cursor fix

I combined a lot of the comments to get things working better.  However, the preview graphic in the config page is still broken.  Perhaps some of these changes can be integrated into the next release if they work for most people.

Instructions:
Locate and open _Cursor.lua in NotePad, then copy and paste the code below, replacing everything currently in that file.  Save the file, then run WoW or do /reload if it is currently running.

--DJU: Sep 14, 2016 - Fixed scale/offset bug.
--                  - Fixed "GetModel is nil" bug.
--                  - Hid the cursor during mouse look (while right mouse button held).
--                  - Note: The preview graphic on the configuration page is still broken.
--                  (Search for "DJU" to see all my changes.)

-------------------------------------------------------------------------------
-- Localized Lua globals.
-------------------------------------------------------------------------------
local _G = getfenv(0)

-- Functions
local next = _G.next
local pairs = _G.pairs
local tonumber = _G.tonumber
local type = _G.type

-- Libraries
local table = _G.table

-------------------------------------------------------------------------------
-- AddOn namespace.
-------------------------------------------------------------------------------
local FOLDER_NAME = ...
local Version = GetAddOnMetadata(FOLDER_NAME, "Version"):match("^([%d.]+)")
_CursorOptions = nil
_CursorOptionsCharacter = {
	Cursors = {},
	Version = Version
}

local L = _CursorLocalization
local _Cursor = CreateFrame("Frame", "_Cursor")

-------------------------------------------------------------------------------
-- Variables
-------------------------------------------------------------------------------
local ActiveModels = {}
local InactiveModels = {}

-------------------------------------------------------------------------------
-- Constants
-------------------------------------------------------------------------------
_Cursor.DefaultModelSet = L.SETS["Energy beam"]
_Cursor.DefaultType = ""
_Cursor.DefaultValue = "spells\\errorcube" -- Used when cursor preset not found
_Cursor.ScaleDefault = 0.01 -- Baseline scaling factor applied before presets and custom scales

-- Set strings formatted as follows:
-- "Name|[Enabled]|Strata|[Type]|Value[|Scale][|Facing][|X][|Y]"
_Cursor.DefaultSets = {
	[L.SETS["Energy beam"]] = {
		-- Energy/lightning trail
		L.CURSORS["Layer 1"] .. "|1|TOOLTIP|Trail|Electric, blue",
		L.CURSORS["Layer 2"] .. "|1|FULLSCREEN_DIALOG|Particle|Fire, blue",
		L.CURSORS["Layer 3"] .. "||FULLSCREEN_DIALOG"
	},
	[L.SETS["Shadow trail"]] = {
		-- Cloudy shadow trail
		L.CURSORS["Layer 1"] .. "|1|TOOLTIP|Trail|Shadow|0.5",
		L.CURSORS["Layer 2"] .. "|1|FULLSCREEN_DIALOG|Particle|Shadow cloud",
		L.CURSORS["Layer 3"] .. "||FULLSCREEN_DIALOG",
	},
	[L.SETS["Face Melter (Warning, bright!)"]] = {
		-- Large red blowtorch
		L.CURSORS["Laser"] .. "|1|LOW||spells\\cthuneeyeattack|1.5|.4|32|13",
		L.CURSORS["Heat"] .. "|1|BACKGROUND||spells\\deathanddecay_area_base",
		L.CURSORS["Smoke"] .. "|1|BACKGROUND||spells\\sandvortex_state_base",
	}
}

