Android OpenGL ES 2.0渲染到帧缓冲区/纹理会产生黑色纹理

我正在使用libgdx，但这几乎是普通的opengles2.0。只要试着忽略Gdx.gl前缀无处不在^^^我正在我的桌面和android设备上测试它，这两种情况下的情况都是一样的

我的窗口调整事件中有以下代码。如果已经创建了帧缓冲区和相关纹理，则应该删除它们，然后制作一些大小合适的新纹理。我不确定像我这样删除纹理和帧缓冲区是否正确

    if (depthTexture >= 0)
    {
        Gdx.gl.glDeleteTexture(depthTexture);
        depthTexture = -1;
    }
    if (colorTexture >= 0)
    {
        Gdx.gl.glDeleteTexture(colorTexture);
        colorTexture = -1;
    }
    if (depthBuffer >= 0)
    {
        Gdx.gl.glDeleteFramebuffer(depthBuffer);
        depthBuffer = -1;
    }

    IntBuffer intBuffer = BufferUtils.newIntBuffer(16); // See http://lwjgl.org/forum/index.php?topic=1314.0;wap2
    intBuffer.clear();
    Gdx.gl.glGenFramebuffers(1, intBuffer);
    frameBuffer = intBuffer.get(0);


    intBuffer.clear();
    Gdx.gl.glGenTextures(1, intBuffer);
    colorTexture = intBuffer.get(0);
    Gdx.gl.glBindTexture(GL20.GL_TEXTURE_2D, colorTexture);
    Gdx.gl.glTexImage2D(GL20.GL_TEXTURE_2D, 0, GL20.GL_RGBA, width, height
            , 0, GL20.GL_RGBA, GL20.GL_UNSIGNED_BYTE, null);

    Gdx.gl.glTexParameteri(GL20.GL_TEXTURE_2D, GL20.GL_TEXTURE_MIN_FILTER, GL20.GL_NEAREST);
    Gdx.gl.glTexParameteri(GL20.GL_TEXTURE_2D, GL20.GL_TEXTURE_MAG_FILTER, GL20.GL_NEAREST);

    Gdx.gl.glBindTexture(GL20.GL_TEXTURE_2D, 0);

    intBuffer.clear();
    Gdx.gl.glGenTextures(1, intBuffer);
    depthTexture = intBuffer.get(0);
    Gdx.gl.glBindTexture(GL20.GL_TEXTURE_2D, depthTexture);
    Gdx.gl.glTexImage2D(GL20.GL_TEXTURE_2D, 0, GL20.GL_DEPTH_COMPONENT, width, height
            , 0, GL20.GL_DEPTH_COMPONENT, GL20.GL_UNSIGNED_SHORT, null);

    Gdx.gl.glTexParameteri(GL20.GL_TEXTURE_2D, GL20.GL_TEXTURE_MIN_FILTER, GL20.GL_NEAREST);
    Gdx.gl.glTexParameteri(GL20.GL_TEXTURE_2D, GL20.GL_TEXTURE_MAG_FILTER, GL20.GL_NEAREST);

    Gdx.gl.glBindTexture(GL20.GL_TEXTURE_2D, 0);


    Gdx.gl.glBindFramebuffer(GL20.GL_FRAMEBUFFER, frameBuffer);

    Gdx.gl.glFramebufferTexture2D(GL20.GL_FRAMEBUFFER, GL20.GL_COLOR_ATTACHMENT0
            , GL20.GL_TEXTURE_2D, colorTexture, 0);

    Gdx.gl.glFramebufferTexture2D(GL20.GL_FRAMEBUFFER, GL20.GL_DEPTH_ATTACHMENT
            , GL20.GL_TEXTURE_2D, depthTexture, 0);


    int status = Gdx.gl.glCheckFramebufferStatus(GL20.GL_FRAMEBUFFER);
    if (status != GL20.GL_FRAMEBUFFER_COMPLETE)
    {
        System.out.println("frame buffer not complete. status " + Integer.toHexString(status));
        System.exit(0);
    }


    Gdx.gl.glBindFramebuffer(GL20.GL_FRAMEBUFFER, 0);

    status = Gdx.gl.glCheckFramebufferStatus(GL20.GL_FRAMEBUFFER);
    if (status != GL20.GL_FRAMEBUFFER_COMPLETE)
    {
        System.out.println("default buffer not complete. status " + Integer.toHexString(status));
        System.exit(0);
    }

我根本不确定在设置渲染缓冲区或颜色纹理或深度纹理附件时是否出错。无论如何，请转到渲染循环

            // update cameras and things


    // setup rendering to off screen framebuffer
    Gdx.gl.glBindFramebuffer(GL20.GL_FRAMEBUFFER, frameBuffer);
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT | GL20.GL_DEPTH_BUFFER_BIT);    
    Gdx.gl.glViewport(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());

    // draw things

    // setup rendering to default framebuffer

    Gdx.gl.glBindFramebuffer(GL20.GL_FRAMEBUFFER, 0);
    Gdx.gl.glViewport(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT | GL20.GL_DEPTH_BUFFER_BIT);

    shader.begin();

    // setup shader stuff 

    Gdx.gl.glActiveTexture(0);
    Gdx.gl.glBindTexture(GL20.GL_TEXTURE_2D, depthTexture);
    shader.setUniformi("u_fbDepth", 0);

    Gdx.gl.glActiveTexture(1);
    Gdx.gl.glBindTexture(GL20.GL_TEXTURE_2D, colorTexture);
    shader.setUniformi("u_fbColor", 1);

    // draw things with shader 

    shader.end();

再一次，我不确定我是否把事情安排得正确。希望这里的想法非常清楚。渲染到屏幕外帧缓冲区，然后使用该帧缓冲区中的深度和颜色纹理作为纹理，在渲染到默认帧缓冲区的最终着色器中进行采样

---

然而，在我的片段着色器中结束的深度和颜色纹理只是空的。黑屏。我知道碎片着色器不是问题所在-如果我对不同的纹理进行采样，我会看到预期的纹理。我知道绘图本身不是问题所在-如果我将要渲染的内容直接渲染到屏幕外的帧缓冲区，然后直接渲染到默认的帧缓冲区，我会看到我所期望的内容。

我得到了它。设置活动纹理有点困难。函数glActiveTexture需要一个GL_TEXTURE0类型常量，但着色器uniform只希望是常量名称中的整数

基本上

Gdx.gl.glActiveTexture(0);
Gdx.gl.glBindTexture(GL20.GL_TEXTURE_2D, depthTexture);
shader.setUniformi("u_fbDepth", 0);

Gdx.gl.glActiveTexture(1);
Gdx.gl.glBindTexture(GL20.GL_TEXTURE_2D, colorTexture);
shader.setUniformi("u_fbColor", 1);

需要

Gdx.gl.glActiveTexture(GL20.GL_TEXTURE0);
Gdx.gl.glBindTexture(GL20.GL_TEXTURE_2D, depthTexture);
shader.setUniformi("u_fbDepth", 0);

Gdx.gl.glActiveTexture(GL20.GL_TEXTURE1);
Gdx.gl.glBindTexture(GL20.GL_TEXTURE_2D, colorTexture);
shader.setUniformi("u_fbColor", 1);