Lazy Nezumi Pro Rulers

Along with its stabilization and scripting capabilities, Lazy Nezumi Pro offers some pretty useful rulers that will help with technical drawing. This guide will show you how to use them.

Ruler Parameters

When a ruler is active, guides will be displayed over your canvas. These are rendered on a transparent overlay window. You can control its opacity and other settings via Settings/Edit Overlay Settings. While you're there, be sure to enable Direct2D for improved performance (if you experience any lag, you may try a different adapter via the list, or try turning off Direct2D).

Most of the ruler modes have parameters that control how the ruler behaves. They can be controlled the following ways:

  • Via the parameter slider or numeric box in the UI;
  • via the on-screen control point graphics, while holding the control key;
  • via individual keyboard shortcuts, which can be configured via Settings/Edit Shortcuts/Ruler Shortcuts.

You'll also notice that all ruler modes have a common Accuracy parameter. When set to a value of 1, the line you draw will be fully projected onto the selected ruler. The closer this value gets to 0, the more of your original input gets mixed in, letting you add imperfections to make the lines look more natural. Set it to 0 if you don't want your line to snap to the ruler at all, but still wish to see the overlay guide. You can configure the Ruler Accuracy Off/Restore global shortcut to quickly toggle this parameter.

When using the rulers, be sure to disable any stabilizer or line smoothing feature in your art program, as this can interfere.


LNP Ellipse UI

This mode will help you draw ellipses and circles. It has the following parameters you can adjust:

  • Degree - The degree of the ellipse. Set it to 90° for a circle.
  • Rotation - Rotation of the ellipse minor axis (from the horizontal).
  • Connect Ends - When accuracy is lower than 1, checking this option will ensure that none of your original input gets mixed in towards the start and end of the ellipse, effectively helping you connect the ends neatly.
  • Radial Line - This enables the radial ruler connecting to the center. When enabled, you can toggle between the ellipse and the radial line by tapping Shift before drawing (this can be changed in the Shortcut settings, via the “Select Line” shortcut). While drawing, you can switch lines by pressing control.
  • Box Mode - When Radial Line and this are turned on and you switch lines while drawing, your pen will be clamped to an elliptical/circular section box defined by the angles and radial length of your first lines. If set to X-Symmetric or Y-Symmetric, the end angle will be determined when you start drawing, depending on which direction around the ellipse/circle you are going.

The ellipse center can be moved around by dragging its center point. The size of the ellipse is determined by your pen down position. It is currently not possible to lock the ellipse to a certain size. If you look at the minor and major axis, a portion of them will be orange. This indicates the size of the last drawn ellipse. Use these guides if you need to draw multiple ellipses of the same size at different locations, or disconnected portions of the same ellipse.

The Auto Fit button (or associated global shortcut) can help you find good parameters automatically. Simply press the button, then sketch an ellipse (it doesn't have to be complete), and LNP will try to find the best parameters that fit your sketch! You can then fine-tune via the interactive control points.

You can activate the interactive control points by holding the control key. You'll notice that the center point becomes yellow. In this mode, it slides along the minor or major axis. Hold shift while using the rotation handle to clamp to 5° increments.

LNP Ellipse Ruler Control Points

When the Box Mode parameter is active, the active span limits will be shown in orange on the ellipse and radial line.

LNP Ellipse Ruler Box Mode

When this ruler is active, you can use the following predefined input variables when scripting:

  • dn - Normalized distance around the circle/ellipse. This can be used to sync patterns that need to repeat exactly when going around more than once.
  • ew - The current ellipse width. This can be used to modulate pattern sizes based on the size of the ellipse you are drawing. The width is always greater or equal to the height.
  • eh - The current ellipse height.
  • er - The current ellipse rotation.
  • eca - The current angle of your pen position.

See the Circular Patterns and Isometric Circle Patterns script modes for examples on how to use these. The Misc - Gears preset uses the circular square wave mode to create perfect gear shapes.

LNP Ellipse Ruler + Circular Square Wave Script

Perspective Ellipse

When drawing circles and ellipses in perspective, it's always tricky to find the right center/degree/rotation for the projected ellipse. With this ruler, all you have to do is align the four corner control points with the projected square or rectangle within which you wish to draw circles or ellipses.

When you move your pen, the ellipse will be adjusted so that it passes through your current pen position, but keeps the original perspective projected center. This allows you to quickly draw perspective correct concentric circles or ellipses.

Concentric Perspective Circles

The entire quad can be moved by using the Move Center keyboard shortcut, or by holding the control key while dragging any of the corner control points.

The yellow edge control points have different behaviors depending on which key you hold while dragging them:

  • No key: slide only that edge.
  • Shift: slide that edge and its opposite in symmetry.
  • Control: slide the entire quad, preserving perspective proportions.
Arches Perspective Ellipse ruler

This ruler also has a radial line option and box modes that work the same way as for the Ellipse ruler.

Arches Perspective Ellipse Box Mode

Radial Lines

LNP Radial Lines UI

This mode will help you draw lines that radiate out from a center point. This is often used in illustration to give the impression of motion and dynamics.

