[Resolved] Bitmap Filtering(Simple 2x)

[Baskinein]

Hello all. I have come to a crossroad. I am working on a script right now that will take a bitmap and enlarge it to be twice as big. I'm just doing a simple 2x method. This is the basics of it...

for every x and y coordinate(so one pixel) the new bitmap will represent that as four pixels(2x2). The four coordinates are (2x,2y), (2x+1,2y), (2x,2y+1), (2x+1,2y+1).
My problem is that it takes too long to compute a large bitmap and I'm trying to figure out a way that is efficient to filter the bitmap like this while not lagging the game to death. The main problem is that I am doing this constantly(every Graphics update). If anyone has any ideas please let me know. I'll post anything I come up with in case anyone else tries to do this.

 

[arev]

Why don't you use Sprite.zoom_x = 2 (same for y)?

 

[linkz0r]

Why not...

# Original Bitmap
original = RPG::Cache.battler("001-Battler01", 0)

# Resized bitmap (needs to create before stretching duh xD)
resized = Bitmap.new(original.width*2, original.height*2)

# Some preparation...
src_rect = Rect.new(0, 0, original.width, original.height)
dest_rect = Rect.new(0, 0, resized.width, resized.height)
opacity = 255 # You can even define the opacity

# Zooming!
resized.stretch_blt(src_rect, original, dest_rect, opacity)

Or, you can use the Sprite#zoom_x and Sprite#zoom_y with the same value (in this case 2), and it´s a better option if you can take it. Any operation with Bitmaps' bits are laggy, and even more with loops.

 

[Baskinein]

Good thinking. I came up with a bunch of ideas to help speed up things, but the method stretch_blt is much faster than all of my ideas combined. Thanks a bunch for the idea of using stretch_blt. I'm not sure why, but I never considered that to be an option.

 

[SephirothSpawn]

Just so you know, I have also created a method that scales an image into a strecth regions and centers it. This prevents distortion.

class Bitmap
  def scale_blt(dest_rect, src_bitmap, 
      src_rect = Rect.new(0, 0, src_bitmap.width, src_bitmap.height), opacity = 255)
    w, h = src_rect.width, src_rect.height
    scale = [w / dest_rect.width.to_f, h / dest_rect.height.to_f].max
    ow, oh = (w / scale).to_i, (h / scale).to_i
    ox, oy = (dest_rect.width - ow) / 2, (dest_rect.height - oh) / 2
    stretch_blt(Rect.new(ox + dest_rect.x, oy + dest_rect.y, ow, oh), 
      src_bitmap, src_rect )
  end
end

You use it the same way you would the stretch_blt, just use scale_blt instead.

This topic has been resolved. If Baskinein or any other users have any questions or further problems regarding this topic, please create a new thread about them.

Thank you!