Hatching

A Hatch Hatch fills a closed area with a pattern. You do not draw the pattern lines yourself: you click inside the area, and LiberoDraft traces the surrounding edges, closes the boundary from them, leaves islands clear and fills in the pattern. A hatch is an object of its own next to geometry and dimensions — it has a pattern, a color, a layer and a Z level, and it remembers the point from which its area was searched.

This page explains the connections. Step-by-step instructions are under How-to, the commands under Hatch and Hatch settings, the fields under Hatch Settings dialog, the messages under Hatch messages.

Area search and seed point#

The point you click is the Seed point. Starting there, the program collects the edges in the vicinity, merges end points that coincide within the Tolerance into nodes and looks for the closed loop that encloses the seed point most tightly. Crossing edges are split at their intersections; dead ends that connect to nothing are dropped. If the drawing contains Blocks, the search starts in a box around the click point and widens it until the boundary found no longer touches the box — the result is the same as a search over the whole drawing, only faster.

Eligible as boundary:

• Lines , arcs , circles , rectangles , polylines , splines and ellipses .
• Elements inside blocks: blocks are resolved for the search, nested ones too. You do not need to explode a block to hatch an area inside or next to it.
• Only visible elements on visible layers. Whatever is hidden does not bound an area.

Not counted as boundary:

• Small circles up to the radius in the field Point markers r ≤ — they are treated as Point markers (construction or position marks) and are not traced. With 0 every circle counts.
• Dashed, dotted and dash-dot lines as soon as Only solid lines as boundary is switched on — even when the line type is inherited from the layer. Center lines and construction lines then do not disturb the search.
• Texts, dimensions, images, leaders and other annotations.

Visible area only#

Visible area only (faster) is switched on by default. The search then considers only elements within the current view (plus a small margin). On large drawings this makes boundary detection faster by orders of magnitude.

The option also affects updating: hatches outside the view are not recalculated, and a hatch whose boundary can no longer be found keeps its old outline — after all, the boundary might merely lie outside the view.

Islands#

Closed shapes inside the boundary are Islands and stay clear as long as Exclude islands is switched on (factory setting). The program recognizes as island:

• self-closed elements — circles, rectangles, closed polylines, closed splines and ellipses;
• closed loops made of several elements, such as a slot of two lines and two arcs or a kidney shape.

After creation the status bar reports the number of islands found, for example Hatch created: ANSI31 (5 islands). An island must lie inside the boundary with its centroid and most of its points; a shape that forms the boundary itself does not become an island.

Patterns#

You choose the Pattern in the Pattern: field of the dialog. Each pattern is a definition of type, angle, spacing, color, line width and line type; changing these fields changes the definition — it then applies to all new hatches with this pattern and is saved with the program settings. Existing hatches keep their values; you change them in the Properties panel.

With DOPPEL and DREIFACH the dialog additionally shows the field Package spacing: — the spacing of the two or three lines within one package. For the other patterns the field is hidden. The pattern names are generic, industry-standard designations without license obligations.

Angle, spacing and origin#

The angle rotates the whole pattern; 45° is the usual factory setting, 135° gives the opposite slant for a second part in a section, 0° horizontal and 90° vertical lines. The spacing is the distance between adjacent pattern lines. Smaller values give a denser picture.

The spacing applies in the units of the space the hatch lives in: in model space in drawing units (model millimetres), in a viewport in millimetres on paper — there it is not scaled with the viewport scale, because hatch density is a property of the sheet, not of the part.

The Origin (Origin X: and Origin Y:) is the reference point of the line grid. All hatches with the same angle, the same spacing and the same origin lie on the same grid — two adjacent areas then merge seamlessly as if they were one. The factory origin is the world origin 0/0. In the dialog it applies drawing-wide; in the Properties panel you can give a single hatch its own origin (empty = drawing-wide default) to offset it deliberately against its neighbours.

Color, line width, opacity, layer and Z level#

You show or hide all hatches together in the Layer palette via the system row Hatches; in a viewport, hatches can additionally be hidden per viewport.

Selecting, moving, deleting#

In the Select tool, click inside the hatched area (not inside an island) to select the hatch. Geometry and dimensions under the pointer take precedence, images rank behind the hatch. The selected hatch is tinted bluish, its boundary and island outlines are highlighted, and the Properties panel shows its values. When the pointer hovers over a hatch only its boundary lights up. The rubber band and the element list select hatches as well.

