step)
+	-- do nothing
+end
+
+print("Mod Chart script loaded :)")
+```
+
+Spinning Receptor Example
+
+```lua
+function update (elapsed)
+		for i=0,7 do
+			_G['strum'..i..'Angle'] = _G['strum'..i..'Angle'] + 15
+		end
+end
+```
+
+Spinning Hud Example
+
+```lua
+function update (elapsed)
+	camHudAngle = camHudAngle + 0.005
+end
+```
+
+Spin at a specific part of the song
+
+```lua
+function update (elapsed)
+	if curStep >= 352 and curStep < 400 then
+		local currentBeat = (songPos / 1000)*(bpm/60)
+		for i=0,7 do
+			_G['strum'..i..'X'] = _G['defaultStrum'..i..'X'] + 32 * math.sin((currentBeat + i*0.25) * math.pi)
+			_G['strum'..i..'Y'] = _G['defaultStrum'..i..'Y'] + 32 * math.cos((currentBeat + i*0.25) * math.pi)
+		end
+	else
+    	_G['strum'..i..'X'] = _G['defaultStrum'..i..'X']
+        _G['strum'..i..'Y'] = _G['defaultStrum'..i..'Y']
+    end
+end
+```
+
+Showing/Hiding receptors/the hud
+
+```lua
+function start (song)
+    showOnlyStrums = true -- remove all hud elements besides notes and strums
+    _G['strumLine1Visible'] = false -- remove the first line of strums (the ai notes)
+end
+```
+
+
+
+### Available Hooks
+
+Current calls to functions include,
+
+|  Name   |   Arguments    |                         Description                          |
+| :-----: | :------------: | :----------------------------------------------------------: |
+|  start  |   Song Name    |              Get's called when the song starts               |
+| update  | Elapsed frames |       Get's called every frame (after the song starts)       |
+| stepHit |  Current Step  | Get's called when ever a step hits (steps are in between beats, aka 4 steps are in a beat) |
+| beatHit |  Current Beat  |              Get's called when ever a beat hits              |
+
+
+
+### Global Variables
+
+Kade Engine provides a list of global variables to be used in the lua scripting interface.
+
+|        G Name        | Type  |                         Description                          |
+| :------------------: | :---: | :----------------------------------------------------------: |
+|         bpm          | Float |                 The current BPM of the song                  |
+|        fpsCap        |  Int  |           The current FPS Cap (set by the player)            |
+|      downscroll      | Bool  |          Whether the player is in downscroll or not          |
+|       hudZoom        | Float |      The amount of zoom the Hud should be zoomed in/out      |
+|      cameraZoom      | Float |  The amount of zoom the Main Camera should be zoomed in/out  |
+|     cameraAngle      | Float |       The angle that the Main Camera should be rotated       |
+|     camHudAngle      | Float |           The angle that the Hud should be rotated           |
+|    followXOffset     | Float | The x offset to be added when the camera moves between a character |
+|    followYOffset     | Float | The y offset to be added when the camera moves between a character |
+|    showOnlyStrums    | Bool  |    Whether to show the Hud and Strums or only the Strums     |
+|  strumLine1Visible   | Bool  |         Whether to show the first strum line or not          |
+|  strumLine2Visible   | Bool  |         Whether to show the secondstrum line or not          |
+|      strum0-7X       | Float | (0-7 is strum0,strum1,strum2,etc) get/set the X coordinate for the strum |
+|      strum0-7Y       | Float | (0-7 is strum0,strum1,strum2,etc) get/set the Y coordinate for the strum |
+|    strum0-7Angle     | Float | (0-7 is strum0,strum1,strum2,etc) get/set the Angle for the strum |
+|   defaultStrum0-7X   | Float | (0-7 is strum0,strum1,strum2,etc) get the default X coordinate for the strum |
+|   defaultStrum0-7Y   | Float | (0-7 is strum0,strum1,strum2,etc) get the default Y coordinate for the strum |
+| defaultStrum0-7Angle | Float | (0-7 is strum0,strum1,strum2,etc) get the default Angle for the strum |
+