This functionality is available on Onshape's browser, iOS, and Android platforms.
The Onshape sketch editor has the ability to assign constraints to certain entities automatically. For example, create a line and hover one of the endpoints above the origin and a dotted line appears indicating a vertical inference between that endpoint and the origin.
When sketching, Onshape displays inferences for Horizontal and Vertical alignment between an entity and the origin and/or another entity. In some cases, inference only occurs when the cursor is moved near another entity to 'wake up' the inferencing between the two entities. Some commonly used wake up inferences are: horizontal, vertical, midpoint, parallel, and coincident.
- Create two lines with a perpendicular constraint between them.
- Move cursor near line until inferencing ‘wakes up’.
- Draw a line.
When sketching, Onshape indicates relationships with other sketch entities. In the illustration below, the bottom (blue) line is the one being drawn. When it is parallel to the other line it turns to a dotted line and the other is highlighted in orange to show that there is a relation present. (The parallel constraint icon is also visible in this example.)
To suppress automatic inferences, press the Shift key when mousing.
This video will go through inferences and how they can be used to facilitate applying constraints on a single entity or between entities on a sketch. An inference is an automatic way for Onshape to guide you by displaying constraints to the sketch entities. You can elect to use them or ignore them. There are two ways to use inference.
In the first example, we will go through inferencing on a single entity. We are on a sketch and have selected the front plane. Choose the Line tool from the toolbar. Draw a line straight down. Notice the yellow dashed line that appears on the entity and a vertical constraint is automatically applied.
For the second example, we will go through inference between sketch entities. We have a circle already on the sketch. Now, select the Line tool and hover over the center point of the circle. This will wake up automatic inference between the entities. Create a line from the center of the circle to the edge of the circle and notice how a coincident constraint is applied. To disable automatic inferencing, hold the shift key while clicking to finalize a sketch entity. Notice how a coincident constraint is not applied.
Automatic inferencing can also happen between two shapes. Here, we have a rectangle and I’ve selected the Circle tool. Notice how there is already a yellow line. This is indicating a parallel constraint between the rectangle and the circle I'm about to make. I could also make another circle that is at the midpoint of the rectangle and coincident with the rectangle. These are just some examples of different ways that you can use automatic inferencing.