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. A QParameter defined on a QTechnique overrides parameter (of the same name) defined in QRenderPass, but are overridden by parameter in QRenderPassFilter, QTechniqueFilter, QMaterial and QEffect.

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.

 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);