Android：OpenGL ES 2.0 - 纹理始终为黑色

我试图使用顶点和片段着色器在 OpenGL ES 2.0（Android 4.0.4，Galaxy Nexus）中显示一个简单的纹理作为全屏背景。最终结果应该是在那里显示相机图像，但首先，文件中的简单纹理就足够了。我测试了很多东西，并且在我使用 OpenGL ES 1.x 时它工作了一段时间，但由于我计划使用着色器进行 YUV->RGB 转换，所以我必须使用 2.0。

我有以下顶点着色器：

attribute vec4 position;
attribute vec4 inputTextureCoordinate;

varying vec2 textureCoordinate;

void main() {
    gl_Position = position;
    textureCoordinate = inputTextureCoordinate.xy
}

和这个片段着色器：

varying highp vec2 textureCoordinate;

uniform sampler2D videoFrame;

void main() {
    gl_FragColor = texture2D(videoFrame, textureCoordinate);
}

像这样的着色器创建应该没问题，因为当我写的时候gl_FragColor=vec4(1,0,0,0)它工作得很好，并向我显示了红色背景。

OnSurfaceCreated我执行以下操作：

 a = makeFloatBuffer(squareVertices);
 b = makeFloatBuffer(textureVertices);

with squareVertices and textureVertices如下：

static float squareVertices[] = { -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f,
        1.0f, 1.0f, };

static float textureVertices[] = { 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f,
        0.0f, 0.0f, };

OnSurfaceChanged我执行以下操作：

GLES20.glViewport(0, 0, width, height);
Bitmap bitmap = BitmapFactory.decodeResource(mContext.getResources(), R.raw.htc);
GLES20.glGenTextures(1, textures, 0);
GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);

R.raw.htc 是 128x128 像素 png。

And OnDrawFrame:

    GLES20.glUseProgram(program);

    GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textures[0]);

    GLES20.glUniform1i(GLES20.glGetUniformLocation(program, "videoFrame"),0);

    GLES20.glClearColor(0.0f, 0.0f, 1.0f, 0.0f);
    GLES20.glClearDepthf(1.0f);
    GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);

    int x = GLES20.glGetAttribLocation(program, "position");
    int y = GLES20.glGetAttribLocation(program, "inputTextureCoordinate");

    GLES20.glEnableVertexAttribArray(x);        
    GLES20.glVertexAttribPointer(x, 2, GLES20.GL_FLOAT, false, 0, a);
    GLES20.glEnableVertexAttribArray(y);
    GLES20.glVertexAttribPointer(y, 4, GLES20.GL_FLOAT, false, 0, b);

    GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

我唯一看到的是全黑的屏幕，我不知道为什么。我在这里看到了其他一些有类似问题的帖子，但所提出的解决方案都没有帮助我，或者根本没有给出解决方案。

如上所述，我们可以找到该问题的解决方案，尽管我们不知道它现在起作用而以前不起作用的确切原因（我们改变了几件事，突然它起作用了）。尽管如此，我想分享我们的工作版本：

着色器现已完成，还可以进行 YUV->RGB 转换： 顶点着色器：

attribute vec4 position;
attribute vec4 inputTextureCoordinate;

varying vec2 textureCoordinate;

 void main() {
      gl_Position = position;
      textureCoordinate = inputTextureCoordinate.xy;
 };

片段着色器：

varying highp vec2 textureCoordinate;
uniform sampler2D videoFrame;
uniform sampler2D videoFrame2;

void main(void) {
    highp float nx,ny,r,g,b,y,u,v;
    highp vec2 uv;
    highp vec4 txl,ux,vx;"
    nx=(textureCoordinate.x)/1024.0*720.0;
    ny=(textureCoordinate.y)/1024.0*480.0;
    y=texture2D(videoFrame,vec2(nx,ny)).r;
    uv=texture2D(videoFrame2,vec2(nx,ny)).ag;
    y=1.1643*(y-0.0625);
    u=uv[0]-0.5;
    v=uv[1]-0.5;
    r=y+1.5958*v;
    g=y-0.39173*u-0.81290*v;
    b=y+2.017*u;

    gl_FragColor=vec4(r,g,b,1);
};

