problem loading texture with transparency with OpenGL ES and Android

问题

Im trying to load an image that has background transparency that will be layered over another texture. When i try and load it, all i get is a white screen. The texture is 512 by 512, and its saved in photoshop as a 24 bit PNG (standard PNG specs in the Photoshop Save for Web and Devices config window). Any idea why its not showing? The texture without transparency shows without a problem. Here is my loadTextures method:

public void loadGLTexture(GL10 gl, Context context) {
    //Get the texture from the Android resource directory
    Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.m1);
    Bitmap normalScheduleLines = BitmapFactory.decodeResource(context.getResources(), R.drawable.m1n);


    //Generate texture pointers...
    gl.glGenTextures(3, textures, 0);
    //...and bind it to our array
    gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[1]);
    //Create Nearest Filtered Texture
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_LINEAR_MIPMAP_NEAREST);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);
    gl.glTexParameterf(GL11.GL_TEXTURE_2D, GL11.GL_GENERATE_MIPMAP, GL11.GL_TRUE);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE);
    GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);

    bitmap.recycle();


    //Bind our normal schedule bus map lines
    gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]);
    //Create Nearest Filtered Texture
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_LINEAR_MIPMAP_NEAREST);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);
    gl.glTexParameterf(GL11.GL_TEXTURE_2D, GL11.GL_GENERATE_MIPMAP, GL11.GL_TRUE);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_CLAMP_TO_EDGE);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_CLAMP_TO_EDGE);
    GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, GL10.GL_RGBA, normalScheduleLines, 0);

    normalScheduleLines.recycle();

}

回答1:

It was actually the automatically generated mipmaps that was preventing the PNG from being displayed. I changed

    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_LINEAR_MIPMAP_NEAREST);

    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST);

and sure enough, it worked. Not sure why it doesn't like the PNG with alpha but when i do find out i will post here.

来源：https://stackoverflow.com/questions/4580195/problem-loading-texture-with-transparency-with-opengl-es-and-android

标签

iphone

android

opengl-es

transparency

textures