Sketch Inferencing

Sketch Inferencing

While you are in the process of creating a new entity, your active Sketch Creation command picks up certain inferences to aid you in creating your entity more accurately.

Introduction

While you are in the process of creating a new entity, your active Sketch Creation command picks up certain inferences to aid you in creating your entity more accurately. For example, you can precisely connect one line to another. Inferences may also be detected when editing Sketch entities.

Note: Some inferences produce temporary constraints that are only available when creating a particular entity. They are not persisted and cannot be added, removed or changed. See Sketch Constraints on page 169 for more information.

Some types of inferences are dependent on “touching” other Sketch entities with your mouse when in the middle of creating a new Sketch entity. For example, if you are moving your mouse when creating a line, and move it over a point or another line, the command remembers that you “touched” those entities and they now become reference entities for your currently active Sketch command. Touching a point or curve itself results in an inference.

Here is a list of inferences that are picked up and displayed to you through some graphical symbol. The number in parenthesis next to the inference name indicates the priority given to that inference, with 1 being the highest priority.

Geometry Inferences

Geometry inferences are displayed when your mouse is over some key geometry points.

■ Coincident Point Inference (1):

Sketch InferencingIf your cursor touches an existing Sketch point, you see a red square symbol. If the point happens to be the center of a circle or circular arc, then you see a red circle instead of a red square. If you click your mouse when you see this inference, your new point is guaranteed to coincide with the inferred point.

■ Point On Curve Inference(2):

Sketch InferencingThe red X symbol on any curve indicates that your cursor is touching a curve. If you click your mouse when you see this inference, then your new point is guaranteed to lie on the curve.

■ Midpoint Inference (5):

Sketch InferencingIf your cursor touches the midpoint of a straight line, you see a red triangle symbol indicating the midpoint. If the line has multiple segments, as in the following image, you do not see this inference.

Sketch Inferencing■ Sketch Grid Point Inference (6):

Sketch InferencingIf your cursor touches Sketch Grid snap point (on the visible Grid or the infinite Grid) you see a red square symbol. To learn more about Grid snapping, see the Sketch Grid on page 138 page.

Constraint Inferences

Constraint inferences are displayed based on your creation action. These inferences produce temporary constraints that affect how your entity is created. Some of these constraints is also inferred when you are editing a Sketch entity. See Sketch Constraints on page 169 for more information:

■ Tangent Constraint Inference (3):

Sketch InferencingConsider a situation in which you have a circle (or circular arc) drawn on your Sketch Plane. You now start drawing a line. If the first point on your line lies on the circle (use the Point-On-Curve inference to achieve this) and you drag/move the mouse in a direction roughly tangential to the circle, a Tangent constraint is inferred. You see a red circle symbol with a red line drawn tangent to it.

If you actually clicked the point on the circle before moving your mouse, your first point is fixed and you only infer this constraint when you move your mouse in a direction roughly tangential to the circle at your picked point.

However, if you pressed your mouse left button on the circle (without releasing it) and dragged the mouse in a direction tangential to the circle, your first point is not fixed. You can drag the mouse in any direction and your line adjusts to remain tangential to the circle. Releasing the mouse will define both points of your line simultaneously. This behavior is not limited by the bounds of an arc – it will exist for the entire logical circle that the arc is a part of.

■ Perpendicular Constraint Inference (3):

Sketch InferencingThis is very similar to the Tangent Constraint, except that it is inferred when you move/drag in a direction perpendicular to the circle or circular arc.

■ Horizontal Constraint Inference (4):

Sketch InferencingA horizontal constraint is inferred if you are drawing a line and drag your mouse such that the line is parallel to the X-axis of the Sketch Plane. It is indicated by a horizontal red line symbol.

Sketch InferencingAnother kind of horizontal constraint can be inferred by “touching” a point and moving the mouse in a horizontal direction. You will see a white line stretching from the “touched” (referenced) point to your current mouse position. This means that the point that your command is in the process of defining is constrained to have the same X-axis value as your “touched” point.

■ Vertical Constraint Inference (4):

Sketch InferencingA vertical constraint is inferred if you are drawing a line and drag your mouse such that the line is parallel to the Y-axis of the Sketch Plane. It is indicated by a vertical red line symbol.

Sketch InferencingAnother kind of vertical constraint can be inferred by “touching” a point and moving the mouse in a vertical direction. You will see a white line stretching from the “touched” (referenced) point to your current mouse position. This means that the point that your command is in the process of defining is constrained to have the same Y-axis value as your “touched” point.

■ Parallel Constraint Inference (4)

Sketch InferencingA parallel constrained is inferred when you “touch” a line that does not share endpoints with the line you are currently trying to create, and then moving your mouse in a direction roughly parallel to that line. Your line will be adjusted to be parallel to the “touched” (referenced) line and you will see a red horizontal line symbol on both the line being created and the “touched” line.

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