Kaust rhino workshop 2011

transcript

SCRIPTINGINRHINOKAUST‐ April,2011

Geometric Modeling and Scientific Visualization CenterGeometricModelingandScientificVisualizationCenter

KhaledMohamedAhmedAbdElGawadwww.khaledarch.comwww.khaledarch.com

Outline Introduction VBScript Essentials Operators and functionsp

Conditional Execution/Branching Arrays Surface and Polysurface MethodsSurface and Polysurface Methods

Show Cases Grasshopper Overview Useful Resources

Useful Resources

Introduction

WhatWeCanDoUsingRhinoScript?

Computational Design Solution ‐ IAP Coursehttp://www.kaschaandjohn.com/rhinoscripting/

http://www.rhinoscript.org/gallery/2

Scriptingvs.ProgrammingLanguages. These days, the line between a scripting language and

i l i bl da programming language is blurred.

Scripting Languages: Run Inside other programsRun Inside other programs Are not compiled. A t d t it Are easy to use and easy to write. Scripting languages are used to build complex software. Scripting languages are so efficient

p g g g

Macros Rhinoceros is based on

a command linea command‐line interface.

A macro is a prerecorded list of orders for Rhino to executeexecute.

Macros Example:

A (0, 0, 0)

B(10, 0, 0)

Open100 Add line Save FilesRhino Files

Macros allow you to automate tasks you would normally do by hand but not by brain.

Scripts Scripts are text files which are interpreted one line at

ia time.

Scripts have control over which line is executed next.

We must familiarize ourselves with the language rules f VBS ript b f fl t lof VBScript before we can use flow control.

HowtoRunaScript? We could store scripts as external text files and have Rhino load them whenever we want to run themRhino load them whenever we want to run them

We could also use Rhino's in‐build script editor. _EditScript Command line_ p Tools Rhinoscript Edit

HowtoRunaScript?The Script Window will show upshow up

Then we can write i t i t thour script into the

Script Editor window th li k tthen click execute

HowtoRunaScript? Or we can embed scripts in toolbar buttons, which makes it very hard to edit them but much easier tomakes it very hard to edit them, but much easier to distribute them.

VBScriptEssentials

Languageorigin VBScript is a member of the BASIC language family.

The language was designed to be easy for humans to understand.

BASIC stands for Beginner’s All‐purpose Symbolic Instruction Code.Instruction Code.

Rhino Scripting syntax rules are basically the same as Rhino Scripting syntax rules are basically the same as Visual BASIC.

FlowControl We use it to skip certain lines of code or

To execute others more than once.

To jump to different lines in our script and back again.To jump to different lines in our script and back again.

You can add conditional statements to your code You can add conditional statements to your code which allow you to shield off certain portion

Variable Data From a programmer's point of view, a variable is a location in your computer's memory in which you canlocation in your computer s memory in which you can store a value and from which you can later retrieve that valuethat value.

A visual representation of memory

Variable Data Whenever we need to store data or perform calculations or logic operations we need variables tocalculations or logic operations we need variables to remember the results.

33 33..44 datadata

X Y Variable name

Variable Data There are different data types: Integers, doubles, Booleans strings and Null variableBooleans, strings, and Null variable.

D blInteger

Double Boolean

NullSt i datadataString datadata

Variable name

Variable Data: Integers and Doubles Doubles are numeric variables which can store numbers with decimalsnumbers with decimals.

Variable Data: Booleans Boolean variables can only store two values mostly referred to as Yes or No True or Falsereferred to as Yes or No, True or False.

In VBScript we never write "0" or "1" or "Yes" or "No”

We always use "True" or "False".

Variable Data: Strings Strings are used to store text.

Whenever you add quotes around stuff in VBScript, it automatically becomes a String.

So if we encapsulate a number in quotes, it will become textbecome text

Variable Data: Strings String Assignment and Concatenation

Variable Data: Strings When using & you can treat numeric variables as StringsStrings

Variable Data: Null Variable When a variable has no value, it considered to be null.

