Loading Textures fast into OpenGL 2.0

Question

I am building a simple live wallpaper for Android. I am uploading the required texture into OpenGL ES 2.0 using the below code. I have loaded all my images into a single file of size 2048x2048. This below code takes about 900 to 1200 ms to load the texture. Is this a normal time or am I doing something wrong to make it slow?

I also try to clear the list of textures in Opengl every time the onSurfaceCreated is called in my renderer. Is this right to be done, or is there a way to simple check if the previously loaded texture is already in memory and if so avoid clearing and reloading? Please let me know your comments on this. Thank you.

Also on screen orientation change the OnSurfaceCreated is called. So the texture upload happens again. This is not a good idea. What is the work around?

public int addTexture(Bitmap texture) {

    int bitmapFormat = texture.getConfig() == Config.ARGB_8888 ? GLES20.GL_RGBA : GLES20.GL_RGB;

    int[] textures = new int[1];
    GLES20.glGenTextures(1, textures, 0);
    int textureId = textures[0];
    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);

    GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmapFormat, texture, 0);
    GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR_MIPMAP_LINEAR);
    GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
    GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_REPEAT);
    GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_REPEAT);
    GLES20.glGenerateMipmap(GLES20.GL_TEXTURE_2D);
    return textureId;
}

Alexis Andre Alexis Andre · Accepted Answer · 2011-12-13T05:23:50

A few ways you can improve performance.

Do not load the texture every time onSurfaceChanged is called. Initialize your textureId to -1 (in the constructor/surfaceCreated of your renderer) and check at the beginning of onSurfaceChanged if you have a different Id. When you call glGenTextures, you will get a positive number.
Do you need the Mipmaps? That might be the key point of your method here. Try without the line GLES20.glGenerateMipMap(GLES20.GL_TEXTURE_2D);
2048x2048 is huge. Especially for textures. Do you really need that much detail? Maybe 1024x1024 is enough.
Avoid RGB_888, use RGB_565 instead: you'll get almost the same visual quality for half the size.

Loading Textures fast into OpenGL 2.0

1 Answers