add dedicated backend (WIP)

luigi/backend/ffisdl/spritebatch.lua

@@ -0,0 +1,75 @@
+local REL = (...):gsub('[^.]*$', '')
+
+local sdl = require(REL .. 'sdl')
+
+local SpriteBatch = setmetatable({}, { __call = function (self, ...)
+    local object = setmetatable({}, { __index = self })
+    return object, self.constructor(object, ...)
+end })
+
+--[[
+spriteBatch = SpriteBatch( image, size )
+
+Arguments
+
+Image image
+    The Image to use for the sprites.
+number size (1000)
+    The max number of sprites.
+
+Returns
+
+SpriteBatch spriteBatch
+    The new SpriteBatch.
+--]]
+function SpriteBatch:constructor (image)
+    self.image = image
+    self.sprites = {}
+end
+
+--[[
+id = SpriteBatch:add( quad, x, y, r, sx, sy )
+
+Arguments
+
+Quad quad
+    The Quad to add.
+number x
+    The position to draw the object (x-axis).
+number y
+    The position to draw the object (y-axis).
+number r (0)
+    Orientation (radians). (not implemented)
+number sx (1)
+    Scale factor (x-axis).
+number sy (sx)
+    Scale factor (y-axis).
+
+Returns
+
+number id
+    An identifier for the added sprite.
+--]]
+function SpriteBatch:add (quad, x, y, r, sx, sy)
+    local sprites = self.sprites
+
+    sprites[#sprites + 1] = { quad = quad, x = x, y = y,
+        sx = sx or 1, sy = sy or 1 }
+end
+
+function SpriteBatch:draw ()
+    local image = self.image
+    local renderer = image.sdlRenderer
+    local texture = image.sdlTexture
+
+    for _, sprite in ipairs(self.sprites) do
+        local quad = sprite.quad
+        local w = math.ceil(quad[3] * sprite.sx)
+        local h = math.ceil(quad[4] * sprite.sy)
+        local src = sdl.Rect(quad)
+        local dst = sdl.Rect(sprite.x, sprite.y, w, h)
+        sdl.renderCopy(renderer, texture, src, dst)
+    end
+end
+
+return SpriteBatch