Question

我相机的预览呈现为纹理。我有textureId，我正试图在FBO上渲染纹理，所以我可以glReadPixels。

当我实际读取像素时，它们看起来都是黑色的。

这是我目前正在使用的代码：

//called when the camera first connects to the texture
public void initBackBuffer()
    {
  // For use in getFramePixels()
        intBuffer = ByteBuffer.allocateDirect(width *
            height * 4)
            .order(ByteOrder.nativeOrder())
            .asIntBuffer();
        IntBuffer framebuffer = IntBuffer.allocate(1);
        glGenFramebuffers(1, framebuffer);
        glBindFramebuffer(GL_FRAMEBUFFER, framebuffer.get(0));
        int status = glGetError();
        if(status != GL_NO_ERROR)
        {
            Log.e("RENDERER", status + "");
        }

        IntBuffer depthBufferName = IntBuffer.allocate(1);

        glGenRenderbuffers(1, depthBufferName);
        glBindRenderbuffer(GL_RENDERBUFFER, depthBufferName.get(0));
        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, width, height);
        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER,
                depthBufferName.get(0));
       glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
                mTangoCameraTexture.getTextureId(), 0);
        mOffscreenBuffer = framebuffer.get(0);
        status = glCheckFramebufferStatus(GL_FRAMEBUFFER);

        if(status != GL_FRAMEBUFFER_COMPLETE) {
            if(status == GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT)
                Log.e("RENDERER","GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT");
            if(status == GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT)
                Log.e("RENDERER", "GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT_EXT");
            Log.e("RENDERER", "FRAMEBUFFER ERROR:"+status);

        }
        glBindFramebuffer( GL_FRAMEBUFFER, 0 );

    }
// called onFrameAvailable
public void getFramePixels() {
    glBindFramebuffer(GL_FRAMEBUFFER, mOffscreenBuffer);
    int status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
    if(status != GL_FRAMEBUFFER_COMPLETE)
    {
        Log.e(TAG, "FRAMEBUFFER STATUS:"+status);
    }
    glReadPixels(0, 0, width, height, GL_RGBA,
            GL_UNSIGNED_BYTE,
            intBuffer.clear());
    StringBuilder str = new StringBuilder();
    for(int i = 0; i < intBuffer.capacity(); i++)
    {
        str.append(intBuffer.get(););
    }
    Log.d(TAG, "IMAGE:" + str.toString());
    glBindFramebuffer(GL_FRAMEBUFFER, 0);

}

如果我在屏幕上显示纹理，我就能看到它 - 所以不会实际绑定到相机的纹理。

修改：由于某种原因GL_INVALID_OPERATION发生了glFramebufferTexture2D(GL_FRAMEBUFFER,GL_COLOR_ATTACHMENT0,GL_TEXTURE_2D, getTextureId(), 0);。

来自文档：

如果零绑定到目标，则生成GL_INVALID_OPERATION。如果textarget和纹理不兼容，则生成GL_INVALID_OPERATION。

我的textureId是1。

Answer 1

更仔细地阅读文档。您的纹理ID可能为1，但您当前绑定到目标的内容可能实际为0.如果您不打电话glBindTexture(GL_TEXTURE_2D, mTangoCameraTexture.getTextureId());，则GL_TEXTURE_2D（目标）是您设置的任何内容最后，我倾向于说可能是0。

如果您发现围绕glReadPixels()存在性能问题，则应考虑将其与像素缓冲区对象一起使用。

Android OpenGL ES读取纹理像素

1 个答案: