android - 压缩纹理在 Android 中变为白色

Question

我是 android 和 OpenGL 开发的新手我尝试只做一个带有纹理的立方体，但我需要在 ETC1 压缩中压缩这个纹理，我制作了一个代码，就像我在 develop.android 网站上找到的一样，但代码只在模拟器上运行!

我在两个设备上测试

1) Nexus mobile，在这个设备中没有出现立方体，我在网上搜索，我发现这个设备原来的Android是2.1，升级到2.3，这是使设备可以绘图的原因幼崽？

2) Motorola Xoom Tablet, Android 3.1 Device, 这里出现立方体但是颜色是白色, 不是Uncompressed texture, 支持CTE1, 没有OPENGL Error !

压缩后的贴图是PNG 265 * 265/，我把压缩后的贴图放在raw文件夹里

代码如下

public class TextureCube {
private String TAG;
private Context context;
private FloatBuffer vertexBuffer; // Buffer for vertex-array
private FloatBuffer texBuffer; // Buffer for texture-coords-array

private float[] vertices = { // Vertices for a face
-1.0f, -1.0f, 0.0f, // 0. left-bottom-front
        1.0f, -1.0f, 0.0f, // 1. right-bottom-front
        -1.0f, 1.0f, 0.0f, // 2. left-top-front
        1.0f, 1.0f, 0.0f // 3. right-top-front
};
float[] texCoords = { // Texture coords for the above face
0.0f, 1.0f, // A. left-bottom
        1.0f, 1.0f, // B. right-bottom
        0.0f, 0.0f, // C. left-top
        1.0f, 0.0f // D. right-top
};
int[] textureIDs = new int[1]; // Array for 1 texture-ID

// Constructor - Set up the buffers
public TextureCube(Context context) {
    this.context = context;
    TAG = "Sam Messages: " + this.getClass().getName();
    // Setup vertex-array buffer. Vertices in float. An float has 4 bytes
    ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length * 4);
    vbb.order(ByteOrder.nativeOrder()); // Use native byte order
    vertexBuffer = vbb.asFloatBuffer(); // Convert from byte to float
    vertexBuffer.put(vertices); // Copy data into buffer
    vertexBuffer.position(0); // Rewind

    // Setup texture-coords-array buffer, in float. An float has 4 bytes
    ByteBuffer tbb = ByteBuffer.allocateDirect(texCoords.length * 4);
    tbb.order(ByteOrder.nativeOrder());
    texBuffer = tbb.asFloatBuffer();
    texBuffer.put(texCoords);
    texBuffer.position(0);
}

// Draw the shape
public void draw(GL10 gl) {


    gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
    gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);

    gl.glFrontFace(GL10.GL_CCW); // Front face in counter-clockwise orientation
    gl.glEnable(GL10.GL_CULL_FACE); // Enable cull face
    gl.glCullFace(GL10.GL_BACK); // Cull the back face (don't display)

    gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
    gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
    gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY); // Enable texture-coords-array
    gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, texBuffer); // Define texture-coords buffer

    // front
    gl.glPushMatrix();
    gl.glTranslatef(0.0f, 0.0f, 1.0f);
    gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
    gl.glPopMatrix();

    // left
    gl.glPushMatrix();
    gl.glRotatef(270.0f, 0.0f, 1.0f, 0.0f);
    gl.glTranslatef(0.0f, 0.0f, 1.0f);
    gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
    gl.glPopMatrix();

    // back
    gl.glPushMatrix();
    gl.glRotatef(180.0f, 0.0f, 1.0f, 0.0f);
    gl.glTranslatef(0.0f, 0.0f, 1.0f);
    gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
    gl.glPopMatrix();

    // right
    gl.glPushMatrix();
    gl.glRotatef(90.0f, 0.0f, 1.0f, 0.0f);
    gl.glTranslatef(0.0f, 0.0f, 1.0f);
    gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
    gl.glPopMatrix();

    // top
    gl.glPushMatrix();
    gl.glRotatef(270.0f, 1.0f, 0.0f, 0.0f);
    gl.glTranslatef(0.0f, 0.0f, 1.0f);
    gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
    gl.glPopMatrix();

    // bottom
    gl.glPushMatrix();
    gl.glRotatef(90.0f, 1.0f, 0.0f, 0.0f);
    gl.glTranslatef(0.0f, 0.0f, 1.0f);
    gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
    gl.glPopMatrix();

    gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);   // Disable
                                                            // texture-coords-array
    gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
    gl.glDisable(GL10.GL_CULL_FACE);
}

