QRenderPass Class

Detailed Description

A Qt3DRender::QRenderPass specifies a single rendering pass - an instance of shader program execution - used by Qt3DRender::QTechnique. Render pass consists of a Qt3DRender::QShaderProgram and a list of Qt3DRender::QFilterKey objects, a list of Qt3DRender::QRenderState objects and a list of Qt3DRender::QParameter objects.

QRenderPass executes the QShaderProgram using the given QRenderState and QParameter nodes when at least one of QFilterKey nodes being referenced matches any of the QFilterKey nodes in QRenderPassFilter or when no QFilterKey nodes are specified and no QRenderPassFilter is present in the FrameGraph.

If the QRenderPass defines a QParameter, it will be overridden by a QParameter with the same name if it exists in any of the QTechnique, QEffect, QMaterial, QTechniqueFilter, QRenderPassFilter associated with the pass at runtime. This still can be useful to define sane default values.

At render time, for each leaf node of the FrameGraph a base render state is recorded by accumulating states defined by all QRenderStateSet nodes in the FrameGraph branch. Each QRenderPass can overload this base render state by specifying its own QRenderState nodes.

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

 // Create shader program
 QShaderProgram *glShader = new QShaderProgram();

 // Set the shader on the render pass
 pass->setShaderProgram(glShader);

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

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

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

 // Add parameter to pass
 pass->addParameter(colorParameter);

 // Create a QRenderState
 QDepthTest *depthTest = new QDepthTest();

 // Add the render state to the pass
 pass->addRenderState(depthTest);