Having a null value is different than having a value of 0, since 0 is an actual value.

Whenever we ask Rhino a question which might not have an answer, we need a way for Rhino to say "I don't know"

Using Variables Variable Declaration: W ll d l i bl i h Di We normally declare a variable using the Dimkeyword.

We can declare multiple variables using a singleWe can declare multiple variables using a single Dim keyword if we comma‐separate them.

Using Variables Variable Names: I i d d fi It is recommended to use prefixes. Use a 3 character prefix which indicates the type of variable

V i bl t P fi E lVariable type Prefix ExampleBoolean bln blnSuccessInteger int intXDouble dbl dblYDouble dbl dblYString str strfood

Using Variables Variable Assignment: B f f i bl Before you can use any of your variables, you must first assign them a value.

OperatorsandFunctions

Operators and Functions

Th i fi t i th f ll i The previous figure contains the followings: Numbers (15, 26, 2.33 and 55) Variables (x, y, and z) Operators ( =, +, * and /)p ( , , /) Functions (Sin, Sqr, Tan and Log)

Operators in RhinoScript Arithmetic Operators C i O Concatenation Operators Comparison Operators Logical and bitwise Operators

Operators in RhinoScript Operator Precedence

The acronym PEMDAS or "Please Excuse My Dear Aunt Sally" is common.

It stands for Parentheses, Exponents, Multiplication, Division, Addition, Subtraction.Multiplication, ivision, Addition, Subtraction.

Operators in RhinoScript Operator Precedence B d i i f h ld d h Based on previous info how could we code the following?

PEMDAS

Operators in RhinoScript Operator Precedence B d i i f h ld d h Based on previous info how could we code the following?

PEMDAS

Solution:

y = Sqr(x ^ 2 + (x ‐ 1)) / (x ‐ 3) ) + Abs( (2 * x) / (x ^ (0.5 * x))

Solution:

Operators in RhinoScript Operator Precedence T i lif h i d i To simplify the equation we can spread it out over multiple lines of code

y = Sqr(x ^ 2 + (x ‐ 1)) / (x ‐ 3) ) + Abs( (2 * x) / (x ^ (0.5 * x))

Operators in RhinoScript: Logical Operators

Logical operators mostly work on Booleans.

Boolean mathematics were developed by George Boole (1815‐1864) and today they are at the very core of the entire digital industry.

Boolean algebra provides us with tools to analyze, compare and describe sets of data.

M f h B l O N A d Most famous three Boolean Operators are: Not, And, and Or.

A good way to exercise your own Boolean logic is to use Venn‐diagrams.

A Venn diagram is a graphical representation of Boolean sets where every region contains a (sub) setBoolean sets, where every region contains a (sub) set of values that share a common property.

Operators in RhinoScript: Logical Operators Venn diagrams are useful for simple problems, but once you start dealing with more than three regions itonce you start dealing with more than three regions it becomes a bit opaque. 6 i l V di P tt b t t ti l 6‐regional Venn diagram. Pretty, but not very practical

Functions in RhinoScript Microsoft VBScript has 89 built in functions:

Sin(n) Sine of a number

Cos(n) Cosine of a numberCos(n) Cosine of a number

Atn(n) ArcTangent of a number

Log(n) Natural logarithm of a number larger than 0

Sqr(n) Square root of any positive numberSqr(n) Square root of any positive number

Abs(n) Absoluter (positive) value of any number

Functions in RhinoScript Rhino adds over 200 functions called methods:

Rhino.command (“_Move 0, 0, 0 2, 0, 1”)

Rhino.UnselectAllobjects()Rhino.UnselectAllobjects()

Rhino.Selectobject (strCurveID) Rhino.Copyobject (strCurveID) Rhino.GetObject (“Select an object”)Rhino.GetObject ( Select an object )

What is a Function? A function is a closed body of code that executes a specific taskspecific task.

