The question "Shader created through the right-click menu under URP does not display any content" diverges, which extends the discussion of URP DepthPrepass.
Causes of the above problems
In the URP default pipeline, before rendering opaque objects, if one of the following situations occurs before Execute deep write Pass:
- yes
RenderFeature need Depth Texture / Normal Texture
- Camera selected
DepthTexture (Forced opening or Pipeline Asset check DepthTexture)
DepthPrimingMode && Forward Rendering && RenderType Base && CameraType != Reflection
Unity calls this process DepthPrepass.
Next, when rendering opaque objects:
- Not open
Depth Priming Mode ：
- If there is no special statement, use
ZTest LessEqual Elimination of slice elements by means of
- Not used
Depth Texture
- open
Depth Priming Mode ：
- Default Use
ZTest Equal , combined Depth Texture To eliminate slice elements
- Optimization of Overdraw for opaque queues
If the shader of an opaque object does not contain the Pass specified by DepthPrepass, Prepass will not write the depth of the current object.
Since there is no write depth, DepthPrimingMode The depth of the lower slice element is always not equal to the depth map, so the slice element is naturally eliminated.
The new URP is checked by default DepthPrimingMode , so the shader file created by right clicking does not display anything.
Specified Pass and calling time
In the URP default pipeline, two sets of passes are hard coded using the Pass Tag name:
- DepthOnlyPass:
DepthOnly
- DepthNormalOnlyPass:
DepthNormals / DepthNormalsOnly
In the default pipeline, the logic for selecting DepthOnlyPass or DepthNormalOnlyPass is as follows:
if(requiresDepthPrepass) { if(renderPassInputs.requiresNormalsTexture) { if(this.actualRenderingMode == RenderingMode. Deferred) { //Other contents are omitted m_DepthNormalPrepass.Setup(xxx); }else { m_DepthNormalPrepass.Setup(xxx); } EnqueuePass(m_DepthNormalPrepass); }else { if(this.actualRenderingMode != RenderingMode.Deferred) { m_DepthPrepass.Setup(xxx); EnqueuePass(m_DepthPrepass); } } }
According to the URP source code, when the RenderFeature (such as SSAO) has Normal enabled, DepthNormalOnlyPass will be executed, otherwise DepthOnlyPass will be executed.
What's the usage?
As mentioned above, this is to optimize OverDraw of opaque queues.
Although we expect the opaque queue to render from front to back, this sort is a rough sort of mesh, not a sort of image or slice (the CPU side cannot process the image or slice by pixel). OverDraw always exists.
Using ZTest Equal in combination with depth maps, the overdraw of opaque queues will be significantly optimized.
Solution to initial problems
It doesn't matter
turn off Depth Priming Mode , anyway Depth Priming Mode + MSAA The profit on TBR GPU is not necessarily large.
A safe approach
Opaque objects should complete the relevant Pass honestly. Depth Pass is only for writing depth, and the content should not be too complex.
If there is no vertex or slice displacement, just copy the Pass of URP Lit.