OnSurfaceCreated仍然相同，但顶点的定义发生了一些变化：

static float squareVertices[] = { -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f,
        1.0f, 1.0f, };

private float textureVertices[] = { 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f,
        1.0f, 0.0f, };

OnSurfaceChanged:

    buffer = new int[2];
    GLES20.glGenTextures(2, buffer, 0);
    for (int i = 0; i < 2; i++) {
        int texture = buffer[i];
        Log.v("Texture", "Texture is at " + texture);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texture);
        GLES20.glPixelStorei(GLES20.GL_UNPACK_ALIGNMENT, GLES20.GL_TRUE);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D,
                GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_NEAREST);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D,
                GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_NEAREST);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D,
                GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D,
                GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);
    }

    buf = new byte[1024 * 1024];
    for (int i = 0; i < 1024 * 1024; i++) {
        buf[i] = 0;
    }
    buf2 = new byte[1024 * 1024];
    for (int i = 0; i < 1024 * 1024; i++) {
        buf2[i] = -128;
    }

    GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, buffer[0]);

    GLES20.glTexImage2D(GL10.GL_TEXTURE_2D, 0, GL10.GL_LUMINANCE, 1024,
            1024, 0, GL10.GL_LUMINANCE, GL10.GL_UNSIGNED_BYTE,
            ByteBuffer.wrap(buf));

    GLES20.glActiveTexture(GLES20.GL_TEXTURE1);
    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, buffer[1]);

    GLES20.glTexImage2D(GL10.GL_TEXTURE_2D, 0, GL10.GL_LUMINANCE_ALPHA,
            512, 512, 0, GL10.GL_LUMINANCE_ALPHA, GL10.GL_UNSIGNED_BYTE,
            ByteBuffer.wrap(buf2));

OnDrawFrame:

    GLES20.glViewport(0, 0, mWidth, mHeight);

    GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, buffer[0]);

    GLES20.glTexSubImage2D(GL10.GL_TEXTURE_2D, 0, 0, 0, Util.CAMWIDTH,
            Util.CAMHEIGHT, GL10.GL_LUMINANCE, GL10.GL_UNSIGNED_BYTE,
            ByteBuffer.wrap(mBuffer, 0, Util.CAMWIDTH * Util.CAMHEIGHT));

    GLES20.glActiveTexture(GLES20.GL_TEXTURE1);
    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, buffer[1]);

    GLES20.glTexSubImage2D(
            GL10.GL_TEXTURE_2D,
            0,
            0,
            0,
            Util.CAMWIDTH / 2,
            Util.CAMHEIGHT / 2,
            GL10.GL_LUMINANCE_ALPHA,
            GL10.GL_UNSIGNED_BYTE,
            ByteBuffer.wrap(mBuffer, Util.CAMWIDTH * Util.CAMHEIGHT,
                    Util.CAMWIDTH / 2 * Util.CAMHEIGHT).slice());

    GLES20.glClearColor(1.0f, .0f, .0f, .0f);

    GLES20.glUseProgram(program);

    GLES20.glUniform1i(GLES20.glGetUniformLocation(program, "videoFrame"),
            0);
    GLES20.glUniform1i(GLES20.glGetUniformLocation(program, "videoFrame2"),
            1);

    GLES20.glClearDepthf(1.0f);
    GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);

    int x = GLES20.glGetAttribLocation(program, "position");
    int y = GLES20.glGetAttribLocation(program, "inputTextureCoordinate");

    GLES20.glEnableVertexAttribArray(x);
    GLES20.glVertexAttribPointer(x, 2, GLES20.GL_FLOAT, false, 0, a);
    GLES20.glEnableVertexAttribArray(y);
    GLES20.glVertexAttribPointer(y, 2, GLES20.GL_FLOAT, false, 0, b);

    GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);