[Bf-docboard-svn] bf-manual: [7506] trunk/blender_docs/manual/render/cycles: Cycles: move light path info out of introduction page

[Brecht Van Lommel]

Revision: 7506
          https://developer.blender.org/rBM7506
Author:   brecht
Date:     2020-12-21 19:36:37 +0100 (Mon, 21 Dec 2020)
Log Message:
-----------
Cycles: move light path info out of introduction page

This reverts part of r5383, it makes little sense to put detailed information
about one specific aspect of the renderer on the introduction page. If it was
a general introduction to path tracing it may make sense, but that's not what
this text is.

Revision Links:
--------------
    https://developer.blender.org/rBM5383

Modified Paths:
--------------
    trunk/blender_docs/manual/render/cycles/introduction.rst
    trunk/blender_docs/manual/render/cycles/render_settings/light_paths.rst

Modified: trunk/blender_docs/manual/render/cycles/introduction.rst
===================================================================
--- trunk/blender_docs/manual/render/cycles/introduction.rst	2020-12-21 02:53:59 UTC (rev 7505)
+++ trunk/blender_docs/manual/render/cycles/introduction.rst	2020-12-21 18:36:37 UTC (rev 7506)
@@ -17,49 +17,3 @@
 
    The `Cycles website <https://www.cycles-renderer.org/>`__ with more information and a gallery.
 
-
-.. todo: expand to describe how ray tracing works.
-
-Light Rays
-==========
-
-Ray types can be divided into four categories:
-
-#. Camera: the ray comes straight from the camera.
-#. Reflection: the ray is generated by a reflection off a surface.
-#. Transmission: the ray is generated by a transmission through a surface.
-#. Shadow: the ray is used for (transparent) shadows.
-
-Reflection and transmission rays can further have these properties:
-
-- Diffuse: the ray is generated by a diffuse reflection or transmission (translucency).
-- Glossy: the ray is generated by a glossy specular reflection or transmission.
-- Singular: the ray is generated by a perfectly sharp reflection or transmission.
-
-The Light Path node can be used to find out the type of ray the shading is being computed for.
-
-.. figure:: /images/render_cycles_introduction_rays.svg
-   :align: center
-
-.. seealso::
-
-   The object :ref:`ray visibility <cycles-ray-visibility>` settings.
-
-
-.. _render-cycles-light-paths-transparency:
-
-Transparency Rays
------------------
-
-The transparent :abbr:`BSDF (Bidirectional scattering distribution function)` shader is given
-special treatment. When a ray passes through it, light passes straight on,
-as if there was no geometry there.
-The ray type does not change when passing through a transparent BSDF.
-
-Alpha pass output is also different for the transparent BSDF.
-Other transmission BSDFs are considered opaque,
-because they change the light direction. As such they cannot be used for
-alpha-over compositing, while this is possible with the transparent BSDF.
-
-Note that, while semantically the ray passes through as if no geometry was hit,
-rendering performance is affected as each transparency step requires executing the shader and tracing a ray.

Modified: trunk/blender_docs/manual/render/cycles/render_settings/light_paths.rst
===================================================================
--- trunk/blender_docs/manual/render/cycles/render_settings/light_paths.rst	2020-12-21 02:53:59 UTC (rev 7505)
+++ trunk/blender_docs/manual/render/cycles/render_settings/light_paths.rst	2020-12-21 18:36:37 UTC (rev 7506)
@@ -9,12 +9,34 @@
 
    :Panel:     :menuselection:`Render --> Light Paths`
 
+Ray Types
+=========
 
-.. _cycles-bounces:
+Ray types can be divided into four categories:
 
-Max Bounces
------------
+#. Camera: the ray comes straight from the camera.
+#. Reflection: the ray is generated by a reflection off a surface.
+#. Transmission: the ray is generated by a transmission through a surface.
+#. Shadow: the ray is used for (transparent) shadows.
 
+Reflection and transmission rays can further have these properties:
+
+- Diffuse: the ray is generated by a diffuse reflection or transmission (translucency).
+- Glossy: the ray is generated by a glossy specular reflection or transmission.
+- Singular: the ray is generated by a perfectly sharp reflection or transmission.
+
+The Light Path node can be used to find out the type of ray the shading is being computed for.
+
+.. figure:: /images/render_cycles_introduction_rays.svg
+   :align: center
+
+.. seealso::
+
+   The object :ref:`ray visibility <cycles-ray-visibility>` settings.
+
+Bounce Control
+==============
+
 The maximum number of light bounces can be controlled manually.
 While ideally this should be infinite,
 in practice a smaller number of bounces may be sufficient,
@@ -27,6 +49,32 @@
 they are expected to contribute less light to the image.
 This will still converge to the same image, but renders faster while possibly being noisier.
 
+.. _render-cycles-light-paths-transparency:
+
+Transparency
+============
+
+The transparent :abbr:`BSDF (Bidirectional scattering distribution function)` shader is given
+special treatment. When a ray passes through it, light passes straight on,
+as if there was no geometry there.
+The ray type does not change when passing through a transparent BSDF.
+
+Alpha pass output is also different for the transparent BSDF.
+Other transmission BSDFs are considered opaque,
+because they change the light direction. As such they cannot be used for
+alpha-over compositing, while this is possible with the transparent BSDF.
+
+Note that, while semantically the ray passes through as if no geometry was hit,
+rendering performance is affected as each transparency step requires executing the shader and tracing a ray.
+
+Settings
+========
+
+Max Bounces
+-----------
+
+.. _cycles-bounces:
+
 Total
    Maximum number of light bounces. For best quality, this should be set to the maximum.
    However, in practice, it may be good to set it to lower values for faster rendering.