converts an image into a header file with tile data

etc/rltile.lua

@@ -0,0 +1,69 @@
+local image = require 'image'
+local path = require 'path'
+
+local function rgbto16( r, g, b )
+  r = r * 31 // 255
+  g = g * 63 // 255
+  b = b * 31 // 255
+  
+  return ( r << 11 ) | ( g << 5 ) | b
+end
+
+return function( args )
+  if #args == 0 then
+    io.write[[
+Creates a .h header file with the tile ready to be used in tile functions
+rl_tile_blit_nobg, rl_tile_blit and rl_tile_unblit. The header file will have
+a pixel array with the same name as the input image with extension, and two
+macros with the tile's width and height will be defined.
+
+Ex. "luai rltile.lua grass.png" will create a grass.h file containing the
+grass_png pixel array and the grass_png_width and grass_png_height macros.
+
+Usage: luai rltile.lua <image>
+
+]]
+    
+    return 0
+  end
+  
+  local name   = path.realpath( args[ 1 ] )
+  local png    = image.load( name )
+  local width  = png:getWidth()
+  local height = png:getHeight()
+  local pixels = {}
+  
+  for y = 0, height - 1 do
+    for x = 0, width - 1 do
+      local c = rgbto16( image.split( png:getPixel( x, y ) ) )
+      pixels[ #pixels + 1 ] = c
+    end
+  end
+  
+  local dir, name, ext = path.split( name )
+  local file, err = io.open( dir .. path.separator .. name .. '.h', 'w' )
+  if not file then error( err ) end
+  
+  local array = string.gsub( name .. ext, '[%.\\/:]', '_' )
+  
+  file:write( 'const uint16_t ', array, '[] = {\n' )
+  
+  for i = 1, #pixels, 8 do
+    local line = {}
+    table.move( pixels, i, i + 7, 1, line )
+    file:write( '  ' )
+    
+    for j = 1, #line do
+      file:write( string.format( '0x%04x, ', line[ j ] ) )
+    end
+    
+    file:write( '\n' )
+  end
+  
+  file:write( '};\n\n' )
+  file:write( '#define ', array, '_width ', tostring( width ), '\n' )
+  file:write( '#define ', array, '_height ', tostring( height ), '\n' )
+  file:close()
+  
+  return 0
+end