-- Preset strings formatted as follows:
-- "Path[|Scale][|Facing][|X][|Y]"
_Cursor.Presets = {
	["Glow"] = {
		["Burning cloud, blue"] = "spells\\manafunnel_impact_chest|||4|-6",
		["Burning cloud, green"] = "spells\\lifetap_state_chest|||4|-6",
		["Burning cloud, purple"] = "spells\\soulfunnel_impact_chest|1|0|4|-6",
		["Burning cloud, red"] = "spells\\healrag_state_chest|||4|-6",
		["Cloud, black & blue"] = "spells\\enchantments\\soulfrostglow_high|4||8|-7",
		["Cloud, blue"] = "spells\\enchantments\\spellsurgeglow_high|6||10|-8",
		["Cloud, bright purple"] = "spells\\gouge_precast_state_hand|2.4||11|-9",
		["Cloud, corruption"] = "spells\\seedofcorruption_state|.9||9|-8",
		["Cloud, dark blue"] = "spells\\summon_precast_hand|2.7||9|-8",
		["Cloud, executioner"] = "spells\\enchantments\\disintigrateglow_high|4||8|-7",
		["Cloud, fire"] = "spells\\enchantments\\sunfireglow_high|5||10|-8",
		["Cloud, frost"] = "spells\\icyenchant_high|8||8|-8",
		["Ring, bloodlust"] = "spells\\bloodlust_state_hand|2.6||9|-8",
		["Ring, bones"] = "spells\\bonearmor_state_chest|.8||12|-9",
		["Ring, holy"] = "spells\\holy_precast_high_base|.8||9|-9",
		["Ring, pulse blue"] = "spells\\brillianceaura|.8||8|-8",
		["Ring, frost"] = "spells\\ice_precast_high_hand|1.9||11|-9",
		["Ring, vengeance"] = "spells\\vengeance_state_hand|2||9|-8",
		["Simple, black"] = "spells\\shadowmissile|2||5|-6",
		["Simple, green"] = "spells\\nature_precast_chest|||8|-8",
		["Simple, white"] = "spells\\enchantments\\whiteflame_low|4|5.3|10|-8",
		["Weather, lightning"] = "spells\\goblin_weather_machine_lightning|1.3||10|-11",
		["Weather, sun"] = "spells\\goblin_weather_machine_sunny|1.5|2.1|11|-9",
		["Weather, snow"] = "spells\\goblin_weather_machine_snow|1.5|2.1|11|-9",
		["Weather, cloudy"] = "spells\\goblin_weather_machine_cloudy|1.5|2.1|11|-9",
	},
	["Particle"] = {
		["Dust, arcane"] = "spells\\arcane_form_precast|1.1|.7|9|-11",
		["Dust, embers"] = "spells\\fire_form_precast|1.1|.7|9|-11",
		["Dust, holy"] = "spells\\holy_form_precast|1.1|.7|9|-11",
		["Dust, ice shards"] = "spells\\frost_form_precast|1.1|.7|9|-11",
		["Dust, shadow"] = "spells\\shadow_form_precast|1.1|.7|9|-11",
		["Fire"] = "spells\\demolisher_missile||2.2|11|-11",
		["Fire, blue"] = "spells\\fire_blue_precast_uber_hand|||6|-8",
		["Fire, fel"] = "spells\\fel_fire_precast_hand|||6|-8",
		["Fire, orange"] = "spells\\fire_precast_uber_hand|1.5||4|-6",
		["Fire, periodic red & blue"] = "spells\\incinerate_impact_base|.8||11|-10",
		["Fire, wavy purple"] = "spells\\incinerateblue_low_base|.25|2.3|11|-10",
		["Frost"] = "spells\\ice_precast_low_hand|2.5||8|-7",
