部署到win8上的openframeworks

来源：互联网发布：淘宝新店0流量编辑：程序博客网时间：2024/05/22 07:06

微软发布了一套用于部署到win8上的openframeworks库，可以用于编写universal程序~

于是迫不及待的想要试一试~

于是用example/gl/textureScreengrabExample的代码：

void ofApp::setup(){counter = 0;ofSetCircleResolution(100);texScreen.allocate(1600, 900, GL_RGB);ofBackground(230, 230, 240);}

void ofApp::update(){counter += 1;}

void ofApp::draw(){// 1st, draw on screen:ofSetHexColor(0x66CC33);ofRect(100, 100, 300, 300);ofSetHexColor(0xffffff);ofPushMatrix();ofTranslate(200, 200, 0);ofRotate(counter, 0, 0, 1);ofCircle(0, 0, 80);ofCircle(100, 0, 10);// a small oneofPopMatrix();ofSetHexColor(0x333333);ofDrawBitmapString("(a) on screen", 150, 200);ofSetHexColor(0xFFCC33);ofCircle(mouseX, mouseY, 20);// 2nd, grab a portion of the screen into a texture// this is quicker then grabbing into an ofImage// because the transfer is done in the graphics card// as opposed to bringing pixels back to memory// note: you need to allocate the texture to the right sizetexScreen.loadScreenData(0, 0, 1600, 900);// finally, draw that texture on screen, how ever you want// (note: you can even draw the texture before you call loadScreenData, // in order to make some trails or feedback type effects)ofPushMatrix();ofSetHexColor(0xffffff);ofTranslate(550, 300, 0);//glRotatef(counter, 0.1f, 0.03f, 0);float width = 200 + 100 * sin(counter / 200.0f);float height = 200 + 100 * sin(counter / 200.0f);texScreen.draw(-width / 2, -height / 2, width, height);ofPopMatrix();ofPushMatrix();ofSetHexColor( 0xffffff );ofTranslate( 700 , 210 , 0 );ofRotate( counter , 0.1f , 0.03f , 0 );texScreen.draw( -50 , -50 , 100 , 100 );ofPopMatrix();ofSetHexColor(0x333333);ofDrawBitmapString("(b) in a texture, very meta!", 500, 200);}

果不其然的运行得不到正确的结果~

一番排查之后~发现下面这一段代码：

void Renderer::CreateDeviceDependentResources(){if (!m_loadingComplete){m_deviceResources->aquireContext();ofmain();m_loadingComplete = true;m_deviceResources->releaseContext();}}

void DeviceResources::aquireContext(){if (!m_eglSurface)return;std::lock_guard<std::mutex> guard(m_mutex);if (!eglMakeCurrent(m_eglDisplay, m_eglSurface, m_eglSurface, m_eglContext)){throw std::runtime_error("DeviceResouces: failed to make EGL context current");}}

eglMakeCurrent的原型如下：

EGLBoolean eglMakeCurrent(EGLDisplay display, <span style="white-space:pre"></span>EGLSurface draw, <span style="white-space:pre"></span>EGLSurface read, <span style="white-space:pre"></span>EGLContext context);

具体可参见：eglMakeCurrent

而loadScreenData()内部调用了glCopyTexSubImage2D()实现

而在执行ofmain之前执行已经调用了eglMakeCurrent()了，由于调用了eglMakeCurrent之后，不能进行任何像素数据读回操作，glCopyTexSubImage2D无法得到数据，所以上述代码无法得到正确的结果

0 0