[Bf-docboard-svn] bf-manual: [8934] branches/blender-3.1-release/blender_docs/manual/render: Document the trick using Bump node to make a group input default to normal.

[Alexander Gavrilov]

Revision: 8934
          https://developer.blender.org/rBM8934
Author:   angavrilov
Date:     2022-02-08 13:22:47 +0100 (Tue, 08 Feb 2022)
Log Message:
-----------
Document the trick using Bump node to make a group input default to normal.

Modified Paths:
--------------
    branches/blender-3.1-release/blender_docs/manual/render/cycles/optimizations/nodes.rst
    branches/blender-3.1-release/blender_docs/manual/render/shader_nodes/vector/bump.rst

Modified: branches/blender-3.1-release/blender_docs/manual/render/cycles/optimizations/nodes.rst
===================================================================
--- branches/blender-3.1-release/blender_docs/manual/render/cycles/optimizations/nodes.rst	2022-02-07 17:44:30 UTC (rev 8933)
+++ branches/blender-3.1-release/blender_docs/manual/render/cycles/optimizations/nodes.rst	2022-02-08 12:22:47 UTC (rev 8934)
@@ -36,7 +36,9 @@
   Invert, RGB Curves and Vector Curves nodes with known zero Factor.
 - Eliminate Emission and Background shader nodes that do not emit any light,
   and Add Shader nodes with one or both input arguments missing.
-- Eliminate Bump with constant Height input, using its Normal input or Geometry Normal instead.
+- Eliminate :doc:`Bump </render/shader_nodes/vector/bump>` with constant Height input, using its Normal input or
+  Geometry Normal instead. This is useful for implementing node group inputs that default to normal via routing
+  through a no-op Bump before doing math.
 - Combine multiple copies of the same node with the same inputs into only one instance.
 
 Finally, any nodes that end up not connected either directly or indirectly to the Output node are removed.

Modified: branches/blender-3.1-release/blender_docs/manual/render/shader_nodes/vector/bump.rst
===================================================================
--- branches/blender-3.1-release/blender_docs/manual/render/shader_nodes/vector/bump.rst	2022-02-07 17:44:30 UTC (rev 8933)
+++ branches/blender-3.1-release/blender_docs/manual/render/shader_nodes/vector/bump.rst	2022-02-08 12:22:47 UTC (rev 8934)
@@ -40,6 +40,10 @@
 Normal
    Standard normal output.
 
+.. tip::
+   If the *Height* input is not connected, the node becomes a :doc:`no-op </render/cycles/optimizations/nodes>`
+   that outputs its *Normal* input as is, or defaults to the geometry normal if not connected. Routing a node
+   group input via a no-op Bump node before doing math effectively makes it default to normal.
 
 Examples
 ========