It has one Curve parameter that will let you create curved radial lines. These are simple quadratic curves.

The center point can be moved around by dragging the control point. Holding the control key will also show the curve control point.

LNP Radial Lines Ruler Control Points

The script modes in the Radial Patterns can be used with this ruler. Here's the Radial Fade script mode in action. This script will automatically attenuate the pressure of your stroke as it approaches the center.

LNP Ellipse Radial Fade

Parallel Lines

LNP Parallel Lines UI

This mode will help you draw parallel lines. It has one angle parameter that lets you rotate the line.

You can also change the angle by using the control point while holding down the control key, or by holding space (rotate around current pen position) or shift (rotate around last pen up position).

While holding control, you can also adjust the unit distance between the measure points by sliding the yellow control point.

LNP Parallel Lines Ruler Control Points

Connected Lines

LNP Connected Lines UI

This mode is useful for constructing shapes from straight lines, where the start of each new line is connected to the previous line.

You can press shift to change the connection point between the start, center, and end of the previous line. While holding control, you can also change the measure point unit distance by sliding the yellow control point.

LNP Connected Lines Ruler Control Points LNP Connected Lines Ruler

Use the Stop at connection point option to prevent your line from overshooting past the connection point.

LNP Connected Lines Ruler

Isometric Perspective

LNP Isometric UI

Isometric projection is a method for visually representing three-dimensional objects in two dimensions in technical and engineering drawings. It is often used in game art.

This mode will help you draw isometric art. It has 3 rulers for which you can change the angles.

The Line Select Mode parameter determines which ruler is chosen when you draw:

  • Manual start & change: You have to manually choose which ruler to start drawing on by pressing the shift key. You can change lines while drawing by pressing the control key.
  • Auto start, manual change: The starting ruler will be chosen automatically based on the direction of the first few samples of your line. You can change directions while drawing by pressing the control key.
  • Auto start & change: Same as the previous option, but you can change lines while drawing without pressing control. This mode is great for fast 3d sketching.

When Box Mode is enabled, your pen position will be clamped to a 3d bounding box while you draw, helping you quickly close boxes without overshooting. The dimensions of the box are determined automatically one at a time as you first draw on each axis. The dimensions are reset when you lift the pen.

While not drawing, holding the control key will also display the angle control points, the measure point unit distance control point, and the freeze mode toggle control point.

LNP Isometric Ruler Control Points

Clicking on the Freeze Mode control point (or pressing the associated keyboard shortcut) will create a fixed frame of reference at your pen position. You can use this and the measure points to accurately subdivide sections.

Fisheye Perspective

LNP Fisheye UI

Whereas linear perspective projects straight 3d lines to straight 2d lines, fisheye perspective projects them to curved 2d lines. This perspective mode has a fixed field of view of 180°. Half of the world is effectively projected onto the view circle.

The view circle is controlled by its center point and View Radius parameter. Be sure to set the Image Zoom parameter to your current canvas zoom level. It is also recommended to draw a mark under the center in a separate layer, so you can realign it easily.

This mode does not let you change the line angles. You can choose between a horizontal line, a vertical line, and a line going to the view center.

Holding the control key will display the measure point unit distance control point, and the freeze mode toggle control point.

Clicking on the Freeze Mode control point (or pressing the associated keyboard shortcut) will create a fixed frame of reference at your pen position. Like with the Isometric, Vanishing Lines, and Linear Perspective rulers, you can use this and the measure points to accurately subdivide sections.

LNP Fisheye Perspective Measure Control Point

Vanishing Lines

LNP Vanishing Lines UI

With the Linear Perspective ruler, you can setup your perspective scene very accurately by specifying viewing parameters and 3d line angles.

But sometimes you have an existing scene where you don't know any of these parameters. As long as the scene is using a linear perspective projection (and not any type of curvilinear projection such as fisheye), the Vanishing Lines ruler will help you add perspective-correct elements to it.

This ruler gives you up to 6 vanishing points (VPs) to work with (although you probably don't want them all active at the same time). Each point it computed automatically by adjusting two control lines. Simply line up the control lines with edges that are parallel in the 3d scene (for example, the opposing edges of a wall). You'll now be able to draw lines that are 3d parallel to these edges.

Controls: To enter or exit VP setup mode, press control+shift, or click on one of the blue control points that appear while holding control. Press shift to cycle through the VPs. While in VP setup mode, you can adjust the position of each control line by moving either of its points. If you hold the control key while moving a point, both points will move together, allowing for convenient repositioning of the line.

Vanishing Lines workflow

Each vanishing line has its own independent measure point unit distance, which can be changed by sliding the yellow control point that appears while holding control while in Freeze Mode (which is toggled via the pink control point). You can then use the measure points to quickly figure out 3d distances, and cut sections into equal parts. In the following example, I extend the top block of a building, making it symmetric. Notice how the measure points have been aligned to give me information about the building's size.

Vanishing Lines ruler

This ruler will also help when you need to draw inclines, such as roofs and ramps, as shown in the following example.

Inclines with the Vanishing Lines ruler