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.
Related
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.
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 have some images and I want to draw them using drawAtPoint ( I am using a table of 100s of cells and doing the draw as recommended for making the scrolling faster). Now, these images are kind of random (their size can be anything.. ) and I need to specify the dimension I want to fit in.
Can anyone kindly tell me what to do ?
Thanks.
Assuming I understand what you want to do use:
- (void)drawInRect:(CGRect)rect;
See http://developer.apple.com/library/ios/#documentation/uikit/reference/UIImage_Class/Reference/Reference.html
When using drawAtPoint you cannot specify the dimensions, it will draw the entire image in the current graphics context.
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!
I have two images that I want to display on top of each other. one image a single channel image and the second image is a RGB image but with most of the area being transparent.
How these two images are generated in different functions. I know to just display these on top of each other, i can use the same window name when calling cvShowImage() but this doesn't work when they are drawn from different functions. When trying this, I used cvCvtcolor() to convert he binary image from single channel to RGB and then displaying the second image from another function. But this didn't work. Both images are same dimension, depth and number of channels (after conversion).
I want to avoid passing in one image into the second function and then draw them. So I'm looking for a quick dirty trick to display these two images overlapped.
Thank you
EDIT:
I don't think that's possible. You'll have to create a new image or modify an existing one. Here's an article that shows how to do this: Transparent image overlays in OpenCV
There is no way to "overlay" images. cvShowImage() displays a single image from memory. You'll need to blend/combine them together. There are several ways to do this.
You can copy one into 1 or 2 channels of the other, you can use logical operations like AND, OR or XOR, you can use arithmetic operations like Add, Multiply and MultiplyScale (these operations will saturate values larger than 255). All these can also be done with an optional mask image like your blob image.
Naturally, you may want to do this into a third buffer so as not to overwrite your originals.
Apparently now it can be done using OpenCV 2.1 version
http://opencv.willowgarage.com/documentation/cpp/highgui_qt_new_functions.html#cv-displayoverlay