Android 在GLSURFACHEVIEW上加载两个纹理一个作为背景，一个作为带有alpha的前景

我已经建立了一个GLSURFACHEVIEW，并希望执行以下操作：

加载纹理作为背景使其全屏显示而不拉伸图像

用alpha加载另一个纹理，使其成为前景。因此背景图片是可见的，比如应用雾效果或雨效果。也可全屏显示，无需拉伸图像

任何关于如何正确加载纹理并将其设置在GLSURFACHEVIEW上的信息都将不胜感激

我尝试了以下代码在我的GLSURFACHEVIEW上加载纹理，但不适用于我：

import javax.microedition.khronos.opengles.GL10;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.opengl.GLUtils;

public class TextureHelper {
/**
 * Helper method to load a GL texture from a bitmap
 *
 * Note that the caller should "recycle" the bitmap
 *
 * @return the ID of the texture returned from glGenTextures()
 */
public static int loadGLTextureFromBitmap( Bitmap bitmap, GL10 gl ) {

    // Generate one texture pointer
    int[] textureIds = new int[1];
    gl.glGenTextures( 1, textureIds, 0 );

    // bind this texture
    gl.glBindTexture( GL10.GL_TEXTURE_2D, textureIds[0] );

    // Create Nearest Filtered Texture
    gl.glTexParameterf( GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_LINEAR );
    gl.glTexParameterf( GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR );

    gl.glTexParameterf( GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S, GL10.GL_REPEAT );
    gl.glTexParameterf( GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T, GL10.GL_REPEAT );

    // Use the Android GLUtils to specify a two-dimensional texture image from our bitmap
    GLUtils.texImage2D( GL10.GL_TEXTURE_2D, 0, bitmap, 0 );

    return textureIds[0];
}

/**
 * Create a texture from a given resource
 * 
 * @param resourceID the ID of the resource to be loaded
 * @param scaleToPO2 determines whether the image should be scaled up to the next highest power
 * of two, or whether it should be "inset" into such an image. Having textures that are
 * dimensions of some power-of-two is critical for performance in opengl.
 *
 * @return the ID of the texture returned from glGenTextures()
 */
public static int loadGLTextureFromResource( int resourceID, Context context, boolean scaleToPO2 , GL10 gl ) {

    // pull in the resource
    Bitmap bitmap = null;
    Resources resources = context.getResources();

    Drawable image = resources.getDrawable( resourceID );
    float density = resources.getDisplayMetrics().density;

    int originalWidth = (int)(image.getIntrinsicWidth() / density);
    int originalHeight = (int)(image.getIntrinsicHeight() / density);

    int powWidth = getNextHighestPO2( originalWidth );
    int powHeight = getNextHighestPO2( originalHeight );

    if ( scaleToPO2 ) {
        image.setBounds( 0, 0, powWidth, powHeight );
    } else {
        image.setBounds( 0, 0, originalWidth, originalHeight );
    }

    // Create an empty, mutable bitmap
    bitmap = Bitmap.createBitmap( powWidth, powHeight, Bitmap.Config.ARGB_4444 );
    // get a canvas to paint over the bitmap
    Canvas canvas = new Canvas( bitmap );
    bitmap.eraseColor(0);

    image.draw( canvas ); // draw the image onto our bitmap

    int textureId = loadGLTextureFromBitmap( bitmap , gl );

    bitmap.recycle();

    return textureId;
}

/**
 * Calculates the next highest power of two for a given integer.
 *
 * @param n the number
 * @return a power of two equal to or higher than n
 */
public static int getNextHighestPO2( int n ) {
    n -= 1;
    n = n | (n >> 1);
    n = n | (n >> 2);
    n = n | (n >> 4);
    n = n | (n >> 8);
    n = n | (n >> 16);
    n = n | (n >> 32);
    return n + 1;
}
}

这是“我的活动”中的onCreate代码：

    private GLSurfaceView mGLView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    GLES20Renderer.context = this;

    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
            WindowManager.LayoutParams.FLAG_FULLSCREEN);

    if (hasGLES20()) {
        mGLView = new GLSurfaceView(this);
        mGLView.setEGLContextClientVersion(2);
        mGLView.setPreserveEGLContextOnPause(true);
        mGLView.setRenderer(new GLES20Renderer());
    } else {
        mGLView = new GLSurfaceView(this);
        mGLView.setEGLContextClientVersion(1);
        mGLView.setPreserveEGLContextOnPause(true);
        mGLView.setRenderer(new GLES20Renderer());
    Log.i("S"," does not support open gl 2");
        // you gotta get a phone that supports Open GL 2.0
    }

    setContentView(mGLView);
}

这是GLSurfaceView.Renderer的代码：

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我想我可能在绘图部分漏掉了一些代码：我不知道如何使用alpha启用加载其他纹理…

如果我错了，很抱歉，但我想你是OpenGL的初学者。所以，我将尽力帮助你学习

首先，我建议您只使用OpenGLES 2.0，因为它受Android 2.2 API level 8及更高版本的支持。阅读如今，所有android版本都高于API 8级

要使用OpenGl ES 2.0绘制任何内容，必须使用GLES20.glDrawArrays。。或GLES20.GldrawerElements。。。阅读我没看到你被称为这些方法之一

回答你的问题：

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有很多方法可以控制一幅图像的alpha。最简单的方法是创建自己的片段着色器。阅读以了解创建着色器的基本步骤。

您还必须发布GlSurfaceView.Renderer.onSurfaceCreated的实现。。。onSurfaceChanged…完成，添加了实现。

    @Override
    public void onDrawFrame(boolean firstDraw) {
        int textureid = TextureHelper.loadGLTextureFromResource(R.drawable.ic_launcher, context, true, gl);
    }

    public void onSurfaceChanged(GL10 gl, int width, int height) {
    gl.glViewport(0, 0, width, height);
}

public void onSurfaceCreated(GL10 gl, EGLConfig config) {
    gl.glClearColor(0.0f, 0.4f, 0.4f, 1.0f);
}