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Offline zparticle

Senior Duke




Thick As A Brick


« Posted 2004-01-20 13:17:58 »

Could someone please enlighten me on what the purpose of the following code from the TextureLoader class is:

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    private synchronized BufferedImage loadImageFast(String name, boolean expectAlpha) {
        try {

            String cacheName = null;
            if (cachePath != null) {
                File f = new File(name);
                cacheName = cachePath+f.getName() + ".img";

                f = new File(cacheName);
                if (f.exists()) {
                    FileInputStream fs = new FileInputStream(f);
                    FileChannel fc = fs.getChannel();
                    MappedByteBuffer bb = fc.map(FileChannel.MapMode.READ_ONLY,0,f.length());
                    boolean hasAlpha = (bb.getInt()==1) ? true : false;
                    int width = bb.getInt();
                    int height = bb.getInt();
                    DirectBufferedImage im = null;
                    if (hasAlpha) im = (DirectBufferedImage)DirectBufferedImage.getDirectImageRGBA(width,height);
                    else im = (DirectBufferedImage)DirectBufferedImage.getDirectImageRGB(width,height);
                    bb.get(im.getBackingStore());
                    return im;
                }
            }


I don't understand the purpose of the MappedByteBuffer and FileChannel objects. Why not simply read the width and height from the FileInputStream. and what is the point of the following line:

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                    bb.get(im.getBackingStore());

Offline xbrain

Senior Newbie




Java games are the Future


« Reply #1 - Posted 2004-01-21 10:36:24 »

Perhaps is it (again) a problem of low/high bit weight ?  Tongue

XBrain - Don't let others control your Mind...
Offline DavidYazel

Junior Duke




Java games rock!


« Reply #2 - Posted 2004-01-23 21:32:37 »

That feature is designed to sacrifice disk space for faster texture loading.  If it turned on then the first time the texture is read it is stored in uncompressed form on the disk.  The second time you run it maps the file into memory using NIO and just copies the data directly into the bytebuffer of the image, which is in turn passed directly to OpenGL

David Yazel
Xith3D Project Founder
http://xith3d.dev.java.net

It may look complicated, but in the end it is just a bunch of triangles
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