QTechnique Class

Detailed Description

A Qt3DRender::QTechnique specifies a set of Qt3DRender::QRenderPass objects, Qt3DRender::QFilterKey objects, Qt3DRender::QParameter objects and a Qt3DRender::QGraphicsApiFilter, which together define a rendering technique the given graphics API can render. The filter keys are used by Qt3DRender::QTechniqueFilter to select specific techniques at specific parts of the FrameGraph. If two QParameter instances with the same name are specified in a QTechnique and a QRenderPass, the one in Technique overrides the one used in the QRenderPass.

When creating an QEffect that targets several versions of a graphics API, it is useful to create several QTechnique nodes each with a graphicsApiFilter set to match one of the targeted GL versions. At runtime, the Qt3D renderer will select the most appropriate QTechnique based on which graphics API versions are supported and (if specified) the QFilterKey nodes that satisfy a given QTechniqueFilter in the FrameGraph.

Note: When using OpenGL as the graphics API for rendering, Qt3D relies on the QSurfaceFormat returned by QSurfaceFormat::defaultFormat() at runtime to decide what is the most appropriate GL version available. If you need to customize the QSurfaceFormat, do not forget to apply it with QSurfaceFormat::setDefaultFormat(). Setting the QSurfaceFormat on the view will likely have no effect on Qt3D related rendering.

Note: QTechnique node can not be disabled.

 QTechnique *gl3Technique = new QTechnique();

 // Create the render passes
 QRenderPass *firstPass = new QRenderPass();
 QRenderPass *secondPass = new QRenderPass();

 // Add the passes to the technique
 gl3Technique->addRenderPass(firstPass);
 gl3Technique->addRenderPass(secondPass);

 // Set the targeted GL version for the technique
 gl3Technique->graphicsApiFilter()->setApi(QGraphicsApiFilter::OpenGL);
 gl3Technique->graphicsApiFilter()->setMajorVersion(3);
 gl3Technique->graphicsApiFilter()->setMinorVersion(1);
 gl3Technique->graphicsApiFilter()->setProfile(QGraphicsApiFilter::CoreProfile);

 // Create a FilterKey
 QFilterKey *filterKey = new QFilterKey();
 filterKey->setName(QStringLiteral("name"));
 fitlerKey->setValue(QStringLiteral("zFillPass"));

 // Add the FilterKey to the Technique
 gl3Technique->addFilterKey(filterKey);

 // Create a QParameter
 QParameter *colorParameter = new QParameter(QStringLiteral("color"), QColor::fromRgbF(0.0f, 0.0f, 1.0f, 1.0f));

 // Add parameter to technique
 gl3Technique->addParameter(colorParameter);