OpenGL, how to load non power of two dimension bitmap?

guian · by **guian** » Thu Dec 04, 2008 5:51 pm

in the OpenGL android API
(android.opengl.GLUtils.texImage2D() )
( http://code.google.com/android/referenc ... Utils.html )

we can read=>
"Whether or not bitmap can have non power of two dimensions depends
on the current OpenGL context."

I load my OpenGL context using :
mEglContext = mEgl.eglCreateContext(mEglDisplay,
mEglConfig,EGL10.EGL_NO_CONTEXT, null);
do you know what do I have to do in order to load non power of two
dimensions bitmap?

guian · by **guian** » Fri Dec 05, 2008 12:01 pm

the answer :

its NOT possible to load non power of two size bitmap as texture

but it's very easy to resize our bitmap

=>

Syntax: [ Download ] [ Hide ]

Using java Syntax Highlighting

 
        //correct the bitmap if its not a power of two width 
 
        if(((Math.log((double)bitmap.getWidth())/Math.log(2.0)) 
 
                        - Math.floor((Math.log((double)bitmap.getWidth())/Math.log(2.0)))) != 0){
 
                //the bitmap width isn't a power of two.
 
                int aimWidth = (int) Math.pow(2,Math.ceil(Math.log((double)bitmap.getWidth())/Math.log(2.0)));
 
                bitmap = Bitmap.createScaledBitmap(bitmap, aimWidth, bitmap.getHeight(), false);
 
               //you can adapt the height in the same way if needed.
 
        }
 
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MrSnowflake · by **MrSnowflake** » Fri Dec 05, 2008 12:45 pm

guian wrote:but it's very easy to resize our bitmap

Simple yes (if you have the code, as we do now), but very expensive! (I suppose) The Log will probably use a lot of cycles, so make sure, you resize your bitmaps in advance!

Emmanuel7 · by **Emmanuel7** » Fri Dec 12, 2008 2:34 am

Note :
A much more lighter way to know whether a number is a power of 2 is to test for :
x & ( x-1 ) == 0

OpenGL, how to load non power of two dimension bitmap?

OpenGL, how to load non power of two dimension bitmap?

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