		["Lava burst"] = "spells\\shaman_lavaburst_missile|.8||9|-7",
		["Leaves"] = "spells\\nature_form_precast|2.5|1|13|-11",
		["Periodic glint"] = "spells\\enchantments\\sparkle_a|4",
		["Plague cloud"] = "spells\\forsakencatapult_missile|1.5|2.3|10|-10",
		["Shadow cloud"] = "spells\\cripple_state_chest|.5||8|-8",
		["Spark, small white"] = "spells\\dispel_low_recursive|4",
		["Spark, small blue"] = "spells\\detectmagic_recursive|4",
		["Sparks, periodic healing"] = "spells\\lifebloom_state|||8|-8",
		["Sparks, red"] = "spells\\immolationtrap_recursive|4",
	},
	["Trail"] = {
		["Blue"] = "spells\\beartrap|.9||5|-6",
		["Electric, blue long"] = "spells\\lightningboltivus_missile|.1||4|-6",
		["Electric, blue"] = "spells\\lightning_precast_low_hand|||4|-6",
		["Electric, green"] = "spells\\lightning_fel_precast_low_hand|||4|-6",
		["Electric, yellow"] = "spells\\wrath_precast_hand|1.5||4|-6",
		["First-aid"] = "spells\\firstaid_hand|2||4|-6",
		["Freedom"] = "spells\\blessingoffreedom_state|.4||8|-8",
		["Ghost"] = "spells\\zig_missile|.7|1|8|-5",
		["Holy bright"] = "spells\\holy_missile_uber|.9||11|-9",
		["Long blue & holy glow"] = "spells\\alliancectfflag_spell|.9|2.3|1|-2",
		["Shadow"] = "spells\\shadow_precast_uber_hand|||4|-6",
		["Souls, small"] = "spells\\soulshatter_missile|1.7||5|-6",
		["Souls"] = "spells\\wellofsouls_base|.5||9|-8",
		["Sparkling, blue"] = "spells\\intervenetrail||2.4|7|-7",
		["Sparkling, light green"] = "spells\\sprint_impact_chest|1.3|.8|3|-4",
		["Sparkling, red"] = "spells\\chargetrail||2.4",
		["Sparkling, white"] = "spells\\ribbontrail",
		["Swirling, black"] = "spells\\shadow_impactdd_med_base|.5||5|-6",
		["Swirling, blood"] = "spells\\bloodbolt_chest|.5||5|-6",
		["Swirling, blue"] = "spells\\banish_chest_blue|.5||11|-9",
		["Swirling, holy"] = "spells\\holy_precast_uber_hand|||5|-6",
		["Swirling, nature"] = "spells\\rejuvenation_impact_base|.35||5|-6",
		["Swirling, poison"] = "spells\\banish_chest|.5||11|-9",
		["Swirling, purple"] = "spells\\banish_chest_purple|.5||11|-9",
		["Swirling, shadow"] = "spells\\banish_chest_dark|.5||11|-9",
		["Swirling, white"] = "spells\\banish_chest_white|.5||11|-9",
		["Swirling, yellow"] = "spells\\banish_chest_yellow|.5||11|-9",
	},
	["Breath"] = {
		["Arcane"] = "spells\\dragonbreath_arcane|.25|5.4",
		["Fire. blue"] = "spells\\dragonbreath_frost|.25|5.4",
		["Fire, fel"] = "spells\\fel_flamebreath|.5|5.5",
		["Fire, purple"] = "spells\\dragonbreath_shadow|.25|5.4",
		["Fire, red"] = "spells\\dragonbreath_fire|.25|5.4",
		["Frost"] = "spells\\flamebreath_blue|.5|5.5",
		["Frostfire"] = "spells\\flamebreathmff|.5|5.5",
		["Smoke"] = "spells\\corrosivesandbreath|.5|5.5",
	}
}

