fix(camera): fix tearing and heavy pixelisation in zoom mode

Currently, the canvas was created at render size and elements where 
resized inside. Work a bit differenlty, by creating a canvas that have 
the view "true" size (meaning the scaled size), and draw everything at 
1:1 size inside. Then, when drawing the view canvas, resize the whole 
canvas at the multiplication of both scaling.

gamecore/modules/world/camera/init.lua

@@ -164,8 +164,8 @@ function CameraSystem:attachView(id)
     -- de position de camera pour afficher la carte par rapport à ces infos
       tx, ty  = self:getViewCoordinate(id)
       scale   = self:getViewScale(id) or 1
-    	tx = math.floor(tx) * -1 * scale
+    	tx = math.floor(tx) * -1
-    	ty = math.floor(ty) * -1 * scale
+    	ty = math.floor(ty) * -1
 
       local w, h = core.screen:getDimensions()
     end
@@ -173,25 +173,30 @@ function CameraSystem:attachView(id)
     love.graphics.push()
   	love.graphics.origin()
   	love.graphics.translate(math.floor(tx), math.floor(ty))
-    love.graphics.scale(view.scale, view.scale)
   end
 end
 
 function CameraSystem:detachView(id)
   if (id ~= nil) then
     local view = self:getView(id)
+    love.graphics.rectangle("fill", view.x-8, view.y-8, 16, 16)
     love.graphics.pop()
 
     love.graphics.setCanvas(self.current_canvas)
     local tx, ty  = self:getOnScreenViewCoordinate(id)
-    local scale   = core.screen:getScale()
+    local scale   = core.screen:getScale() * view.scale
+
     love.graphics.push()
   	love.graphics.origin()
   	love.graphics.translate(math.floor(tx), math.floor(ty))
     love.graphics.scale(scale, scale)
 
     love.graphics.draw(view.canvas)
+
+    local unscale = 1 / view.scale
+    love.graphics.scale(unscale, unscale)
     self:drawHUD(id)
+
     love.graphics.pop()
   end
 end
@@ -247,6 +252,16 @@ function CameraSystem:getOnScreenViewCenter(id)
   return core.screen:getScreenCoordinate(viewx, viewy)
 end
 
+function CameraSystem:setViewScale(id, scale)
+  local view = self:getView(id)
+
+  view.scale = scale
+
+  local _, _, w, h = self:getViewCoordinate(id)
+
+  view.canvas = love.graphics.newCanvas(math.ceil(w), math.ceil(h))
+end
+
 function CameraSystem:getViewScale(id)
   local view = self:getView(id)
 
@@ -337,7 +352,7 @@ function CameraSystem:followAllActors(id)
       local scalex = (maxX-minX)/ww
       local scaley = (maxY-minY)/hh
       scale = math.max(scale, scalex, scaley)
-      view.scale = 1/scale
+      self:setViewScale(id, 1/scale)
       self.world:resizeMap(ww * 3, hh * 3)
     end