Is there a way to adjust the width and height of a texture while not zeroing or overwriting its contents? I'd like to do this without a drawing cycle since for some operations a certain arrangement of W-H would be more suitable than others.
Is there a direct way? No.
You'd have to copy the contents to another texture, then resize the original, then copy it back.
But, if you're going to go to that trouble you might as well just make some texture class that when you resize makes a new texture, copies the old contents to the new texture and deletes the old texture.
Related
First of all, I would like to say that I'm fairly new to AS3, so feel free to correct me when needed.
So I'm trying to create a moving background, made out of different types of isometric tiles, like a floor or a wall, disposen in a grid like fashion.
At first, I tried creating a symbol containing the floor and the wall on different frames, and alternate between the frames as needed. Then I would add multiple instances of this symbol to a container and move the container around. Quickly I realized that this probably wouldn't be an ifficient method, as confirmed by the unsmooth movement of the container. (I gave up on this method).
So I did a little digging around, and then I converted the tile symbol to a png file, created a bitmap container to where I would copyPixels from the png as many times as the map required it.
The problem now is that when I do this:
var pngBitmapData:BitmapData=new tilePng
the bitmapData height and width don't match the height and width of the actual tile. There seem to be some transparent pixels around the tile and I have no idea how to remove them. This causes the tiles to be misaligned on the background's grid, with some small empty spaces around them.
So I have a couple of questions:
Is this an effective way to build the background?
Is there a way to avoid that transparent pixels "problem" ?
Hmm, it's hard to tell without seeing your png.
Are you doing this?
var pngBitmapData:BitmapData = new tilePng();
var bmp:Bitmap = new Bitmap(pngBitmapData);
To initialize your bitmap?
Also, check the anti-aliasing on your bitmap, that could be it. I'd set it to none.
I am drawing many audio meters on a view and finding that drawRect can not keep up with the speed of the audio change. In practice only a very small part of the image changes at a time so I really only want to draw the incremental changes.
I have created a CGLayer and when the data changes I use CGContextBeginPath, CGContextMoveToPoint, CGContextAddLineToPoint and CGContextStrokePath to draw in the CGLayer.
In drawRect in the view I use CGContextDrawLayerAtPoint to display the layer.
When the data changes I draw just the difference by drawing a line over the top in the CGLayer. I had assumed it was like photoshop and the new data just draws over the old but I now believe that all the lines I have ever drawn remain present in the layer. Is that correct?
If so is there a way to remove lines from a CGLayer?
What exactly do you mean by 'audio meter' show some snapshots of your intended designs. Shows us some code...
These are my suggestions-
1) Yes the new data just draws on top of CGLayer unless you release it CGLayerRelease(layer)
2) CGContextStrokePath is an expensive operation. You may want to create a generic line stroke and store them in UIImage. Then reuse the UIImage everytime your datachanges.
3) Simplest solution: use UIProgressView if you just want to show audio levels.
I now believe that all the lines I have ever drawn remain present in the layer. Is that correct?
Yes.
If so is there a way to remove lines from a CGLayer?
No. There is not. You would create a new layer. Generally, you create a layer for what is drawn repeatedly.
Your drawing may be able to be simplified by drawing rects rather than paths.
For some audio meters, dividing the meter into multiple pieces may help (you could use a CGLayer here). Similarly, you may be able to just draw rectangles selectively and/or clip drawing, images, and/or layers.
I have a texture which I use as a texture map. Its a 2048 by 2048 texture divided in squares of 256 pixels each. So I have 64 "slots". This map can be empty, partly filled or full. On screen I am drawing simple squares with a slot of the sprite map each.
The problem is that I have to update this map from time to time when the asset for the slot becomes available. These assets are being downloaded from the internet but the initial information arrives in advance so I can tell how many slots I will use and see the local storage to check which ones are already available to be drawn at the start.
For example. My info says there will be 10 squares, from these 5 are available locally so when the sprite map is initialized these squares are already filled and ready to be drawn. On the screen I will show 10 squares. 5 of them will have the image stored in the texture map for those slots, the remaining 5 are drawn with a temporal image. As a new asset for a slot is downloaded I want to update my sprite map (which is bound and used for drawing) with the new corresponding texture, after the draw is finished and the sprite map has been updated I set up a flag which tells OpenGL that it should start drawing with that slot instead of the temporal image.
From what I have read, there are 3 ways to update a sprite map.
1) Upload a new one with glTextImage2D: I am currently using this approach. I will create another updater texture and then simply swap it. But i frequently run into memory warnings.
2) Modify the texture with glTextSubImage2D: I cant get this to work, I keep getting memory access errors or black textures. I believe its either because the thread is not the same or I am accessing a texture in use.
3) Use Frame Buffer Objects: I could try this but I am not certain if i can Draw on my texturebuffer while it is already being used.
What is the correct way of solving this?
This is meant to be used on an iPhone so resources are limited.
Edit: I found this post which talks about something related here.
Unfortunately I dont think its focused on modifying a texture that is currently being used.
the thread is not the same
OpenGL-ES API is absolutely not multi-threaded. Update your texture from main thread.
Because your texture must be uploaded on gpu, glTextSubImage2D is the fastest and simplest path. Keep this direction :)
Render on a Frame Buffer (attached on your texture) is very fast for rendering data which are already on gpu. (not your case). And yes you can draw on a frame buffer bound to a texture (= a frame buffer which use the texture as color attachment).
Just one contrain: You can't read and write the same texture in one draw call (The texture attached to the current frame buffer can't be bound to a texture unit)
Morning all (if its morning where you are)
I have been looking around and have not seen a satisfactory method for doing this so thought I would ask around...
Ideal world I would like to be able to generate a transparent Texture2D object. Drawing this to the screen I would like to be able to "paint" to it, i.e. when the left mouse button is down whatever pixel the cursor is over should be set to black. Following this I would then need to be able to use this texture.
Using the texture is the easy part, we can simply make a new Texture2D attribute for a "painting" object and use that in the SpriteBatch.Draw method. The two tricky parts are
Generating a texture2D object of a specified size, filled with transparency in code.
Editing that texture2D on the fly (i.e. being able to alter pixel colours)
If anyone has any experience of these you input would be very much appreciated.
You can either use a RenderTarget2D (MSDN), which is itself a Texture2D (so you can use it in SpriteBatch.Draw). This allows you to render onto a texture in the same way you render onto the screen. You need to use GraphicsDevice.SetRenderTarget (MSDN) to set this up.
Or you can use Texture2D.SetData (MSDN) to manipulate pixels directly. You can construct a transparent Texture2D directly (MSDN). Don't forget to Dispose of any textures or other resources you create yourself!
If I have a texture file how would I be able to load up only a part of it using a defined rect (top, left, bottom, right)?
Is it technically possibly to only read in the parts I want to load while leaving the rest of the texture untouched?
What exactly are you trying to achieve. Its pretty simple to load up only a small part of a file into a single texture that encompasses it all. You'll probably need to write your own image parser, though.
If you want to load a partial image into a texture thats the same size as the original image (ie only update the area you are after) then this is relaitvely simple as well. You can LockRcts with a rect that is the area you want you update. You'll still need to write your own image parser though.
Personally in situations like this I prefer to use my own texture format that is already in the format I'm after ...
Look at D3DXCreateTextureFromFileEx: http://msdn.microsoft.com/en-us/library/bb172802%28v=VS.85%29.aspx
Otherwise, load the portion of the data you require yourself into memory, create an empty texture and lock it and copy the data.