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Unity Engine

G-buffer layout in the Deferred and Deferred+ rendering paths in URP

Understand how Unity stores material attributes in the geometry buffer (G-buffer) in the Deferred rendering path.
Read time 3 minutesLast updated a month ago
The following illustration shows the data structure for each pixel of the render targets that Unity uses in the G-buffer in the Deferred and Deferred+ rendering path.

Data structure of the render targets that Unity uses in the Deferred and Deferred+ rendering paths

Unity uses a forward render pass to render the following default shaders:
  • Complex Lit: The lighting model is too complex to fit into the G-buffer.
  • Baked Lit or Lit: There's no realtime lighting, so Unity renders the data into the Emissive/GI/Lighting field of the G-buffer. This is quicker than using a deferred render pass.

Albedo (sRGB)

This field contains the albedo color in 24-bit sRGB format.

MaterialFlags

This field is a bit field that contains material flags:
  • Bit 0, ReceiveShadowsOff: if set, the pixel does not receive dynamic shadows.
  • Bit 1, SpecularHighlightsOff: if set, the pixel does not receive specular highlights.
  • Bit 2, SubtractiveMixedLighting: if set, the pixel uses the Subtractive Lighting Mode.
  • Bit 3, SpecularSetup: if set, the material uses the specular workflow.
Bits 4 to 7 are reserved for future use.

Specular

This field contains the following 24-bit values:
  • Simple Lit material: RGB specular color stored in 24 bits.
  • Lit material with metallic workflow: Reflectivity stored in 8 bits. The other 16 bits aren't used.
  • Lit material with specular workflow: RGB specular color stored in 24 bits.

Occlusion

This field contains the baked occlusion value from baked lighting. For realtime lighting, Unity calculates the ambient occlusion value by combining the baked occlusion value with the screen space ambient occlusion (SSAO) value.

Normal

This field contains the world space normals encoded in 24 bits. For more information, refer to Enable accurate G-buffer normals in the Deferred rendering path.

Smoothness

This field stores the smoothness value for the Simple Lit and Lit materials.

Emissive/GI/Lighting

This render target contains the material emissive output and baked lighting. Unity fills this field during the G-buffer render pass. During the deferred shading pass, Unity stores lighting results in this render target.
The default format is 
B10G11R11_UFloatPack32
.
Unity uses 
R16G6B16A16_SFloat
if either of the following is true:
  • In the URP asset, Quality Settings >
    HDR

    ?

    is enabled but the build platform doesn't support HDR.
  • In the Player settings window, PreserveFramebufferAlpha is enabled.
If Unity can't use 
B10G11R11_UFloatPack32
or 
R16G6B16A16_SFloat
, it uses the default HDR format.

ShadowMask

Unity adds this render target to the G-buffer layout when you set the Lighting Mode to Subtractive or
Shadowmask

?

.

Rendering Layer Mask

Unity adds this render target to the G-buffer layout when you enable Rendering Layers.

Depth as Color

Unity adds this render target to the G-buffer layout when you enable Native Render Passes, and the platform supports them. Unity renders depth as a color into this render target. This render target has the following purpose:
  • Improves performance on Vulkan devices.
  • Lets Unity get the depth buffer on platforms that use the Metal graphics API, which doesn't allow fetching the depth from the DepthStencil buffer within the same render pass.
The format of this render target is 
GraphicsFormat.R32_SFloat
.

DepthStencil

Unity reserves the four highest bits of this render target for the material type. For more information, refer to URP ShaderLab Pass tags.
The format of this render target is 
D32F_S8
or 
D24S8
, depending on the platform.

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