Is it possible to change a Bitmap's image "on the fly"

techdojo · August 2012

EDIT : YES IT IS! (see Bitmap:setTexture() and Bitmap:setTextureRegion() in 2012.8.2+)

I'm working on a super fast text renderer for which I want to use a single texture atlas containing all the font images that I want to use.

The idea is to have a number of "rows" that can contain text strings of different lengths, over time the contents of these row's will be updated and the text will change - currently whenever a row is updated, I create a new Sprite for the row and then add in a series of new Bitmaps (1 per character), however when there are multiple updates you get nasty spikes in the framerate - which I've tracked down to the amount of garbage being generated for all the above memory allocations.

A much better solution would be to "pre-allocate" a bank of bitmaps for each row (for the max number of possible characters per row contents), set them all to be invisible and then instead of re-creating each Bitmap, just simply change the U,V,Width/Height info for each bitmap effectively making it "point" to a different character in the font texture and then making it visible.

But...

The $64,000 question, is.. is it possible to update the texture region that a bitmap points to without having to create a new one. I'm sure it can be with a Shape using the beginPath, moveTo and lineTo functions but that seems overkill and might even be slower than the Bitmap.new()

I initially considered the TileMap:setTile() function but that would only work with a fixed with font.

Anyone (yeah I'm looking you @Atilim - master of the undocumented functions

) know of a way it can be done on Bitmaps?

As a side note - it'll make bitmap animations an absolute breeze!

PS. If it's NOT possible then prepare to expect a horde of very loud mice *squeaking* this way soon!

techdojo · September 2012

Bump?

atilim · September 2012

It's great (and easy to implement) idea and therefore I've already added these functions:

Bitmap:setTexture(Texture or TextureRegion)
TextureRegion:setRegion(x, y, width, height)
TextureRegion:getRegion() -- returns x, y, width, height

Also I've started to think about Meshes.

techdojo · September 2012

@Atilm you ARE a star (and I don't mean in the flaming big ball of gas, prone to violent eruptions sense)

Thank you very much ^:)^

Nascode · September 2012

one *squeak* down

Thank you @atilim

OZApps · September 2012

It's great (and easy to implement) idea and therefore I've already added these functions:
Bitmap:setTexture(Texture or TextureRegion)
TextureRegion:setRegion(x, y, width, height)
TextureRegion:getRegion() -- returns x, y, width, height
Also I've started to think about Meshes.

So I guess that can also be used for Animations from spritesheets, right?

So, do you mean we could use something like

local tex = Texture.new("someimage.png")
local bmp = Bitmap.new(TextureRegion.new(x,y,wd,ht))

and then somewhere in the code

bmp:getTexture():setTextureRegion(x1,y1,wd1,ht1)

or maybe

bmp:setTextureRegion(x1,y1,wd1,ht1)

techdojo · September 2012

That's exactly what it could be used for.

If developers embrace this and put all their anims on a single frame it'll make a really big difference to the app running speed - ESPECIALLY if you reuse objects and don't create any new objects in your EnterFrame function

It'll also be a LOT more efficient than using Movieclips for big anims as you won't have to have a single sprite for each frame - just ONE bitmap that you just change the texture on.

atilim · September 2012

@OZApps exactly. But with one difference, there won't be Bitmap:getTexture() function. You should hold a reference to your TextureRegion somewhere else like:

local texture = Texture.new("someimage.png")
local textureRegion = TextureRegion.new(texture, x, y, width, height)
local bitmap = Bitmap.new(textureRegion)
 
-- and then somewhere in the code
 
textureRegion:setRegion(x1, y1, width1, height1)
bitmap:setTexture(textureRegion) -- you should also set texture region so that bitmap gets the parameters

GregBUG · September 2012

wow... i'm just coding Animator Studio 1.5

OZApps · September 2012

@Atilim, and this will be in the coming release, right? I was so excited that I wrote some code to create and handle some animation based on that and when I ran it to test it...

Waiting for 2012.8.2

MikeHart · September 2012

@techdojo: What is the difference in text output between your solution and using BMFont? It uses only one texture map too.

techdojo · September 2012

The problem with BMFont is that if you want to change the text then a new set of bitmaps will be required (hence memory allocation, garbage collection etc), this solution will allow you to update text every frame without any of that overhead.

Scouser · September 2012

@techdojo: unless you use my modification to BMFont which allows the font to be a texture region of a larger texture so you could have multiple fonts on the same texture page. I already used this feature in HappyCatz

techdojo · September 2012

The issue isn't with packing all the images into a single atlas - this is already supported, the issue is being able to change a bitmap's image without having to create a new one and incur all the penalties associated with dynamic memory allocation.

Mells · September 2012

@atilim Great that you added this

Also I've started to think about Meshes.

From that discussion right?

atilim · September 2012

From that discussion right?

yes.

btw, previously I was planning to add only Bitmap:setTexture() function that accepts both Texture and TextureRegion objects but now there are two functions Bitmap:setTexture() and Bitmap:setTextureRegion() for setting Texture and TextureRegion objects separately.

techdojo · September 2012

Woo hoo

+1 for the squeakers

Mells · September 2012

For reference and people that will find this discussion :
Bitmap:setTexture() and Bitmap:setTextureRegion() are now documented [ link ].

Bitmap:setTexture(texture)

Sets the texture.
Parameters:
texture: (TextureBase)

Bitmap:setTextureRegion(textureRegion)

Sets the texture region.
Parameters:
textureRegion: (TextureRegion)

alexzheng · February 2013

So This modification will make the Button Class a little more efficient?

Button = Core.class(Bitmap)

function Button:updateVisualState(state)
if state then
self:setTexture(self.downState) ---here self.downState is now a Texture
else
self:setTexture(self.upState)
end
end

ar2rsawseen · February 2013

@alexzheng yes it should, basically as efficient as it can get

Howdy, Stranger!

Categories

In this Discussion

Top Posters

Is it possible to change a Bitmap's image "on the fly"

Comments

Bitmap:setTexture(texture)

Bitmap:setTextureRegion(textureRegion)

Howdy, Stranger!

Quick Links

Categories

In this Discussion

Top Posters

Is it possible to change a Bitmap's image "on the fly"

Comments

Bitmap:setTexture(texture)

Bitmap:setTextureRegion(textureRegion)