### Pattern Definition Format

The pattern file is a text file, saved with a '.pat' extension.Definition of units (important for metric):

;%UNITS=MM

Each pattern definition has an * prefixed header : a title and description separated by a comma

*Stretcher 400x200, 400mm x 200mm stretcher bond

Drafting or Model definition:

;%TYPE=MODEL

Each line repeat (in the pattern) is described in one row of text, with comma delimited format. eg:

0, 1200, 1000, 0, 1000, 400, -1500

- Angle = angle of line from horizontal measured in an anti-clockwise direction
- Origin x = horizontal distance of start of line from setout point (always orthogonal)
- Origin y = vertical distance of start of line from setout point (always orthogonal)
- Shift u (x axis of line) = offset distance of start of repeat line measured parallel to start of line

(in the direction of the line, ie. to match the angle).*The Shift values are measured from the start of the line, not from the setout point*. - Shift v (y axis of line) = offset distance of start of repeat line measured perpendicular to start of line
- Pen down = length of solid line measured in the direction of the line (
*optional - it draws a continuous line if omitted*) - Pen up = length of gap in the line before the next segment of the
line starts repeating (measured in the direction of the line); is
always a minus value. (
*optional - as per pen down*)

*NB. I have labelled the shift directions as u & v (not x & y, as Autodesk labels them) because the directions relate to the axis of the line, not the whole pattern - so a vertical line would have a u offset measured vertically (labelled as x direction by Autodesk, which is confusing).*

## Stretcher Bond Hatching Definitions

- a series of continuous horizontal lines at regular spacing;
- Short vertical lines that run between alternate horizontal lines, at a spacing equal to the length of the brick/block/tile
- Another set of short vertical lines that run between alternate horizontal lines, at a spacing equal to the length of the brick/block/tile - but these are typically offset horizontally by half a length and vertically by one pattern height.

There are actually two ways to define this:

### Option 1 - separate definitions for the two vertical lines

*Stretcher-450x150-1/2, 450 x 150 1/2 stretcher bond;%TYPE=MODEL

0, 0,0, 0,150

90, 0,0, 0,450, 150,-150

90, 225,150, 0,450, 150,-150

The first row defines the horizontal lines

0, 0,0, 0,150

- The lines are at zero degrees (horizontal)
- The first line starts at 0 offset from the origin, both x and y (0,0)
- The repeat has a shift of zero horizontally (x or u), and 150mm vertically (y or v) from the line origin (0,150),
- The next repeat is the same values (0,150) from the start of the previous repeat.
- The line is continuous, as the are no pen up/down values

The second row defines the first set of vertical lines

90, 0,0, 0,450, 150,-150

- The lines are at 90 degrees (vertical )
- The first line starts at 0 offset from the origin, both x and y (0,0)
- The repeat has a shift of zero vertically (u) , and 450mm horizontally (v) , from the line origin (0,450)
- The next repeat is the same values (0,450) from the start of the previous repeat.
- The line is segmented, 150mm solid, 150mm gap (pen up/down 150,-150)

The v shift in this instance is horizontal, perpendicular to the line, with a positive value to the left of the line origin (same as pattern setout point in this case).

- As the pattern is symmetrical, it makes no difference if the v shift value is positive or negative
- Seen below in context, the pattern repeats in both directions from the origin:

The third row defines the second set of vertical lines

90, 225,150, 0,450, 150,-150

- The lines are at 90 degrees (vertical )
- The first line starts at 225mm x offset from the origin, and 150mm y offset from the origin (225,150) - ie. half a tile along and one tile up.
- The repeat has a shift of zero vertically (u) , and 450mm horizontally (v) , from the line origin (0,450)
- The next repeat is the same values (0,450) from the start of the previous repeat.
- The line is segmented, 150mm solid, 150mm gap (pen up/down 150,-150)

### Option 2 - one definition for both vertical lines

*Stretcher-450x150-1/2, 450 x 150 1/2 stretcher bond;%TYPE=MODEL

0, 0,0, 0,150

90, 0,0, 150,225, 150,-150

The first row defines the horizontal lines as per previous method

0, 0,0, 0,150

90, 0,0, 150,225, 150,-150

- The lines are at 90 degrees (vertical )
- The first line starts at 0 offset from the origin, both x and y (0,0)
- The repeat has a shift of 150mm vertically (u) , and 225mm horizontally (v) , from the line origin (150,225)
- The next repeat is the same values (150,225) from the start of the previous repeat.
- The line is segmented, 150mm solid, 150mm gap (pen up/down 150,-150)

- As the pattern is symmetrical, it makes no difference if the u and v shift values are positive or negative
- Seen below in context, the pattern repeats in both directions from the origin:

### One Third Shift Patterns

The same principles can be applied when the bond is staggered by differing proportions.### Option 1 - separate definitions for each vertical line

*Stretcher-450x150-1/3, 450 x 150 1/3 stretcher bond

;%TYPE=MODEL

0, 0,0, 0,150

90, 0,0, 0,450, 150,-300

90, 150,150, 0,450, 150,-300

90, 300,300, 0,450, 150,-300

90, 150,150, 0,450, 150,-300

- 90 degrees
- 150mm x line origin, 150mm y line origin
- Zero u shift repeat, 450mm v shift repeat
- 150mm Pen Down, 300mm gap (Pen Up)

- 90 degrees
- 300mm x line origin, 300mm y line origin
- Zero u shift repeat, 450mm v shift repeat
- 150mm Pen Down, 300mm gap (Pen Up)

### Option 2 - one definitions for all vertical lines

*Stretcher-450x150-1/2, 450 x 150 1/2 stretcher bond;%TYPE=MODEL

0, 0,0, 0,150

90, 0,0, 150,300, 150,-300

Horizontal shift (v) repeat has to be 2/3 of a tile (300mm)

As the joint offset is not half a tile, the same result can be achieved with a negative v shift repeat of -150mm:

0, 0,0, 0,150

90, 0,0, 150,-150, 150,-300

An offset by one third to the left could be achieved by a positive 150mm v shift:

0, 0,0, 0,150

90, 0,0, 150,150, 150,-300

### Two Third Shift Patterns

Some patterns cannot have their vertical lines defined by only one row, as you can't define a consistent diagonal repeat. Therefore you must have multiple rows for the vertical lines.*Staggered-450x150-2/3, 450 x 150 2/3 stretcher bond

;%TYPE=MODEL

0, 0,0, 0,150

90, 0,0, 0,450, 150,-150

90,

**300,150**, 0,450, 150,-150

The direction of stagger can be changed with the x origin value:

*Staggered-450x150+2/3, 450 x 150 2/3 stretcher bond

;%TYPE=MODEL

0, 0,0, 0,150

90, 0,0, 0,450, 150,-150

90,

**150,150**, 0,450, 150,-150

### Flemish Bond

More complex brick patterns require extra rows of definition:*Flemish-240x86, 240 x 86 (Australian Brick size) Flemish stretcher bond

;%TYPE=MODEL

0, 0,0, 0,86

90, 0,0, 0,360, 86,-86

90, 240,0, 0,360, 86,-86

90, 60,86, 0,360, 86,-86

90, 180,86, 0,360, 86,-86

You could continue this theme with increasing random looking patterns, but I'll leave that for you to figure out . . . . . .