Android OpenGL ES 2.0纹理无法在某些尺寸下使用

Question

I just discovered a really bizarre problem with my app.

This problem occurs when it is run on my phone.

I was loading a bitmap (to be used as an Open GL Texture) like so:

 tiles = BitmapFactory.decodeResource(view.getResources(), R.drawable.tilespic, BMFOptions);

BMFOptions is setting the following line:

BMFOptions.inPreferredConfig = Bitmap.Config.RGB_565;

When I ran my app, what happened initially was that the texture appeared as just a black square. So, I tried it on another device (a tablet) and it ran perfectly.

I know that if the bitmap has an alpha channel, BitmapFactory will just load it as ARGB_8888 if Bitmap.Config.RGB_565 has been specified and I have confirmed this with other bitmaps (by calling getConfig). This bitmap does have Alpha.

However, when I call getConfig on it, it returns null (only when RGB_565 is specified and only on this one bitmap/texture - on this device).

What I've tried

If I set it to ARGB_8888 or just omit BMFOptions for this bitmap, then everything displays correctly.

If I set it to ARGB_4444 (just for testing), then it does display but the textures are crooked/at an angle, (again just this bitmap/texture).

So, what I did was resize the original bitmap (original size - 100 x 909).

I resized it to 505 x 201, 506 x 201 and a multitude of other sizes and it still didn't work (Note these are sprite sheets so, these sizes are just how to they worked out).

I then resized it to 506 x 204 and it did work. I then tried it at 1880 x 921 and it worked again.

I'm not using NPOT textures and have never had a problem before, bear in mind that I also have other textures with odd sizes such as 1880 x 921 and 1000 x 885 and these behave perfectly on this phone (but obviously their pixel data / layout is different).

As this bitmap has alpha (which I need), I am simply removing the BMFOptions for this particular bitmap for now and allowing it to load as ARGB_8888, however, I would like to know any possible reasons for this odd behaviour.

If it helps, this is the code I use to load my textures....

    public static int LoadTexture(GLSurfaceView view, Bitmap imgTex){

        int textures[] = new int[1];
        try {

            GLES20.glGenTextures(1, textures, 0);
            GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textures[0]);
            GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
            GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);

            GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, imgTex, 0);

            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T,GLES20.GL_CLAMP_TO_EDGE);
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S,GLES20.GL_CLAMP_TO_EDGE);

        } catch (Exception e){
          }
        textureCount++;     
        return textures[0];
    }

Answer 1

Some phones can only use textures with power of 2 sizes.
eg 256x256, 512x512, 1024x128 will work
300x300, 512x100, etc. won't work.

This is a requirement of the OpenGL ES 2.0 standard (afaik 3.0 relaxes this). Some phones will work with non-pow-of-2 textures, but it's not mandatory to do so. Sticking to pow-of-2 textures is the safe way to go if you wish to target as much phones as possible.

If this is not the problem, see if you get any GLErrors .

Also i just noticed: you are using GL10.GL_TEXTURE_2D, while in the other lines you are using GLES20.*. I looked it up and GL_TEXTURE_2D is defined as 3553 in both places, but still it would look better if you used GLES20 there as well.