scene/mainmenu: use a canvas for the repeating background

imperium-porcorum.love/scenes/debugmenu/init.lua

@@ -10,7 +10,7 @@ local bannerAnim = 0
 function MainMenu:new()
   MainMenu.super.new(self)
 
-  assets:setBackground( "back" )
+  self:createBackground("assets/backgrounds/back.png")
   menus:reset()
   assets:clearFonts()
   assets:addFont("small", "!\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~ ", 1)
@@ -35,6 +35,21 @@ function MainMenu:new()
   self:register()
 end
 
+function MainMenu:createBackground( filename )
+  local backAsset = love.graphics.newImage( filename )
+  self.background = love.graphics.newCanvas(424, 240)
+  love.graphics.setCanvas( self.background )
+  local w, h = backAsset:getDimensions()
+
+  for i=1, math.ceil(424 / w) do
+    for j=1,math.ceil(240/ h) do
+      love.graphics.draw(backAsset, (i-1)*w, (j-1)*h, 0, 1, 1)
+    end
+  end
+
+  love.graphics.setCanvas( )
+end
+
 function MainMenu:update(dt)
   MainMenu.super.update(self, dt)
   lovebird.update()
@@ -55,7 +70,7 @@ function MainMenu:mousepressed( x, y, button, istouch )
 end
 
 function MainMenu:draw()
-  assets:drawBackground()
+  love.graphics.draw(self.background)
   assets.sprites["emblem"]:draw(1, 240, 272/2-32, 0, 1, 1, 330/2, 192/2)