-------------------------------------------------------------------------------
-- Helpers
-------------------------------------------------------------------------------
local AddHideCondition, RemoveHideCondition
do
	local ActiveHideConditions = {}

	function AddHideCondition(conditionName)
		if not ActiveHideConditions[conditionName] then
			ActiveHideConditions[conditionName] = true
			_Cursor:Hide()
		end
	end

	function RemoveHideCondition(conditionName)
		if ActiveHideConditions[conditionName] then
			ActiveHideConditions[conditionName] = nil

			if next(ActiveHideConditions) == nil then
				_Cursor:Show()
			end
		end
	end
end

local function DisableModel(model)
	if not ActiveModels[model] then
		return
	end
	ActiveModels[model] = nil
	InactiveModels[model] = true

	model.X = nil
	model.Y = nil
	model:Hide()
	model:ClearModel()
end

local function EnableModel(model, cursorData)
	if ActiveModels[model] then
		DisableModel(model)
	end
	InactiveModels[model] = nil
	ActiveModels[model] = cursorData

	local cursor = ActiveModels[model]
	local scale = (cursor.Scale or 1.0) * _Cursor.ScaleDefault
	local facing = cursor.Facing or 0

	model.X = cursor.X or 0
	model.Y = cursor.Y or 0

	if #cursor.Type == 0 then -- Custom
		model:SetModel(cursor.Value .. ".mdx")
	else
		local presetType = _Cursor.Presets[cursor.Type]

		if not presetType or not presetType[cursor.Value] then
			cursor.Type = _Cursor.DefaultType
			cursor.Value = _Cursor.DefaultValue
			presetType = _Cursor.Presets[cursor.Type]
		end

		local path, scalePreset, facingPreset, x, y = ("|"):split(presetType[cursor.Value])
		model:SetModel(path .. ".mdx")
		model.X = model.X + (tonumber(x) or 0)
		model.Y = model.Y + (tonumber(y) or 0)

		scale = scale * (tonumber(scalePreset) or 1.0)
		facing = facing + (tonumber(facingPreset) or 0)
	end

	model:SetModelScale(scale)
	model:SetFacing(facing)
	model:SetFrameStrata(cursor.Strata)
	model:Show()
end

-------------------------------------------------------------------------------
-- Events
-------------------------------------------------------------------------------
_Cursor:RegisterEvent("ADDON_LOADED")
_Cursor:RegisterEvent("CINEMATIC_START")
_Cursor:RegisterEvent("CINEMATIC_STOP")
_Cursor:RegisterEvent("SCREENSHOT_FAILED")
_Cursor:RegisterEvent("SCREENSHOT_SUCCEEDED")

function _Cursor:SCREENSHOT_FAILED()
	RemoveHideCondition("Screenshot")
end

_Cursor.SCREENSHOT_SUCCEEDED = _Cursor.SCREENSHOT_FAILED

function _Cursor:CINEMATIC_START()
	AddHideCondition("Cinematic")
end

function _Cursor:CINEMATIC_STOP()
	RemoveHideCondition("Cinematic")
end

do
	local function VersionCompare(Version1, Version2) -- Compares delimited version strings
		if Version1 == Version2 then
			return 0
		end

		Version1 = {
			("."):split(Version1 or "")
		}

		Version2 = {
			("."):split(Version2 or "")
		}

		for index, Sub1 in ipairs(Version1) do
			local Sub2 = Version2[index]
			if not Sub2 or Sub1 > Sub2 then
				return 1
			elseif Sub1 < Sub2 then
				return -1
			end
		end
		return #Version1 - #Version2
	end

	function _Cursor:ADDON_LOADED(_, addonName)
		if addonName:lower() ~= FOLDER_NAME:lower() then
			return
		end

		_Cursor:UnregisterEvent("ADDON_LOADED")
		_Cursor.ADDON_LOADED = nil

		if not _CursorOptions then
			_CursorOptions = {
				Sets = CopyTable(_Cursor.DefaultSets)
			}
		end

		if _CursorOptions.Version ~= Version then
			if VersionCompare(_CursorOptions.Version, "3.1.0.2") < 0 then -- 3.1.0.2: Updated the Face Melter preset
				local Name = L.SETS["Face Melter (Warning, bright!)"]

				if _CursorOptions.Sets[Name] then
					_CursorOptions.Sets[Name] = CopyTable(_Cursor.DefaultSets[Name])
				end
			end