// Load an image into GL texture
public void loadTexture(GL10 gl) {

    Boolean loadCompressed = true;
    if (loadCompressed) {
        /****************************************************/
        /** LOAD A COMPRESSED TEXTURE IMAGE */
        /***********************************/
        Log.w(TAG, ": ETC1 texture support: " + ETC1Util.isETC1Supported());
        try {
              ETC1Util.loadTexture(GLES20 .GL_TEXTURE_2D, 0, 0,
                      GLES20.GL_RGB, GLES20.GL_UNSIGNED_SHORT_5_6_5,
                      context.getResources().openRawResource(R.raw.pic3));

            Log.w(TAG, ": OpenGL Error -After LoadTexture()-:" + gl.glGetError());
            Log.w(TAG,"OpenGL Extensions: " + gl.glGetString(GL10.GL_EXTENSIONS));
        } catch (IOException e) {
            Log.w(TAG, ": Could not load texture: " + e);
        } finally {

                Log.w(TAG, ": OpenGL Error -In Final()-:" + gl.glGetError());
        }
    } else {
        /*****************************************************/
        /** LOAD A TEXTURE IMAGE */
        /************************/

        gl.glGenTextures(1, textureIDs, 0); // Generate texture-ID array
        gl.glBindTexture(GL10.GL_TEXTURE_2D, textureIDs[0]); // Bind to texture ID Set up texture filters
        gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER,GL10.GL_NEAREST);
        gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER,GL10.GL_LINEAR);
        InputStream istream = context.getResources().openRawResource(R.drawable.pic5);
        Bitmap bitmap;
        try {
            bitmap = BitmapFactory.decodeStream(istream);
        } finally {
            try {
                istream.close();
            } catch (IOException e) {
            }
        }
        // Build Texture from loaded bitmap for the currently-bind texture
        // ID
        GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);
        bitmap.recycle();
        /******************************************************/
    }
}

Answer 1

您未能为压缩纹理加载设置纹理名称，这两个函数调用

gl.glGenTextures(1, textureIDs, 0); // Generate texture-ID array
gl.glBindTexture(GL10.GL_TEXTURE_2D, textureIDs[0]); // Bind to texture

这样做，所以将它们放在函数的开头。

“白色”纹理通常表示纹理不完整。如果您启用了 mipmap 但没有提供所有必需的 mipmap 级别，通常会发生这种情况。在上面的代码中，您禁用了未压缩纹理的 mipmaping:

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

但为了压缩，请保持原样——尝试将这两个调用放在名称生成之后，即 if(compressed) 之前，会发生什么情况:

public void loadTexture(GL10 gl) {

    gl.glGenTextures(1, textureIDs, 0);
    gl.glBindTexture(GL10.GL_TEXTURE_2D, textureIDs[0]);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER,GL10.GL_NEAREST);
    gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER,GL10.GL_LINEAR);

    Boolean loadCompressed = true;
    if (loadCompressed) {
        /****************************************************/
        /** LOAD A COMPRESSED TEXTURE IMAGE */
        /***********************************/
        Log.w(TAG, ": ETC1 texture support: " + ETC1Util.isETC1Supported());
        try {
              ETC1Util.loadTexture(GLES20 .GL_TEXTURE_2D, 0, 0,
                      GLES20.GL_RGB, GLES20.GL_UNSIGNED_SHORT_5_6_5,
                      context.getResources().openRawResource(R.raw.pic3));

            Log.w(TAG, ": OpenGL Error -After LoadTexture()-:" + gl.glGetError());
            Log.w(TAG,"OpenGL Extensions: " + gl.glGetString(GL10.GL_EXTENSIONS));
        } catch (IOException e) {
            Log.w(TAG, ": Could not load texture: " + e);
        } finally {

                Log.w(TAG, ": OpenGL Error -In Final()-:" + gl.glGetError());
        }
    } else {
        /*****************************************************/
        /** LOAD A TEXTURE IMAGE */
        /************************/
        InputStream istream = context.getResources().openRawResource(R.drawable.pic5);
        Bitmap bitmap;
        try {
            bitmap = BitmapFactory.decodeStream(istream);
        } finally {
            try {
                istream.close();
            } catch (IOException e) {
            }
        }
        // Build Texture from loaded bitmap for the currently-bind texture
        // ID
        GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);
        bitmap.recycle();
        /******************************************************/
    }
}