A selected hatch shows its seed point as a black square:

• Drag the square into another chamber and the area is searched there anew: the hatch moves.
• Hold Ctrl while releasing and the hatch stays where it is while a new hatch with the same settings is created at the drop point. This is the fastest way to fill several similar areas.
• If there is no closed area at the drop point, the point jumps back.

Del deletes selected hatches. Ctrl + C and Ctrl + V copy hatches together with the elements they lie in. When a block is made from elements with a hatch, the hatch moves into the block; a hidden block takes its hatches with it.

With Pick up [J] in the header bar you adopt pattern, layer and opacity of an existing hatch as defaults for the next hatches: switch pick-up on, click into the hatch.

Updating after geometry changes#

An automatic hatch remembers its seed point, not the finished boundary. If you change the surrounding geometry — move, stretch, trim, add a hole — the program searches the area again from the seed point, and the hatch grows or shrinks with it. A newly drawn line right across a hatch splits it: the hatch stays on the side of the seed point.

Special cases:

• If you move an island over the seed point, the island would be the nearest closed area around the point. The program recognizes this because the new boundary lies entirely inside the old one and is much smaller, and continues the search from a substitute point in the old area — the hatch stays on the area instead of jumping into the hole.
• If the boundary is no longer closed, the hatch is removed — unless Visible area only (faster) is on: then it keeps its old outline, because the missing boundary might lie outside the view.
• Manual hatches are not updated; their outline is a snapshot.
• Through-hatches are updated as soon as the sheet is needed (display, print, DXF); editing in model space costs nothing.

Manual area definition#

If the automatic search misses an area or an island, you define the boundary yourself: Area definition: Manual in the dialog. The snap mode switches to FREE; you click the boundary elements one by one — crossing elements too, the program uses the matching sub-segments. As soon as an area closes it is tinted semi-transparently in the pattern color; further loops inside become islands and are outlined with a dashed line. A second click on an element removes it from the selection again.

Enter or the Hatch (Enter) button creates the hatch; Esc or Cancel (ESC) discards the selection. The mode then stays on Manual so you can choose the next area right away; Automatic ends it. A manual hatch shows no seed-point square and is not updated after geometry changes.

In paper space the boundary elements may also come from the model: click model geometry through a viewport and a manual through-hatch is created. An outline always comes from one space — the first hit decides.

Hatching in a viewport#

In paper space you hatch through a viewport: with the Hatch tool, click into an area that is visible in the viewport. The program first checks whether a closed area of sheet geometry lies around the click — a rectangle you drew on the sheet above the viewport — and hatches that. If the sheet area encloses the whole viewport (a drawing frame), the search reaches through into the model. Such a Through-hatch keeps its boundary in model coordinates and shows the projected version on the sheet.

• The spacing applies in paper mm and is not scaled with the viewport scale.
• When the model changes, the boundary is updated as soon as the sheet is displayed, printed or exported.
• When you click a through-hatch, the status bar points out that the hatch and not the viewport was selected; select the viewport via its frame.
• The seed point can only be moved within the viewport; Ctrl creates a copy as in the model.
• If the viewport is deleted, the hatch can no longer be updated.

Printing and DXF#

When printing, hatch lines have their own line width in millimetres — field Hatches: in the Line widths (mm) section of the print dialog, factory 0.1 mm. Hatches are usually printed thinner than the geometry (0.1 to 0.25 mm).

On DXF export you choose in the options dialog how hatches are written: as a block (one object, exact copy) or as a hatch object (smaller, editable in the target CAD) — the native HATCH object whose pattern can be changed in the target CAD.

Known limits#

• A pocket open towards the outer edge cannot be distinguished geometrically from a real gap in the boundary. The hatch keeps following its seed point; define the boundary manually if needed.
• The boundary must be closed within the tolerance. If an area stays empty, the boundary is usually open at a corner — zoom in on the corners and check the end points with the Endpoint snap mode.
• With Visible area only (faster) the whole area must be in view.
• Elements in blocks can serve as boundary, but the hatch itself lies outside the block. If the hatch is to belong to the block, create it in the block editor or build the block from elements and hatch together.