[Bf-docboard-svn] bf-manual: [7707] trunk/blender_docs/manual: Update force field option descriptions and add a use case for Show Weight Contours.

[Alexander Gavrilov]

Revision: 7707
          https://developer.blender.org/rBM7707
Author:   angavrilov
Date:     2021-02-02 21:41:55 +0100 (Tue, 02 Feb 2021)
Log Message:
-----------
Update force field option descriptions and add a use case for Show Weight Contours.

Modified Paths:
--------------
    trunk/blender_docs/manual/editors/3dview/display/overlays.rst
    trunk/blender_docs/manual/physics/forces/force_fields/introduction.rst

Modified: trunk/blender_docs/manual/editors/3dview/display/overlays.rst
===================================================================
--- trunk/blender_docs/manual/editors/3dview/display/overlays.rst	2021-02-02 03:56:17 UTC (rev 7706)
+++ trunk/blender_docs/manual/editors/3dview/display/overlays.rst	2021-02-02 20:41:55 UTC (rev 7707)
@@ -294,6 +294,10 @@
 
 Show Weight Contours
    Show contour lines formed by points with the same interpolated weight.
+
+   This visualizes weight variations too small to be seen from colors and can be useful for judging
+   the smoothness and consistency of gradients, e.g. when using smoothing tools and brushes.
+
 Show Wire
    Use wireframe display in paint modes.
 

Modified: trunk/blender_docs/manual/physics/forces/force_fields/introduction.rst
===================================================================
--- trunk/blender_docs/manual/physics/forces/force_fields/introduction.rst	2021-02-02 03:56:17 UTC (rev 7706)
+++ trunk/blender_docs/manual/physics/forces/force_fields/introduction.rst	2021-02-02 20:41:55 UTC (rev 7707)
@@ -75,7 +75,7 @@
 
 Shape
    Sets the direction which is used to calculate the effector force.
-   For force fields from an empty object only *Point* and *Plane* shapes are available,
+   For force fields from an empty object only *Point*, *Line* and *Plane* shapes are available,
    as for a field from a 3D object there are additional *Surface* and *Every Point* options,
    and *Curve* for a field from a curve.
 
@@ -82,8 +82,10 @@
    Point
       Point with omni-directional influence.
       Uses the object origin as the effector point.
+   Line
+      The force only acts in the local XY plane, using the Z axis line as the effector.
    Plane
-      Influence only in the local Z direction.
+      The force only acts in the local Z direction, using the XY axis plane as the effector.
    Surface
       The force field acts on a 3D object's surface.
       In this case, the Z axis is the surface normal.
@@ -99,10 +101,12 @@
    allowing you to scale up and down the scene, keeping the same effects.
 
 Flow
-   If non-zero, the effective force depends on the particle velocity.
-   The value defines how quickly the effector force (acceleration)
-   will be converted into the constant "air flow" velocity.
+   If non-zero, this adds a drag force proportional and opposite to the point velocity.
 
+   This effectively re-interprets the force field so that the *Strength* to *Flow* ratio
+   at a certain point defines the velocity of an "air flow" field, and objects are
+   encouraged to follow the flow by the resistance caused by the *Flow* drag force.
+
 Noise Amount
    Adds noise to the strength of the force.
 
@@ -111,10 +115,13 @@
 
 Affect
    Location
-      Influence the location of particles.
+      Influence the location of particles and other physics entities.
    Rotation
-      Influence the rotation of particles.
+      Influence the rotation of particles with :doc:`Dynamic Rotation </physics/particles/emitter/rotation>`.
+      The option is not relevant for other types of physics systems.
 
+   Disabling both options completely deactivates the force field.
+
 Absorption
    Force gets absorbed by collision objects.