# Guide

URL: https://smartcut.dev/docs/guide

> Helpful definitions and ways of doing things

However you are interacting with the API there are some universal ways of doing things which are defined below.

## Coordinate system & side definitions

Throughout the process we need to be able to refer to sides and directions, while catering for part rotation.

For our x and y coordinate system, y increases as you move up.

The side labels are used throughout. L indicates stock length if used as a direction or the longer side. W indicates stock width (shorter side) if used as a direction or the shorter side.

### Stock

- Stock is always arranges with the long sides horizontally. Stock never rotates.
- Longer sides are labelled L1 and L2.
- Shorter sides are known as the width and labelled W1 and W2.
- Adding trim to stock.trim.l1 will trim moving in from the bottom side, reducing the width of the stock.

![Coordinate system stock](/images/stock-coords.png)

### Stock

- Parts can rotate, but as the L1,L2,W1,W2 sides refer to the longer and shorter sides these values do not change with rotation.

![Coordinate system parts](/images/part-coords.png)

## Orientation models

To suit various local conventions for defining part orientation we support different orientation models. These define how part rotation is defined and how sides are labelled.

### Model 0 (default, used by API)

- Model 0 is used by the API.
- For model 0, the part orientation is defined by the orientationLock property on the part. The values for part.l and part.w DO NOT affect rotation.
- orientationLock = 'l' means the longer side of the part is aligned with the longer side of the stock (this is horizontal on our diagrams).

### Model 1 (can be used by UI)

- Orientation is controlled by the values in the 'length' / 'l' and 'width' / 'w' properties of each part.
- The part is rotated so that the side defined by the 'l' property is aligned with the longer side of the stock.
- Clicking the rotation button allows for free rotation, overriding the l/w defined orientation.
- Sides are not mapped in outputs.

### Model 1 (can be used by UI)

- Orientation is controlled by the values in the 'length' / 'l' and 'width' / 'w' properties of each part.
- The value used in the 'length' / 'l' property determines the grain dimension.
- Clicking the rotation button allows for free rotation, overriding the l/w defined orientation.
- Banding L values match L column values
- L and W columns are updated in exports to match local expectations (e.g. CSV ouput)
- Sides are not mapped in outputs.

### Use of sides (L1,L2,W1,W2)

Please note when sides are defined directly (for example banding.sides or trim) - this will always use our internal definition of L1,L2,W1,W2 regardless of orientation model (as shown in the diagrams above).