Improved logic for CharacterBody collision recovery depth

Allows 2D character controller to work without applying gravity when
touching the ground (also more safely in 3D), and collision detection
is more flexible with different safe margin values.

Character body motion changes in 2D and 3D:
-Recovery only for depth > min contact depth to help with collision
detection consistency (rest info could be lost if recovery was too much)
-Adaptive min contact depth (based on margin) instead of space parameter

Extra CharacterBody changes:
-2D: apply changes made in 3D for stop on slope and floor snap that help
fixing some jittering cases
-3D: fix minor inconsistencies in stop on slope and floor snap logic

3 files changed, 1 insertions, 5 deletions

diff --git a/doc/classes/CharacterBody2D.xml b/doc/classes/CharacterBody2D.xml
index 882aa8bd71..6e8d7a2b15 100644
--- a/doc/classes/CharacterBody2D.xml
+++ b/doc/classes/CharacterBody2D.xml
@@ -133,7 +133,7 @@
 		<member name="floor_max_angle" type="float" setter="set_floor_max_angle" getter="get_floor_max_angle" default="0.785398">
 			Maximum angle (in radians) where a slope is still considered a floor (or a ceiling), rather than a wall, when calling [method move_and_slide]. The default value equals 45 degrees.
 		</member>
-		<member name="floor_snap_length" type="float" setter="set_floor_snap_length" getter="get_floor_snap_length" default="0.0">
+		<member name="floor_snap_length" type="float" setter="set_floor_snap_length" getter="get_floor_snap_length" default="1.0">
 			Sets a snapping distance. When set to a value different from [code]0.0[/code], the body is kept attached to slopes when calling [method move_and_slide]. The snapping vector is determined by the given distance along the opposite direction of the [member up_direction].
 			As long as the snapping vector is in contact with the ground and the body moves against `up_direction`, the body will remain attached to the surface. Snapping is not applied if the body moves along `up_direction`, so it will be able to detach from the ground when jumping.
 		</member>
diff --git a/doc/classes/PhysicsServer2D.xml b/doc/classes/PhysicsServer2D.xml
index 7e5d7ca704..b604503163 100644
--- a/doc/classes/PhysicsServer2D.xml
+++ b/doc/classes/PhysicsServer2D.xml
@@ -851,8 +851,6 @@
 		<constant name="SPACE_PARAM_CONSTRAINT_DEFAULT_BIAS" value="6" enum="SpaceParameter">
 			Constant to set/get the default solver bias for all physics constraints. A solver bias is a factor controlling how much two objects "rebound", after violating a constraint, to avoid leaving them in that state because of numerical imprecision.
 		</constant>
-		<constant name="SPACE_PARAM_TEST_MOTION_MIN_CONTACT_DEPTH" value="7" enum="SpaceParameter">
-		</constant>
 		<constant name="SHAPE_WORLD_BOUNDARY" value="0" enum="ShapeType">
 			This is the constant for creating world boundary shapes. A world boundary shape is an [i]infinite[/i] line with an origin point, and a normal. Thus, it can be used for front/behind checks.
 		</constant>
diff --git a/doc/classes/PhysicsServer3D.xml b/doc/classes/PhysicsServer3D.xml
index 9f48c36b62..30812845e2 100644
--- a/doc/classes/PhysicsServer3D.xml
+++ b/doc/classes/PhysicsServer3D.xml
@@ -1361,8 +1361,6 @@
 		<constant name="SPACE_PARAM_CONSTRAINT_DEFAULT_BIAS" value="7" enum="SpaceParameter">
 			Constant to set/get the default solver bias for all physics constraints. A solver bias is a factor controlling how much two objects "rebound", after violating a constraint, to avoid leaving them in that state because of numerical imprecision.
 		</constant>
-		<constant name="SPACE_PARAM_TEST_MOTION_MIN_CONTACT_DEPTH" value="8" enum="SpaceParameter">
-		</constant>
 		<constant name="BODY_AXIS_LINEAR_X" value="1" enum="BodyAxis">
 		</constant>
 		<constant name="BODY_AXIS_LINEAR_Y" value="2" enum="BodyAxis">