安卓4.3 PBO不工作

问题描述

我使用 PBO 采取截图。但是，结果图像是全黑的。这工作完全正常，而不 PBO 。有没有办法，我必须这样做之前先照顾好任何事情吗？

我甚至通过渲染到 FBO 键，然后用试 GLES30.glReadBuffer（GLES30.GL_COLOR_ATTACHMENT0），无希望

 公共无效SetupPBO（）{
    GLES30.glGenBuffers（1，pbuffer而使，0）;
    GLES30.glBindBuffer（GLES30.GL_PIXEL_PACK_BUFFER，pbuffer而使[0]）;
    INT大小=（int）的this.mScreenHeight *（INT）this.mScreenWidth * 4;
    GLES30.glBufferData（GLES30.GL_PIXEL_PACK_BUFFER，大小，空，GLES30.GL_DYNAMIC_READ）;
    checkGlError（glReadBuffer）;
    GLES30.glBindBuffer（GLES30.GL_PIXEL_PACK_BUFFER，0）;
}

私人无效渲染（浮动[] M）{
    ....... //正常渲染逻辑
    exportBitmap（）;
}

 私人无效exportBitmap（）{
    INT screenshotSize =（int）的this.mScreenWidth *（INT）this.mScreenHeight;
    ByteBuffer的BB = ByteBuffer.allocateDirect（screenshotSize * 4）;
    bb.order（ByteOrder.nativeOrder（））;

    //设置目标帧缓冲读
    GLES30.glReadBuffer（GLES30.GL_FRONT）;
    checkGlError（glReadBuffer）;
    GLES30.glBindBuffer（GLES30.GL_PIXEL_PACK_BUFFER，pbuffer而使[0]）;
    GLES30.glReadPixels（0，0，（int）的mScreenWidth，（int）的mScreenHeight，GL10.GL_RGBA，GL10.GL_UNSIGNED_BYTE，BB）; //＆LT; ------不工作?????

    INT pixelsBuffer [] =新的INT [screenshotSize]
    。bb.asIntBuffer（）得到（pixelsBuffer）;
    BB = NULL;

    的for（int i = 0; I＆LT; screenshotSize ++我）{
        //阿尔法和绿色通道的位置是pserved而$ P $
        //红色和蓝色互换
        pixelsBuffer [I] =（（pixelsBuffer [1]  - 安培; 0xff00ff00））
                    | （（pixelsBuffer [1]  - 安培; 0x000000ff）＆LT;＆LT; 16）
                    | （（pixelsBuffer [1]  - 安培; 0x00ff0000）＆GT;＆GT; 16）;
    }

    点阵位图= Bitmap.createBitmap（（INT）mScreenWidth，（INT）mScreenHeight，Bitmap.Config.ARGB_8888）;
    bitmap.setPixels（pixelsBuffer，screenshotSize  - （int）的mScreenWidth， - （int）的mScreenWidth，0，0，（int）的mScreenWidth，（int）的mScreenHeight）;
    SaveBitmap（位）;
}
 

解决方案

  GLES30.glReadPixels（0，0，（INT）mScreenWidth，（INT）mScreenHeight，GL10.GL_RGBA，GL10。 GL_UNSIGNED_BYTE，BB）;
 

BB是跨preT为您的PBO抵消。因此，你写了缓冲液（在某些驱动程序中的code引起死机）。你应该通过BB 0代替。以检索从PBO数据使用glMapBuffer。

I am using PBO to take screenshot. However, the result image is all black. It works perfectly fine without PBO. Is there any thing that I need to take care before doing this ?

I even tried by rendering to a FBO and then use GLES30.glReadBuffer(GLES30.GL_COLOR_ATTACHMENT0), no hope

public void SetupPBO(){
    GLES30.glGenBuffers(1, pbuffers, 0);
    GLES30.glBindBuffer(GLES30.GL_PIXEL_PACK_BUFFER, pbuffers[0]);
    int size = (int)this.mScreenHeight *  (int)this.mScreenWidth * 4;
    GLES30.glBufferData(GLES30.GL_PIXEL_PACK_BUFFER, size, null, GLES30.GL_DYNAMIC_READ);
    checkGlError("glReadBuffer");
    GLES30.glBindBuffer(GLES30.GL_PIXEL_PACK_BUFFER, 0);
}

private void Render(float[] m) {
    .......//Normal render logic
    exportBitmap();
}

 private void exportBitmap() {
    int screenshotSize = (int)this.mScreenWidth * (int)this.mScreenHeight;
    ByteBuffer bb = ByteBuffer.allocateDirect(screenshotSize * 4);
    bb.order(ByteOrder.nativeOrder());

    // set the target framebuffer to read
    GLES30.glReadBuffer(GLES30.GL_FRONT);
    checkGlError("glReadBuffer");
    GLES30.glBindBuffer(GLES30.GL_PIXEL_PACK_BUFFER, pbuffers[0]);
    GLES30.glReadPixels(0, 0, (int)mScreenWidth, (int)mScreenHeight, GL10.GL_RGBA, GL10.GL_UNSIGNED_BYTE, bb);  //<------ not working ?????

    int pixelsBuffer[] = new int[screenshotSize];
    bb.asIntBuffer().get(pixelsBuffer);
    bb = null;

    for (int i = 0; i < screenshotSize; ++i) {
        // The alpha and green channels' positions are preserved while the
        // red and blue are swapped
        pixelsBuffer[i] = ((pixelsBuffer[i] & 0xff00ff00))
                    | ((pixelsBuffer[i] & 0x000000ff) << 16)
                    | ((pixelsBuffer[i] & 0x00ff0000) >> 16);
    }

    Bitmap bitmap = Bitmap.createBitmap((int)mScreenWidth, (int)mScreenHeight, Bitmap.Config.ARGB_8888);
    bitmap.setPixels(pixelsBuffer, screenshotSize - (int)mScreenWidth, -(int)mScreenWidth, 0, 0, (int)mScreenWidth, (int)mScreenHeight);
    SaveBitmap(bitmap);
}

解决方案

GLES30.glReadPixels(0, 0, (int)mScreenWidth, (int)mScreenHeight, GL10.GL_RGBA, GL10.GL_UNSIGNED_BYTE, bb);

bb is interpret as an offset in your PBO. Thus you're writing out of buffer (On some drivers this code cause crash). You should pass 0 instead of bb. To retrive the data from PBO use glMapBuffer.

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