A function is like a black box. It takes in input, does something with it does something with it,

and then spits out an answer. A function may not take any inputs at all or it may not return anything at all.return anything at all.

Function Example

Why Would We Need Functions? we can write it as a single function and access the same function again and again as many times as it issame function again and again as many times as it is required.

We can avoid writing redundant code of some instructions again and again.

Programs with using functions are compact & easy to understand.understand.

Testing and correcting errors is much easier.

Why Would We Need Functions? We can understand the flow of program, and its code easily since the readability is enhanced while using theeasily since the readability is enhanced while using the functions.

A single function written in a program can also be used in other programs also.

Script File Structure Every script must implement a certain structure which tells the interpreter what's whattells the interpreter what s what.

Script File Structure Option Explicit: It is optional, but it is highly recommended.

If you use it, you have to define all your variables before you can useyour variables before you can use them.

If you don’t use it your variables If you don t use it, your variables will be declared for you by the compilercompiler.

Script File Structure Option Explicit: It may also contains a set of comments.

Comments are blocks of text in the script which are ignored by thescript which are ignored by the compiler and the interpreter.

comments are used to add comments are used to add explanations to a file, or to disable certain lines of codecertain lines of code.

Comments are always preceded by

an apostrophe.

Script File Structure Global Variables: They are optional. Typically you do not need globalTypically you do not need global variables and you're usually better off without them.off without them.

Script File Structure The Main Function

Every script requires at least one function contains the main code of the script.

it can place calls to any number ofit can place calls to any number of other functions

It delineates the extents of the It delineates the extents of the script.

The script starts running as soon as this function is called and it stops

when the function completes.

A Simple Function Example

ConditionalExecution/Branching

Conditional execution or Branching IF….Then Statement

Select case LoopingLooping

Conditional loops Incremental loops

Nested LoopsNested Loops

IF….Then Statement If we have three different situations:

1. If the object is a curve, delete it.

2. If the object is a short curve, delete it.2. If the object is a short curve, delete it.

3. If the object is a short curve, delete it, otherwise it t th “ ” lmove it to the “curves” layer.

How would this be implemented using RhinoScript?

IF….Then Statement If we have three different situations:

1. If the object is a curve, delete it.

2. If the object is a short curve, delete it.2. If the object is a short curve, delete it.

3. If the object is a short curve, delete it, otherwise it t th “ ” lmove it to the “curves” layer.

How would this be implemented using RhinoScript?

This is so easy. We just need to learn how conditional syntax works.

IF….Then Statement 1. If the object is a curve, delete it.

2. If the object is a short curve, delete it.

IF….Then Statement 3. If the object is a short curve, delete it, otherwise

move it to the “curves” layermove it to the curves layer.

Select … Case We use Select…Case when we want to check the

equalityequality.

Select … Case (Sort objects based on type)

An Integer to store the An Integer to store the Rhi ObjRhi Obj T dT dRhino ObjectRhino Object‐‐Type codeType code

This means the object This means the object does not exist; abortdoes not exist; abort

A String to store a layer A String to store a layer namename

Compare the actual Compare the actual d h hd h htype code with the type code with the

preset onespreset ones

Points andPoints and PointCloudPointCloudPoints and Points and PointCloudPointCloudobjectsobjects

CurvesCurves

Surfaces and Surfaces and PolySurfacesPolySurfacesPolySurfacesPolySurfaces

MeshesMeshes

LightsLights

Annotations and Annotations and TextDotsTextDots

BlocksBlocks

Any other objects; Any other objects; AbortAbort

If h lIf h lIf the layer we are If the layer we are about to assign does about to assign does

not yet existnot yet existnot yet exist…not yet exist…

Create itCreate it

Assign the object to the Assign the object to the layerlayer

Looping Executing certain lines of code more than once is

called looping in programming slangcalled looping in programming slang.

