QMultiSampleAntiAliasing Class

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;
 }