Graphics Reference
In-Depth Information
Incorporating multisample anti-aliasing
One of the problems with classic deferred rendering is that to support the built-in hardware
anti-aliasing, we must implement some extra shader code to correctly sample from the MSAA
G-Buffer. More recent improvements in Direct3D have made this problem easy to solve by using
the
SV_SampleIndex
and
SV_Coverage
pixel shader system-value semantics to run the
shader for each sample and to determine which samples are covered by the current fragment.
Getting ready
It is necessary that all render targets are created with multisampling enabled. This includes
the render targets of the G-Buffer, the depth buffer, and also the light accumulation buffer
of the light renderer. Our implementations of the
GBuffer
and
LightRenderer
classes
already support multisampling provided we pass in the correct sample description to the
GBuffer
constructor, for example,
new SampleDescription(4, 0)
.
Our existing
ScreenAlignedQuadRenderer
must be modified to use the
multisampling pixel shader found in the
There's more…
section of
Implementing a
screen-aligned quad renderer
. A good way to organize this would be to check if the first
ScreenAlignedQuadRenderer.ShaderResources
SRV has a
ShaderResourceView.
Description.Dimension
of
SharpDX.Direct3D.ShaderResourceViewDimension.
Texture2DMultisampled
or not and choose the default pixel shader accordingly. This will
allow us to continue to use the same class when MSAA is on or off.
Be sure to have the Direct3D debug layer active during development. This provides useful
information to help address any incorrect configuration of resources.
How to do it…
We'll begin by updating our existing HLSL code to read the G-Buffer. We'll then update each
of the
LightRenderer
pixel shaders.
1.
First we need to use the multisampled textures of the G-Buffer by changing
Texture2D
to
Texture2DMS
, as shown in the following HLSL snippet.
Texture2DMS<float4> Texture0 : register(t0);
Texture2DMS<uint> Texture1 : register(t1);
Texture2DMS<float4> Texture2 : register(t2);
Texture2DMS<float> TextureDepth : register(t3);
Unlike the
Texture2D
resource, the
Texture2DMS
resource requires a
<data_type>
to be specified, for example,
Texture2DMS<float4>
