The utils.stretchToScale() function calculates the scale for a given amount of
stretch.
Signature
Javascript
float utils.stretchToScale(float stretch)
Notes
The way people measure stretch intuitively is different from the way we handle stretch in code.
When people say fabric has 25% stretch they mean that 10 cm of fabric can stretch to 12.5 cm. In code that means we would need to scale non-stretch lengths by 80% to get the correct lengths to use in patterns with 25% stretch fabric.
Pattern designers need a way to calculate the scaling factor to use for their pattern part lengths, given a fabric stretch percentage. This function does that by returning:
Javascript
1 / (1 + parseFloat(stretch))