[Solved]love.graphics.translate

[Dr.Tyler O.]

I have a project that I am working in which the camera follows the center of the player. But, in attempting to debug the game by displaying some variables on the screen, I have ran into a problem. In the following code you can assume that the player and the world are drawn in the function draw_world() and all of the variables I need to display are drawn in draw_debug(). Originally I had the debug values drawn before the world and I noticed that the world overlapped them so I made the debug values be drawn last. However, this still doesn't work. The variables don't stick to the 0, 0 that is in the top left of the window anymore, it is now drawn at 0, 0 in the world. I don't feel like a .love file is necessary for this issue so please don't ask me to provide one. I feel as though I have supplied all of the necessary code to understand the issue at hand.

Code: Select all

function love.draw()
    love.graphics.translate(-player.x + 400 - (player.w/2), -player.y + 300 - (player.h/2))
    draw_world()
    love.graphics.translate(0, 0)
    draw_debug()
end

[Joe Black]

the wiki say :

When this function is called with two numbers, dx, and dy, all the following drawing operations take effect as if their x and y coordinates were x+dx and y+dy.
This change lasts until love.draw() exits or else a love.graphics.pop reverts to a previous love.graphics.push.

so you must translate back like

Code: Select all

    
function love.draw()
   love.graphics.translate(-player.x + 400 - (player.w/2), -player.y + 300 - (player.h/2))
   draw_world()
   love.graphics.translate(-(-player.x + 400 - (player.w/2)),-( -player.y + 300 - (player.h/2)))
   draw_debug()
end

or more convenient if translate is not the only one transformation

Code: Select all

    
function love.draw()
   love.graphics.push()
   love.graphics.translate(-player.x + 400 - (player.w/2), -player.y + 300 - (player.h/2))
   draw_world()
   love.graphics.pop()
   draw_debug()
end

[Positive07]

Use [wiki]love.graphics.push[/wiki] and [wiki]love.graphics.pop[/wiki] to have a stack of all your transformations and move through them or alternatively use [wiki]love.graphics.origin[/wiki] to reset to the default

[kikito]

If you use my library, gamera, you will be able to do this:

Code: Select all

local gamera = require 'gamera'

local player, camera, world

function love.load()
  player = ...
  world = ...
  camera = gamera.new(0,0,world.width, world.height)
end

function love.update(dt)
  camera:setPosition(player.x, player.y)
  ...
end

function love.draw()
  -- you could also do cam:draw(draw_world)
  camera:draw(function()
    draw_world()
  end) 
  draw_debug()
end

[s-ol]

If you use my library, gamera, you will be able to do this:

Code: Select all

local gamera = require 'gamera'

local player, camera, world

function love.load()
  player = ...
  world = ...
  camera = gamera.new(0,0,world.width, world.height)
end

function love.update(dt)
  cam:setPosition(player.x, player.y)
  ...
end

function love.draw()
  -- you could also do cam:draw(draw_world)
  cam:draw(function()
    draw_world()
  end) 
  draw_debug()
end

Actually you could even DL

Code: Select all

cam:draw(draw_world)
draw_debug()

[kikito]

Yep, it's in the comment

[s-ol]

Yep, it's in the comment

whoops