Tutorials CadCraft help Walkthroughs
Use parameters and equations
Name sizes, drive them with expressions like width / 2, and type a number on a driven size to change what drives it.
Written for CadCraft 0.3. The same help is inside the app: press F1.
One table for every size
The Parameters panel (the Parameters button in the Parametric group, or type PARAMETERS) lists every dimensional constraint (d1, rad1, dia1, ang1, or the name you gave it) and your own parameters together. Any name can be used in any expression.
Each row has:
- Name: type a new one to rename it; every expression that uses it follows.
- Expression: a number (
40) or an expression (width / 2 + gap). Type in it and press ReturnEnter: the drawing follows. - Value: what it works out to. On a row an expression drives, you can type a number here too: CadCraft works out the parameter behind it. With
d1 = width / 2, typing30in d1's value setswidthto 60.
When two parameters drive a value (width / 2 + gap), a dialog asks which one to change. Every change is one undo step (⌘ZCtrl+Z).
Add your own
- Open the Parameters panel.
- Type a name (
gap) and a value (10), then choose Add. - Use it: in d1's expression, type
width / 2 + gapand press ReturnEnter.
Names start with a letter or _ and hold letters, digits and _. Function names, pi and unit names cannot be names.
Expressions
| Write | Means |
|---|---|
+ - * / ^ % | add, subtract, multiply, divide, power, remainder |
( ) | grouping |
sin cos tan asin acos atan atan2 | trigonometry in degrees |
sqrt pow exp ln log abs sign | roots, powers, logarithms |
ceil floor int round min max | rounding and limits |
if(a > b, x, y) | a choice |
pi | 3.14159… |
Numbers may carry a unit: 25mm, 1in, 2', 90deg. Lengths with a unit are turned into millimetres, so use units only in drawings measured in millimetres; elsewhere type plain numbers.
At the command line
-PARAMETERS does the same without the panel: N new, E edit (a dimensional constraint too), R rename, D delete, ? list.
What is refused
- An expression that uses itself, directly or through others: "width, d1 use each other."
- A value a size cannot take: a negative length, an angle over 180°.
- A value the drawing cannot take with its other constraints: nothing changes, and the message names the constraints in the way.
- Deleting a parameter something uses: the panel offers to write its value into them first. A dimensional constraint's name is deleted by deleting the constraint.