如何在android opengl es 2.0中解压纹理

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.opengl.GLES20;
import android.opengl.GLUtils;
import android.opengl.ETC1Util;
import android.opengl.ETC1Util.ETC1Texture;
import android.opengl.Matrix;

import java.io.IOException;
import java.io.InputStream;

public class TextureHelper {
    public static int loadTexture(Context context, int resourceId) {
        final int[] textureHandle = new int[1];

        GLES20.glGenTextures(1, textureHandle, 0);

        if (textureHandle[0] != 0) {
            BitmapFactory.Options options = new BitmapFactory.Options();
            options.inScaled = false;   // No pre-scaling

            // Read in the resource
            final Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), resourceId, options);

            // Bind to the texture in OpenGL
            GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureHandle[0]);

            // Set filtering
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_NEAREST);

            // Load the bitmap into the bound texture.
            GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);

            // Clean up
            bitmap.recycle();
        }

        if (textureHandle[0] == 0) {
            throw new RuntimeException("Error loading texture.");
        }

        return textureHandle[0];
    }

    public static int loadETC1Texture(Context context, String fileName) {
        final int[] textureHandle = new int[1];

        GLES20.glGenTextures(1, textureHandle, 0);

        if (textureHandle[0] != 0) {
            try {
                InputStream inputStream = context.getAssets().open(fileName);
                ETC1Texture etc1Texture = ETC1Util.createTexture(inputStream);
                GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureHandle[0]);
                ETC1Util.loadTexture(GLES20.GL_TEXTURE_2D, 0, 0, GLES20.GL_RGB, GLES20.GL_UNSIGNED_BYTE, etc1Texture);
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        if (textureHandle[0] == 0) {
            throw new RuntimeException("Error loading texture.");
        }

        return textureHandle[0];
    }
}