The two most important syntax for loops:

Conditional Loops (Do loop Do While loop Conditional Loops (Do…loop, Do While…loop, Do Until…loop)

Incremental loops (For...Next)

Conditional loops We use it when we do not know how many iterations

we will need in advancewe will need in advance.

This type is called a Do…Loop.

Conditional loops: Do…Loop This example script contains an endless Do…Loop

which can only be cancelled by the user pressingwhich can only be cancelled by the user pressing (and holding) escape.

Conditional loops: Do…Loop

1 & 2: Option Explicit declaration and comments about who's who and what's whatabout who s who and what s what

4: Main Function call

5:Main function declaration

6 W d l i bl hi h i bl f t i 6:We declare a variable which is capable of storing a Rhino object ID

7:We create a new Rhino Text object

Rhi AddT t ( t T t P i t [ dblH i ht [ t F t [Rhino.AddText (strText, arrPoint [, dblHeight [, strFont [, intStyle]]])

8: Just in case the text object hasn't been created we need to abort the subroutine in order to prevent anneed to abort the subroutine in order to prevent an error later on.

10: Starting the loop

11 W d t h th t t d 11: We need to change the text once every second. The Rhino.Sleep() method will pause Rhino for the specified amo nt of milliseconds

specified amount of milliseconds.

12: Here we replace the text in the object with a new String representing the current system time.String representing the current system time.

Conditional loops: Do While…Loop

This kind of loop syntax will abort the loop when S C di i i lSomeCondition is False.

Conditional loops: Do Until…Loop

If we want the loop to terminate when a condition b i d f l h U ilbecomes True instead of False, we can use the Until keyword instead of the While keyword

Conditional loops: Do…Loop While

You can be guaranteed that DoSomething will be ll d l b i h f ll icalled at least once by using the following syntax:

Incremental loops

We use it when the number of iterations is known in dadvance.

The variable i starts out by being equal to A and it is incremented by N until it becomes larger than Bincremented by N until it becomes larger than B.

Once i > B the loop will terminate.

Incremental loops

Example

Nested Loops

The following example shows how nested For…Next b d di ib istructures can be used to compute distributions:

Arrays

Arrays An array is a list of variables.

Arrays start counting at zero.

The first element of an array is the element withThe first element of an array is the element with index 0.

Arrays are just like other variables in VBScript with Arrays are just like other variables in VBScript with the exception that we have to use parenthesis to set and retrieve valuesand retrieve values.

Arrays

you can also use a shorthand notation in which case h h h h blyou have to omit the parenthesis in the variable

declaration:

The Array() function in VBScript takes any number of The Array() function in VBScript takes any number of variables and turns them into an array.

You can add as many arguments as you like

Arrays

In RhinoScript, coordinates are defined as arrays of h b l d hthree numbers. Element 0 corresponds with x, element 1 with y and element 2 with z.

SurfaceandPolysurface Methods

Basic 3D Geometry: Static Creation

Add Sphere

Add Box

Add Cylinder Add Cylinder

Add Cone

Add Torus

Basic 3D Geometry: Dynamic Creation

Add Sphere Exercise

Add Box

Add CylinderPlease write a script

Exercise

Add Cylinder

Add Coneto create a Box by getting the length, width and the height

Add Torus width and the height from the user.

Please do the samePlease do the same for Cylinder, cone and Torus

ShowCases

Example 1: Tree Example

Example 2: Mesh Generation

GrasshopperOverview

UsefulResources

Useful Resources http://wiki.mcneel.com/developer/rhinoscript

Everything about RhinoScript

http://www.rhino3d.com/developer.htm#vbs

Useful Resources about rhino scripting and Grasshopper

htt // hi i t / t t http://www.rhinoscript.org/start

Important community for RhinoScripting and

Grasshopper

Ihopeyouhaveenjoyedit!

Khaled Abd El GawadKhaledAbdElGawadwww.khaledarch.com

Kaust rhino workshop 2011

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