local ENABLE_FAILISH_ATTEMPT_AT_ANTI_ALIASING = false



local OVERLAY_WIDTH      = 256

local OVERLAY_HEIGHT     = 256

local OVERLAY_LINE_WIDTH = 5

local OVERLAY_LINE_COLOR = tocolor ( 0, 200, 0, 255 )

local OVERLAY_LINE_AA    = tocolor ( 0, 200, 0, 200 )



local linePoints  = { }

local renderStuff = { }



function removeLinePoints ( )

	linePoints = { }

	for name, data in pairs ( renderStuff ) do

		unloadTile ( name )

	end

end



function addLinePoint ( posX, posY )

	-- Calculate the row and column of the radar tile we will be targeting

	local row = 11 - math.floor  ( ( posY + 3000 ) / 500 )

	local col =      math.floor ( ( posX + 3000 ) / 500 )



	-- If it's off the map, don't bother

	if row < 0 or row > 11 or col < 0 or col > 11 then

		return false

	end



	-- Check the start position of the tile

	local startX = col * 500 - 3000

	local startY = 3000 - row * 500



	-- Now get the tile position (We don't want to calculate this for every point on render)

	local tileX = ( posX - startX ) / 500 * OVERLAY_WIDTH

	local tileY = ( startY - posY ) / 500 * OVERLAY_HEIGHT



	-- Now calulcate the ID and get the name of the tile

	local id   = col + row * 12

	local name = string.format ( "radar%02d", id )



	-- Make sure the line point table exists

	if not linePoints [ name ] then

		linePoints [ name ] = { }

	end



	-- Now add this point

	table.insert ( linePoints[name], { posX = tileX, posY = tileY } )



	-- Success!

	return true

end



function loadTile ( name )

	-- Create our fabulous shader. Abort on failure

	local shader = dxCreateShader ( "overlay.fx" )

	if not shader then

		return false

	end



	-- Create a render target. Again, abort on failure (don't forget to delete the shader!)

	local rt = dxCreateRenderTarget ( OVERLAY_WIDTH, OVERLAY_HEIGHT, true )

	if not rt then

		destroyElement ( shader )

		return false

	end



	-- Mix 'n match

	dxSetShaderValue ( shader, "gOverlay", rt )



	-- Start drawing

	dxSetRenderTarget ( rt )



	-- Get the points involved, and get the starting position

	local points = linePoints [ name ]

	local prevX, prevY = points [ 1 ].posX, points [ 1 ] .posY



	-- Loop through all points we have to draw, and draw them

	for index, point in ipairs ( points ) do

		local newX = point.posX

		local newY = point.posY



		if ENABLE_FAILISH_ATTEMPT_AT_ANTI_ALIASING then

			dxDrawLine ( prevX - 1, prevY - 1, newX - 1, newY - 1, OVERLAY_LINE_AA, OVERLAY_LINE_WIDTH )

			dxDrawLine ( prevX + 1, prevY - 1, newX + 1, newY - 1, OVERLAY_LINE_AA, OVERLAY_LINE_WIDTH )

			dxDrawLine ( prevX - 1, prevY + 1, newX - 1, newY + 1, OVERLAY_LINE_AA, OVERLAY_LINE_WIDTH )

			dxDrawLine ( prevX + 1, prevY + 1, newX + 1, newY + 1, OVERLAY_LINE_AA, OVERLAY_LINE_WIDTH )

		end



		dxDrawLine ( prevX, prevY, newX, newY, OVERLAY_LINE_COLOR, OVERLAY_LINE_WIDTH )



		prevX = newX

		prevY = newY

	end



	-- Now let's show our fabulous work to the commoners!

	engineApplyShaderToWorldTexture ( shader, name )



	-- Store the stuff in memories

	renderStuff [ name ] = { shader = shader, rt = rt }



	-- We won

	return true

end



function unloadTile ( name )

	destroyElement ( renderStuff[name].shader )

	destroyElement ( renderStuff[name].rt )

	renderStuff[name] = nil

	return true

end



addEventHandler ( "onClientHUDRender", getRootElement ( ),

	function ( )

		local visibleTileNames = table.merge ( engineGetVisibleTextureNames ( "radar??" ), engineGetVisibleTextureNames ( "radar???" ) )



		for name, data in pairs ( renderStuff ) do

			if not table.find ( visibleTileNames, name ) then

				unloadTile ( name )

			end

		end



		for index, name in ipairs ( visibleTileNames ) do

			if linePoints [ name ] and not renderStuff [ name ] then

				loadTile ( name )

			end

		end

	end

)