In SketchUp you can draw or move objects freely or in an axis direction.
Inference locking is telling SketchUp you want to focus in one specific direction.
You can inference lock to any of the axis directions,
or lock to any existing edge,
and you can quickly unlock and lock to another direction at any time.
To lock a direction you must find a direction first
then hold the Shift key down to lock it. Try drawing a line in the red direction
then hold the Shift key and you can see that the line visually thickens, showing that it's locked.
As long as you hold down the Shift key,
you will stay locked in the red direction. Release the shift key to release the lock,
and find another direction to lock to.
Remember it's important to find the direction first
To lock the green direction in
you must first be moving in the green direction then hold the Shift key down to lock in that direction.
This also works in a parallel direction.
Hover over an edge to be able to draw parallel to that edge.
When you see the purple color indicating that you're parallel
You can hold Shift down to lock in that direction.
In fact, you can even lock a direction before starting to draw an edge.
The principle is the same. We have to find a direction first before locking it.
Select the line tool. Then by hovering over this edge
you're effectively choosing that edge as your direction.
Hold down the Shift key while still hovering over the edge
then move your cursor away and it shows a dotted line
leading back to the edge indicating that you're locked to it.
Now as you draw, you're locked in a parallel direction.
Another way to lock is using the arrow keys.
The keys all correspond to an axis direction.
The up and down arrows correspond to the blue direction.
The left arrow is green. The right arrow is red.
Start moving an object in any direction
and press the right arrow key to lock in the red direction,
and it automatically locks that direction.
Press the up arrow and you are now locked in a blue direction.
To release the lock press the corresponding a row again.
This way of locking is very fast and easy,
however, it doesn't let you lock to edges that are not along the axis.
So it's good to know how to lock with both the arrow keys and the Shift key.
Now let's work through an example using inference locking.
We'll start with these two rectangles. One drawn in line with the axis.
The other in some arbitrary direction. let's find where these blocks would meet
together and draw the resulting mitre
start by drawing a line from this corner then press the left arrow key to lock
green direction
now you can move the cursor around a reference other geometry
however if you have room for this endpoint it lines up in a perpendicular
direction
which isn't what we need try moving to the edge itself
and now you can see that were lined up correctly click to finish that line
and draw the next line
now one up the other agents this time try hovering over this edge first
hold the Shift key down to lock it in click to start drying your line
as long as you're holding the Shift key we r lot to that edge
so we can then move around to find the inference we need
remember again it isn't the end point but the line
itself in this case
finish the edges and we have drawn the correct mitre to join these two shapes
so far we focus on locking two edges but in fact you can also lock to a surface
for example let's take the surface and rotated around so it isn't aligned in
any direction with the axis
using the online tool hover over the surface
and hold down the shift key walking to that surface now is you move away
there's a dotted line indicating your lock to the surface any
edges he draw will be co plainer to that surface
you will probably find
walking to a surface isn't is useful is walking two edges
when using the drawing tools
remember though that you can lock when using the move tool as well
and here's one case for locking to a surface is pretty useful
as you may have seen when using the move tool
is easy to move objects into the ground or into other objects
say we want to place the sand table against the wall
so we start moving it by this corner but trying to reference the corner of the
room causes problems
let's use an inference lock to solve the problem
for select the table so will be the object is moved
then using the move tool hover over the floor first
and hold the Shift key down to lock the floor surface now while holding SHIFT
click on the corner of the table to start moving it from that point
which allows you to then reference the corner of the room
walking to the floor keeps the table at exactly the right height
and it is easy to place the table somewhere along the wall be sure to
click and finished the move before releasing the shift key
this is a common mistake for new users
you must always finisher move or drawing tool before you release the shift key
or you will lose your lock
if you would like to practice inferencing inference locking more
look for the video on creating a refusing inferencing