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PO"shader program is not linked" when running QT hello opengl
 

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  1. PO"shader program is not linked" when running QT hello opengl
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    <p>I have downloaded a QT OpenGL tutorial from <a href="http://releases.qt-project.org/learning/developerguides/qtopengltutorial/OpenGLTutorial.pdf" rel="nofollow">http://releases.qt-project.org/learning/developerguides/qtopengltutorial/OpenGLTutorial.pdf</a> and am trying to run the simplest example they have in there, which simply draws a triangle on top of a black background.</p> <p>I managed to compile the example, but when I run it, I only get a black window and the console reports the following:</p> <blockquote> <p>Starting /home/minas/Desktop/hello-opengl-build-Desktop_Qt_5_0_1_GCC_64bit-Debug/hello-opengl... QGLShaderProgram::uniformLocation( mvpMatrix ): shader program is not linked QGLShaderProgram::uniformLocation( color ): shader program is not linked QGLShaderProgram::attributeLocation( vertex ): shader program is not linked QGLShaderProgram::attributeLocation( vertex ): shader program is not linked QGLShaderProgram::attributeLocation( vertex ): shader program is not linked QGLShaderProgram::uniformLocation( mvpMatrix ): shader program is not linked QGLShaderProgram::uniformLocation( color ): shader program is not linked QGLShaderProgram::attributeLocation( vertex ): shader program is not linked QGLShaderProgram::attributeLocation( vertex ): shader program is not linked QGLShaderProgram::attributeLocation( vertex ): shader program is not linked QGLShaderProgram::uniformLocation( mvpMatrix ): shader program is not linked QGLShaderProgram::uniformLocation( color ): shader program is not linked QGLShaderProgram::attributeLocation( vertex ): shader program is not linked QGLShaderProgram::attributeLocation( vertex ): shader program is not linked QGLShaderProgram::attributeLocation( vertex ): shader program is not linked QGLShaderProgram::uniformLocation( mvpMatrix ): shader program is not linked QGLShaderProgram::uniformLocation( color ): shader program is not linked QGLShaderProgram::attributeLocation( vertex ): shader program is not linked QGLShaderProgram::attributeLocation( vertex ): shader program is not linked QGLShaderProgram::attributeLocation( vertex ): shader program is not linked</p> </blockquote> <p>The .pro file looks like this (the "unix:!mac" part is my addition, so it finds the OpenGL .so files).</p> <pre><code>QT += core gui opengl TARGET = hello-opengl TEMPLATE = app SOURCES += main.cpp\ glwidget.cpp HEADERS += glwidget.h OTHER_FILES += fragmentShader.fsh\ vertexShader.vsh RESOURCES += resources.qrc unix:!mac{ QMAKE_LFLAGS += -Wl,--rpath=/usr/lib64/nvidia-current QMAKE_LFLAGS += -L/usr/lib64/nvidia-current } </code></pre> <p>The output of "glxinfo | grep -i opengl" is</p> <pre><code>OpenGL vendor string: NVIDIA Corporation OpenGL renderer string: GeForce 9800 GT/PCIe/SSE2 OpenGL version string: 2.1.2 NVIDIA 304.64 OpenGL shading language version string: (null) OpenGL extensions: </code></pre> <p>and the part of the code that does the actual rendering is</p> <pre><code>void GlWidget::paintGL() { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); QMatrix4x4 mMatrix; QMatrix4x4 vMatrix; // shaderProgram initialized in initializeGL() shaderProgram.bind(); // "mvpMatrix", "color" and "vertex" do exist in the shaders shaderProgram.setUniformValue("mvpMatrix", pMatrix * vMatrix * mMatrix); shaderProgram.setUniformValue("color", QColor(Qt::white)); shaderProgram.setAttributeArray("vertex", vertices.constData()); shaderProgram.enableAttributeArray("vertex"); glDrawArrays(GL_TRIANGLES, 0, vertices.size()); shaderProgram.disableAttributeArray("vertex"); shaderProgram.release(); } </code></pre> <p>Also, as a side-question, why does the output of "glxinfo | grep -i opengl" contain the line</p> <blockquote> <p>OpenGL shading language version string: (null)</p> </blockquote> <p>(kinda seems relevant to me... is it?)</p> <hr> <h2>EDIT 1</h2> <p>The <code>shaderProgram</code> is declared in my subclass of <code>QGLWidget</code>, which I call <code>GLWidget</code> and initialized in <code>initializeGL</code> as such:</p> <pre><code>void GlWidget::initializeGL() { glEnable(GL_DEPTH_TEST); glEnable(GL_CULL_FACE); qglClearColor(QColor(Qt::black)); shaderProgram.addShaderFromSourceFile(QGLShader::Vertex, ":/vertexShader.vsh"); shaderProgram.addShaderFromSourceFile(QGLShader::Fragment, ":/fragmentShader.fsh"); shaderProgram.link(); vertices &lt;&lt; QVector3D(1, 0, -2) &lt;&lt; QVector3D(0, 1, -2) &lt;&lt; QVector3D(-1, 0, -2); } </code></pre> <hr> <h2>EDIT 2</h2> <p>Here is my initializeGL() method:</p> <pre><code>void GlWidget::initializeGL() { glEnable(GL_DEPTH_TEST); glEnable(GL_CULL_FACE); qglClearColor(QColor(Qt::black)); shaderProgram.addShaderFromSourceFile(QGLShader::Vertex, ":/vertexShader.vsh"); shaderProgram.addShaderFromSourceFile(QGLShader::Fragment, ":/fragmentShader.fsh"); shaderProgram.link(); vertices &lt;&lt; QVector3D(1, 0, -2) &lt;&lt; QVector3D(0, 1, -2) &lt;&lt; QVector3D(-1, 0, -2); } </code></pre> <p>and putting</p> <pre><code>qDebug() &lt;&lt; shaderProgram.log(); exit(0); </code></pre> <p>immediately after the call to link() above does not produce any output.</p>
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    1. CO"*shaderProgram was initialized in the class constructor*" Was it? The error is saying that the program wasn't properly created and linked.
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      1. PO"shader program is not linked" when running QT hello opengl
      1. USNicol Bolas
    2. COThanks for your response, let me edit my original post with some more info. Bear in mind that I am trying to run a tutorial example which comes with source code from the QT website, so it is supposed to work as it is.
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      1. PO"shader program is not linked" when running QT hello opengl
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    3. COshaderProgram.log() just returns a string containing the OpenGL shader compilation log. Try printing this information out to console with qDebug() << shaderProgram.log() and post the output if there is anything.
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      1. PO"shader program is not linked" when running QT hello opengl
      1. USSir Digby Chicken Caesar
 

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