			_CursorOptions.Version = Version
		end

		_CursorOptionsCharacter.Version = Version

		if not _CursorOptionsCharacter.Cursors[1] then
			_Cursor.LoadSet(_Cursor.DefaultSets[_Cursor.DefaultModelSet])
		else
			_Cursor:UpdateModels()

			if _Cursor.Options then
				_Cursor.Options.Update()
			end
		end
	end
end

-------------------------------------------------------------------------------
-- Hooks.
-------------------------------------------------------------------------------
-- Hide during screenshots
_G.hooksecurefunc("Screenshot", function()
	AddHideCondition("Screenshot")
end)

-- Hide while FMV movies play
_G.MovieFrame:HookScript("OnShow", function()
	AddHideCondition("Movie") -- FMV movie sequence, like the Wrathgate cinematic
end)

_G.MovieFrame:HookScript("OnHide", function()
	RemoveHideCondition("Movie")
end)

-- Hook camera movement to hide cursor effects
--_G.hooksecurefunc("CameraOrSelectOrMoveStart", function()
--	AddHideCondition("Camera")
--end)
--
--_G.hooksecurefunc("CameraOrSelectOrMoveStop", function()
--	RemoveHideCondition("Camera")
--end)

-------------------------------------------------------------------------------
-- Scripts.
-------------------------------------------------------------------------------

--DJU uncommented:
do
	local UPDATE_INTERVAL = 0.250  --DJU changed (was 1)

	local TotalElapsed = 0
	local IsMouselooking = _G.IsMouselooking

	_G.CreateFrame("Frame"):SetScript("OnUpdate", function(self, elapsed)
		TotalElapsed = TotalElapsed + elapsed

		if TotalElapsed >= UPDATE_INTERVAL then
			TotalElapsed = 0

			if IsMouselooking() then
				AddHideCondition("Mouselook")
			else
				RemoveHideCondition("Mouselook")
			end
		end
	end)
end
--DJU^

_Cursor:SetScript("OnEvent", function(self, eventName, ...)
	return self[eventName](self, eventName, ...)
end)

_Cursor:SetScript("OnShow", function()
	for model in pairs(ActiveModels) do
        if model.GetModel then  --DJU added.
            local path = model:GetModel() -- Returns model table if unset

            if type(path) == "string" then
                model:SetModel(path)
            end
		end  --DJU added.
	end
end)

--[[DJU removed:
do
	local GetCursorPosition = _G.GetCursorPosition
--	local hypotenuse = (_G.GetScreenWidth() ^ 2 + _G.GetScreenHeight() ^ 2) ^ 0.5 * _G.UIParent:GetEffectiveScale()
	local hypotenuse = (_G.GetScreenWidth() ^ 0.5 + _G.GetScreenHeight() ^ 0.5) * _G.UIParent:GetEffectiveScale()
	local previousX, previousY

	_Cursor:SetScript("OnUpdate", function(self, elapsed)
		local cursorX, cursorY = GetCursorPosition()

		if cursorX == previousX and cursorY == previousY then
			return
		end

		for model in pairs(ActiveModels) do
			model:SetPosition((cursorX + model.X) / hypotenuse, (cursorY + model.Y) / hypotenuse, 0)
		end

		previousX = cursorX
		previousY = cursorY
	end)
end
]]

--DJU added (from blog posts):
do
	local GetCursorPosition = _G.GetCursorPosition

	--This is the maximum position that the cursor can have in the vertical dimension.
	local cursorYRange = 768
	--This is the maximum position that the effect can have in the vertical dimension.
	local effectYRange = 60
	--"scale" allows us to convert between the cursor space and the effect space.
	local scale = cursorYRange / effectYRange
	local previousX, previousY

	_Cursor:SetScript("OnUpdate", function(self, elapsed)
		local cursorX, cursorY = GetCursorPosition()
		if cursorX == previousX and cursorY == previousY then
			return
		end

		for model in pairs(ActiveModels) do
			--  ...Even the offsets are offset?
			local offsetX = model.X - 6    -- DJU changed (was 11).
			local offsetY = model.Y + 6    -- DJU changed (was 9).

