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QMultiSampleAntiAliasing Class

(Qt3DRender::QMultiSampleAntiAliasing)

Enable multisample antialiasing. More...

Header: #include <QMultiSampleAntiAliasing>
qmake: QT += 3drender
Since: Qt 5.7
Instantiated By: MultiSampleAntiAliasing
Inherits: Qt3DRender::QRenderState

This class was introduced in Qt 5.7.

Public Functions

QMultiSampleAntiAliasing(Qt3DCore::QNode *parent = nullptr)

Detailed Description

A Qt3DRender::QMultiSampleAntiAliasing class enables multisample antialiasing.

It can be added to a QRenderPass by calling QRenderPass::addRenderState():

QRenderPass *renderPass = new QRenderPass();

QMultiSampleAntiAliasing *msaa = new QMultiSampleAntiAliasing();
renderPass->addRenderState(msaa);

Or a QRenderStateSet by calling QRenderStateSet::addRenderState():

QRenderStateSet *renderStateSet = new QRenderStateSet();

QMultiSampleAntiAliasing *msaa = new QMultiSampleAntiAliasing();
renderStateSet->addRenderState(msaa);

For multisampling to take effect, the render target must have been allocated with multisampling enabled:

QTexture2DMultisample *colorTex = new QTexture2DMultisample;
colorTex->setFormat(QAbstractTexture::RGBA8_UNorm);
colorTex->setWidth(1024);
colorTex->setHeight(1024);

QRenderTargetOutput *color = new QRenderTargetOutput;
color->setAttachmentPoint(QRenderTargetOutput::Color0);
color->setTexture(colorTex);

QTexture2DMultisample *depthStencilTex = new QTexture2DMultisample;
depthStencilTex->setFormat(QAbstractTexture::RGBA8_UNorm);
depthStencilTex->setWidth(1024);
depthStencilTex->setHeight(1024);

QRenderTargetOutput *depthStencil = new QRenderTargetOutput;
depthStencil->setAttachmentPoint(QRenderTargetOutput::DepthStencil);
depthStencil->setTexture(depthStencilTex);

Qt3DRender::QRenderTarget *renderTarget = new Qt3DRender::QRenderTarget;
renderTarget->addOutput(color);
renderTarget->addOutput(depthStencil);

Further, the shader code must use multisampling sampler types and texelFetch() instead of texture().

For example, if you have code like

#version 150

uniform sampler2D colorTexture;
in vec2 texCoord;
out vec4 fragColor;

void main()
{
    fragColor = texture(colorTexture, texCoord);
}

you can rewrite it as

#version 150

uniform sampler2DMS colorTexture;
in vec2 texCoord;
out vec4 fragColor;

void main()
{
    ivec2 tc = ivec2(floor(textureSize(colorTexture) * texCoord));
    vec4 c = texelFetch(colorTexture, tc, 0) +
                texelFetch(colorTexture, tc, 1) +
                texelFetch(colorTexture, tc, 2) +
                texelFetch(colorTexture, tc, 3);
    fragColor = c / 4.0;
}

Note: When using OpenGL as the graphics API, glEnable(GL_MULTISAMPLE) will be called if QMultiSampleAntiAliasing has been added to the render states.

Member Function Documentation

QMultiSampleAntiAliasing::QMultiSampleAntiAliasing(Qt3DCore::QNode *parent = nullptr)

The constructor creates a new QMultiSampleAntiAliasing::QMultiSampleAntiAliasing instance with the specified parent.

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