OSG 中 常用的 Uniforms

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osg中的 Uniforms主要存在两个地方，一个是SceneView中，void SceneView::updateUniforms()

void SceneView::updateUniforms()
{
    if (!_localStateSet)
    {
        _localStateSet = new osg::StateSet;
    }

    if (!_localStateSet) return;
    
    if ((_activeUniforms & FRAME_NUMBER_UNIFORM) && _frameStamp.valid())
    {
        osg::Uniform* uniform = _localStateSet->getOrCreateUniform("osg_FrameNumber",osg::Uniform::UNSIGNED_INT);
        uniform->set(_frameStamp->getFrameNumber());        
    }
    
    if ((_activeUniforms & FRAME_TIME_UNIFORM) && _frameStamp.valid())
    {
        osg::Uniform* uniform = _localStateSet->getOrCreateUniform("osg_FrameTime",osg::Uniform::FLOAT);
        uniform->set(static_cast<float>(_frameStamp->getReferenceTime()));
    }
    
    if ((_activeUniforms & DELTA_FRAME_TIME_UNIFORM) && _frameStamp.valid())
    {
        float delta_frame_time = (_previousFrameTime != 0.0) ? static_cast<float>(_frameStamp->getReferenceTime()-_previousFrameTime) : 0.0f;
        _previousFrameTime = _frameStamp->getReferenceTime();
        
        osg::Uniform* uniform = _localStateSet->getOrCreateUniform("osg_DeltaFrameTime",osg::Uniform::FLOAT);
        uniform->set(delta_frame_time);
    }
    
    if ((_activeUniforms & SIMULATION_TIME_UNIFORM) && _frameStamp.valid())
    {
        osg::Uniform* uniform = _localStateSet->getOrCreateUniform("osg_SimulationTime",osg::Uniform::FLOAT);
        uniform->set(static_cast<float>(_frameStamp->getSimulationTime()));
    }
    
    if ((_activeUniforms & DELTA_SIMULATION_TIME_UNIFORM) && _frameStamp.valid())
    {
        float delta_simulation_time = (_previousSimulationTime != 0.0) ? static_cast<float>(_frameStamp->getSimulationTime()-_previousSimulationTime) : 0.0f;
        _previousSimulationTime = _frameStamp->getSimulationTime();
        
        osg::Uniform* uniform = _localStateSet->getOrCreateUniform("osg_DeltaSimulationTime",osg::Uniform::FLOAT);
        uniform->set(delta_simulation_time);
    }
    
    if (_activeUniforms & VIEW_MATRIX_UNIFORM)
    {
        osg::Uniform* uniform = _localStateSet->getOrCreateUniform("osg_ViewMatrix",osg::Uniform::FLOAT_MAT4);
        uniform->set(getViewMatrix());
    }

    if (_activeUniforms & VIEW_MATRIX_INVERSE_UNIFORM)
    {
        osg::Uniform* uniform = _localStateSet->getOrCreateUniform("osg_ViewMatrixInverse",osg::Uniform::FLOAT_MAT4);
        uniform->set(osg::Matrix::inverse(getViewMatrix()));
    }

}

不过默认的是： DEFAULT_UNIFORMS

       enum ActiveUniforms
        {
            FRAME_NUMBER_UNIFORM            = 1,
            FRAME_TIME_UNIFORM              = 2,
            DELTA_FRAME_TIME_UNIFORM        = 4,
            SIMULATION_TIME_UNIFORM         = 8,
            DELTA_SIMULATION_TIME_UNIFORM   = 16,
            VIEW_MATRIX_UNIFORM             = 32,
            VIEW_MATRIX_INVERSE_UNIFORM     = 64,
            DEFAULT_UNIFORMS                = FRAME_NUMBER_UNIFORM |
                                              FRAME_TIME_UNIFORM |
                                              DELTA_FRAME_TIME_UNIFORM |
                                              SIMULATION_TIME_UNIFORM |
                                              DELTA_SIMULATION_TIME_UNIFORM |
                                              VIEW_MATRIX_UNIFORM |
                                              VIEW_MATRIX_INVERSE_UNIFORM,
            ALL_UNIFORMS                    = 0x7FFFFFFF
        };

另一个是在osg::State中，

    _modelViewMatrixUniform = new Uniform(Uniform::FLOAT_MAT4,"osg_ModelViewMatrix");
    _projectionMatrixUniform = new Uniform(Uniform::FLOAT_MAT4,"osg_ProjectionMatrix");
    _modelViewProjectionMatrixUniform = new Uniform(Uniform::FLOAT_MAT4,"osg_ModelViewProjectionMatrix");
    _normalMatrixUniform = new Uniform(Uniform::FLOAT_MAT3,"osg_NormalMatrix");

要使用这些Uniforms，需要：

viewer->realize();
	osg::State* state = viewer->getCamera()->getGraphicsContext()->getState();
	state->setUseModelViewAndProjectionUniforms(true);