			--Getting the effect size and removing the default that was applied earlier.
			--This makes it so that changing the size of the effect doesn't shift it.
			local cursorScale = model:GetModelScale() / _Cursor.ScaleDefault

			--Converting the cursor position into effect space.
			local posX = (cursorX + offsetX) / scale / cursorScale
			local posY = (cursorY + offsetY) / scale / cursorScale
			model:SetPosition(posX, posY, 0)
		end

		previousX = cursorX
		previousY = cursorY
	end)
end
--DJU^


--[[****************************************************************************
  * Function: _Cursor.LoadSet                                                  *
  * Description: Unpacks a set into the current settings.                      *
  ****************************************************************************]]
do
	local tempCursors = {}

	function _Cursor.LoadSet(set)
		local cursors = _CursorOptionsCharacter.Cursors

		-- Unload tables
		for index = 1, #cursors do
			local cursor = cursors[index]
			cursors[index] = nil
			tempCursors[cursor] = true
		end

		-- Unpack new data
		for index = 1, #set do
			local cursorData = set[index]
			local cursor = next(tempCursors) or {}
			tempCursors[cursor] = nil

			cursor.Name, cursor.Enabled, cursor.Strata, cursor.Type, cursor.Value, cursor.Scale, cursor.Facing, cursor.X, cursor.Y = ("|"):split(cursorData)
			cursor.Enabled = #cursor.Enabled > 0
			cursor.Type = cursor.Type or ""
			cursor.Value = cursor.Value or ""
			cursor.Scale = tonumber(cursor.Scale)
			cursor.Facing = tonumber(cursor.Facing)
			cursor.X = tonumber(cursor.X)
			cursor.Y = tonumber(cursor.Y)
			cursors[index] = cursor
		end

		_Cursor:UpdateModels()

		if _Cursor.Options then
			_Cursor.Options.Update()
		end
	end
end

--[[****************************************************************************
  * Function: _Cursor.SaveSet                                                  *
  * Description: Packs a set from the current settings.                        *
  ****************************************************************************]]
function _Cursor.SaveSet(set)
	table.wipe(set)

	local cursors = _CursorOptionsCharacter.Cursors
	for index = 1, #cursors do
		local cursorData = cursors[index]

		set[index] = ("|"):join(cursorData.Name, cursorData.Enabled and 1 or "",
			cursorData.Strata, cursorData.Type, cursorData.Value, cursorData.Scale or "",
			cursorData.Facing or "", cursorData.X or "", cursorData.Y or ""):gsub("|+$", "")
	end
end

do
	local ModelStrataLevels = {
		BACKGROUND = 0,
		LOW = 0,
		MEDIUM = 0,
		HIGH = 0,
		DIALOG = 0,
		FULLSCREEN = 0,
		FULLSCREEN_DIALOG = 0,
		TOOLTIP = 0
	}

	function _Cursor:UpdateModels()
		for Model in pairs(ActiveModels) do
			DisableModel(Model)
		end

		for strataName in pairs(ModelStrataLevels) do
			ModelStrataLevels[strataName] = 0
		end
		local cursors = _CursorOptionsCharacter.Cursors

		for index = 1, #cursors do
			local cursorData = cursors[index]

			if cursorData.Enabled then
				local model = next(InactiveModels)

				if not model then
					model = _G.CreateFrame("Model", "CursorModel" .. index, self)
					model:SetAllPoints(nil) -- Fullscreen
					model:Hide()
--					model:SetLight(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) -- Allows trails like warriors' intervene to work
				end
				EnableModel(model, cursorData)

				local strataLevel = ModelStrataLevels[cursorData.Strata] + 1
				ModelStrataLevels[cursorData.Strata] = strataLevel
				model:SetFrameLevel(strataLevel)
			end
		end
	end
end