android - 在 Android 中使用 FBO 录制屏幕

Question

我正在开发记录 Unity 游戏屏幕的 Android 插件。为此，我使用了 OpenGL FBO。伪代码很简单，如下所示:

// Bind frame buffer as a render target
mFrameBuffer.bind();

// Render scene to frame buffer
renderScene();

// Restore rendering target, unbind FBO
mFrameBuffer.unbind();

// Draw texture into display
mTexture.draw(mFrameBuffer.getTexture());

// Make video surface a rendering target
videoCapture.captureFrame(mFrameBuffer.getTexture());

输出视频没问题，但我在使用从 FBO 获取的离屏纹理渲染到窗口显示时遇到了问题。我检查了我的代码，发现对 glDrawArray 的调用失败，错误代码为 GL_INVALID_OPERATION
。

我的渲染代码

   public void draw(int textureId) {
    this.shader.use();

    GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
    Log.getPossibleGLError("active texture0");
    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);
    Log.getPossibleGLError("bind texture when redraw");

    int uOrientationM = this.shader.getAttributeLocation("uOrientationM");
    Log.getPossibleGLError("get orientation matrix");
    int uTransformM = this.shader.getAttributeLocation("uTransformM");
    Log.getPossibleGLError("get transform matrix");

    GLES20.glUniformMatrix4fv(uOrientationM, 1, false, this.orientationMatrix, 0);

    Log.getPossibleGLError("set orientation matrix when redraw");

    GLES20.glUniformMatrix4fv(uTransformM, 1, false, this.transformMatrix, 0);

    Log.getPossibleGLError("set uniform matrix when redraw");

    renderQuad(this.shader.getAttributeLocation("aPosition"));

    Log.getPossibleGLError("render quad when redraw");

    this.shader.unUse();
   }

   private void renderQuad(int aPosition) {
      GLES20.glVertexAttribPointer(aPosition, 2, GLES20.GL_BYTE, false, 0, this.fullQuadVertices);
      Log.getPossibleGLError("get vertex attrib pointer");
      GLES20.glEnableVertexAttribArray(aPosition);
      Log.getPossibleGLError("enable vertex array");
      GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
      // error occurs after execute glDrawArrays
      Log.getPossibleGLError("draw array ");
   } 

此代码在渲染到 videoSurface 时运行良好，但在渲染到窗口显示时失败。
我的问题有什么解决方案吗？

渲染以显示日志:发生 GL_INVALID_OPERATION 错误

glUseProgram(program = 31)
glActiveTexture(texture = GL_TEXTURE0)
glGetError(void) = (GLenum) GL_NO_ERROR
glBindTexture(target = GL_TEXTURE_2D, texture = 13)
glGetError(void) = (GLenum) GL_NO_ERROR
glGetError(void) = (GLenum) GL_NO_ERROR
glGetError(void) = (GLenum) GL_NO_ERROR
glUniformMatrix4fv(location = 0, count = 1, transpose = false, value = [1.0, 0.0, 0.0, 0.0, -0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0])
glGetError(void) = (GLenum) GL_NO_ERROR
glUniformMatrix4fv(location = 1, count = 1, transpose = false, value = [1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0])
glGetError(void) = (GLenum) GL_NO_ERROR
glVertexAttribPointer(indx = 0, size = 2, type = GL_BYTE, normalized = false, stride = 0, ptr = 0x42b1ae38)
glGetError(void) = (GLenum) GL_NO_ERROR
glEnableVertexAttribArray(index = 0)
glGetError(void) = (GLenum) GL_NO_ERROR
glValidateProgram(program = 31)
glGetError(void) = (GLenum) GL_NO_ERROR
glGetProgramiv(program = 31, pname = GL_VALIDATE_STATUS, params = [1])
glGetProgramiv(program = 31, pname = GL_LINK_STATUS, params = [1])
glDrawArrays(mode = GL_TRIANGLE_STRIP, first = 0, count = 4)
glGetError(void) = (GLenum) GL_INVALID_OPERATION
glGetError(void) = (GLenum) GL_NO_ERROR

渲染到视频日志:运行正常，没有错误

glUseProgram(program = 31)
glActiveTexture(texture = GL_TEXTURE0)
glGetError(void) = (GLenum) GL_NO_ERROR
glBindTexture(target = GL_TEXTURE_2D, texture = 13)
glGetError(void) = (GLenum) GL_NO_ERROR
glGetAttribLocation(program = 31, name = uOrientationM) = (GLint) -1
glGetError(void) = (GLenum) GL_NO_ERROR
glGetUniformLocation(program = 31, name = uOrientationM) = (GLint) 0
glGetError(void) = (GLenum) GL_NO_ERROR
glGetError(void) = (GLenum) GL_NO_ERROR
glGetAttribLocation(program = 31, name = uTransformM) = (GLint) -1
glGetError(void) = (GLenum) GL_NO_ERROR
glGetUniformLocation(program = 31, name = uTransformM) = (GLint) 1
glGetError(void) = (GLenum) GL_NO_ERROR
glGetError(void) = (GLenum) GL_NO_ERROR
glUniformMatrix4fv(location = 0, count = 1, transpose = false, value = [1.0, 0.0, 0.0, 0.0, -0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0])
glGetError(void) = (GLenum) GL_NO_ERROR
glUniformMatrix4fv(location = 1, count = 1, transpose = false, value = [1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0])
glGetError(void) = (GLenum) GL_NO_ERROR
glGetAttribLocation(program = 31, name = aPosition) = (GLint) 0
glGetError(void) = (GLenum) GL_NO_ERROR
glVertexAttribPointer(indx = 0, size = 2, type = GL_BYTE, normalized = false, stride = 0, ptr = 0x42b1ae38)
glGetError(void) = (GLenum) GL_NO_ERROR
glEnableVertexAttribArray(index = 0)
glGetError(void) = (GLenum) GL_NO_ERROR
glValidateProgram(program = 31)
glGetError(void) = (GLenum) GL_NO_ERROR
glGetProgramiv(program = 31, pname = GL_VALIDATE_STATUS, params = [1])
glGetProgramiv(program = 31, pname = GL_LINK_STATUS, params = [1])
glVertexAttribPointerData(indx = 0, size = 2, type = GL_BYTE, normalized = false, stride = 2, ptr = 0x??, minIndex = 0, maxIndex = 4)
glDrawArrays(mode = GL_TRIANGLE_STRIP, first = 0, count = 4)
glGetError(void) = (GLenum) GL_NO_ERROR
glGetError(void) = (GLenum) GL_NO_ERROR
glUseProgram(program = 0)

Answer 1

经过对 OpenGl 的多次调查，我终于解决了这个问题。问题是当我尝试将纹理重绘到屏幕时，数组缓冲区和元素数组缓冲区被错误地指向。解决方案非常简单，我创建了自己的数组缓冲区和元素数组缓冲区，然后在尝试重绘到屏幕之前绑定(bind)它们。它工作正常，没有错误 :D