From 882f98bf40910fe2adaeb772c1f78f8791d456d8 Mon Sep 17 00:00:00 2001
From: Kazhnuz <antoine@sortilege.net>
Date: Mon, 29 Apr 2019 15:03:28 +0200
Subject: [PATCH] modules/world: add a way to link the camera to an actor

---
 gamecore/modules/world/actors/actor2D.lua |  8 +++++
 gamecore/modules/world/baseworld.lua      |  8 ++++-
 gamecore/modules/world/camera.lua         | 41 ++++++++++++++++++++++-
 3 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/gamecore/modules/world/actors/actor2D.lua b/gamecore/modules/world/actors/actor2D.lua
index 2faf328..d7c722d 100644
--- a/gamecore/modules/world/actors/actor2D.lua
+++ b/gamecore/modules/world/actors/actor2D.lua
@@ -161,6 +161,14 @@ end
 -- DRAW FUNCTIONS
 -- Draw the actors.
 
+function Actor2D:getCenter()
+  return (self.x + (self.w / 2)), (self.y + (self.h / 2))
+end
+
+function Actor2D:getViewCenter()
+  return self:getCenter()
+end
+
 function Actor2D:draw()
   -- here will be update actions
 end
diff --git a/gamecore/modules/world/baseworld.lua b/gamecore/modules/world/baseworld.lua
index 5a0aee8..df0dfcc 100644
--- a/gamecore/modules/world/baseworld.lua
+++ b/gamecore/modules/world/baseworld.lua
@@ -118,12 +118,17 @@ function BaseWorld:initPlayers()
   self.players = {}
 end
 
-function BaseWorld:addPlayer(actor, sourceid)
+function BaseWorld:addPlayer(actor, sourceid, haveCam)
   local player = {}
   player.actor    = actor
   player.sourceid = sourceid or 1
 
   table.insert(self.players, player)
+
+  if (haveCam) then
+    local xx, yy = player.actor:getViewCenter()
+    self.cameras:addView(xx, yy, player.actor)
+  end
 end
 
 function BaseWorld:sendInputToPlayers(actor)
@@ -174,6 +179,7 @@ function BaseWorld:update(dt)
   self:updateMap(dt)
   self:sendInputToPlayers(dt)
   self:updateActors(dt)
+  self.cameras:update(dt)
 end
 
 function BaseWorld:updateActors(dt)
diff --git a/gamecore/modules/world/camera.lua b/gamecore/modules/world/camera.lua
index 263e4db..359a56a 100644
--- a/gamecore/modules/world/camera.lua
+++ b/gamecore/modules/world/camera.lua
@@ -143,7 +143,7 @@ end
 -- WRAPPER and UTILS
 -- Access data from the views
 
-function CameraSystem:addView(x, y)
+function CameraSystem:addView(x, y, target)
   if (#self.views.list < SCREEN_LIMIT) then
     local id = #self.views.list + 1
     local view = {}
@@ -156,6 +156,7 @@ function CameraSystem:addView(x, y)
     view.cam    = View(view.pos.x, view.pos.y, 1, 0, true)
     -- TODO: add a target system in order to make a camera able
     -- to target a specific object
+    view.target = target
 
     table.insert(self.views.list, view)
     self.views.width, self.views.height = self:getViewsDimensions()
@@ -234,6 +235,44 @@ function CameraSystem:getViewScale(id)
   return cam.scale
 end
 
+-- UPDATE and MOVE functions
+-- Move and update the camera system
+
+function CameraSystem:update(dt)
+  for i,v in ipairs(self.views.list) do
+    self:followActor(i)
+  end
+end
+
+function CameraSystem:moveView(id, x, y)
+  self.views.list[id].pos.x = x
+  self.views.list[id].pos.y = y
+
+  self:computeCamPosition(id)
+end
+
+function CameraSystem:computeCamPosition(id)
+  local decalx = self.views.list[id].pos.onScreen.x
+  local decaly = self.views.list[id].pos.onScreen.y
+
+  local realx  = self.views.list[id].pos.x
+  local realy  = self.views.list[id].pos.y
+
+  self.views.list[id].cam.x = realx - decalx
+  self.views.list[id].cam.y = realy - decaly
+end
+
+function CameraSystem:followActor(id)
+  local view = self:getView(id)
+
+  if view.target ~= nil then
+    local x, y = view.target:getViewCenter()
+    x = math.floor(x)
+    y = math.floor(y)
+    self:moveView(id, x, y)
+  end
+end
+
 function CameraSystem:drawDebugViewBox()
   for i=1, #self.views.list do
     local viewx, viewy, vieww, viewh = self:getOnScreenViewCoordinate(i)