[osg-users] Trouble with a simple shader program.

Alexander Wieser alexander.wieser at crystalbyte.de
Sat Apr 11 16:24:19 PDT 2015


I am currently working on my bachelor thesis which involves the OpenSceneGraph. One task is to apply a distortion shader to a rendered texture.

Unfortunately I am failing in getting any shader to work at all.
After spending the last couple of days researching and reading books, I managed to get several shaders running in other libraries, be it online using WebGL or directly using OpenGL. I simply can't get it running using OSG.

The code initializing the program is this.


// A simple 4 vertex rectangular geometry drawable.
Plane* plane = new Plane(40);

osg::Program* program = new osg::Program();
program->setName("Debug Shader");

// This refers to a Geode.
osg::StateSet& state = *this->getOrCreateStateSet();
state.setAttributeAndModes(program, osg::StateAttribute::ON);

boost::filesystem::path currentPath(boost::filesystem::current_path());

// Init vertex shader.
RTT::log(RTT::Debug) << "Loading vertex shader."<< RTT::endlog();
osg::Shader* vertexShader = new osg::Shader(osg::Shader::VERTEX);
vertexShader->loadShaderSourceFromFile(currentPath.string() + "/../resources/shaders/debug.vert");

// Init fragment shader.
RTT::log(RTT::Debug) << "Loading fragment shader."<< RTT::endlog();
osg::Shader* fragmentShader = new osg::Shader(osg::Shader::FRAGMENT);
fragmentShader->loadShaderSourceFromFile(currentPath.string() + "/../resources/shaders/debug.frag");

Vertex Shader


#version 430

uniform mat4 osg_ModelViewProjectionMatrix;
in vec4 osg_Vertex;

void main() {
gl_Position = osg_ModelViewProjectionMatrix * osg_Vertex;

Fragment Shader


#version 430

layout(location = 0) out vec4 FragColor;

void main() {
FragColor = vec4(1.0, 0.0, 0.0, 1.0);

As you can see, the program is not that complicated and does compile fine.
Unfortunately I don't see anything on the screen. There is no model.
If I remove the program and simply use the built in lighting, coloring and texturing support it renders fine.

Any help is greatly appreciated.

Thank you!


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