Welcome to AR-327 !!


Today's learning objectives:

  • Get familiar with the RhinoCommon API
  • Create simple geometries such as points and lines
  • Get confident in using the inherent methods and properties of these objects

Introduction

Introduction


Today we will learn how to create basic geometry objects in python. To structure today's lecture, we will follow the example of CNC toolpath generation.

Introduction


Today we will learn how to create basic geometry objects in python. To structure today's lecture, we will follow the example of CNC toolpath generation.

Introduction


We will have 3 in-class exercices:
  • Create points in a reference plane
  • Create lines between the reference points
  • Create a polyline as toolpath

Points

Points

How would you define a point in 3D?

Points

Points are defined by 3 coordinates: x, y, z
They have no direction, no side or orientation

Points

And in code ?

Points

And in code ? 
        
            import Rhino

            x = 3
            y = 6
            z = 0

            my_point = Rhino.Geometry.Point3d(x, y, z)

Points:

a few properties 

        
            import Rhino

            my_point = Rhino.Geometry.Point3d(3, 6,0)

            x = my_point.X # The X property returns the x coordinate of the object of class Point3d
            y = my_point.Y 
            z = my_point.Z

Points:

a method 

        
            import Rhino

            p1 = Rhino.Geometry.Point3d(3, 6, 0)
            p2 = Rhino.Geometry.Point3d(2, 1, 6)

            distance = p2.DistanceTo(p1)

Points:

a few operators 

        
            import Rhino

            # addition, substration, multiplication and division are supported
            p3 = p1 + p2
            p3 = -p2
            p3 = 2*p1
            p3 = p1/10

Points:

a few operators 

        
            import Rhino

            # addition, substration, multiplication and division are supported
            p3 = p1 + p2
            p3 = -p2
            p3 = 2*p1
            p3 = p1/10
Please note that the python interpreter will not know by default what "p1 + p2" means. Rhino developpers have defined themselves what the operation "p1 + p2" should generate

Vectors

Vectors

How would you define a vector ?

Vectors

Vectors are abstract geometries
They are composed of a magnitude and direction:

Vector

And in code ?

Vector

And in code ? 
        
            import Rhino

            my_vector = Rhino.Geometry.Vector3d(1, 2, 3)

Vector

a few properties 

        
            import Rhino

            my_vector = Rhino.Geometry.Vector3d(1, 2, 3)

            vector_length = my_vector.Length

            x_coord = my_vector.X

            is_unit = my_vector.IsUnitVector

Vector

a few methods 

        
            import Rhino
            TOL = Rhino.RhinoDoc.ActiveDoc.ModelAbsoluteTolerance

            v1 = Rhino.Geometry.Vector3d(1, 2, 3)
            v2 = Rhino.Geometry.Vector3d(0, 1, 1)

            v3 = Rhino.Geometry.Vector3d.CrossProduct(v1, v2)

            is_para = v2.IsParallelTo(v1, TOL)

            v1.Unitize()

Planes

Planes

How would you define planes ?

Planes

Planes are abstract geometries
Planes are composed of an origin and a set of x, y, and z axes

Planes

And in code ?

Planes

And in code ? 

        
            import Rhino

            origin = Rhino.Geometry.Point3d(1, 1, 1)
            normal = Rhino.Geometry.Vector3d(0, 0, 1)

            # One way of creating a plane, among many other
            my_plane = Rhino.Geometry.Plane(origin, normal)

Planes

And in code ? 

        
            import Rhino
            
            horizontal_plane = Rhino.Geometry.Plane.WorldXY

Planes

A few properties 

        
            # simply retrieve the normal (z axis) and origin of the plane
            plane_normal = my_plane.Normal
            plane_origin = my_plane.Origin

Planes

A few methods 

        
            u = 1
            v = 3
            w = 2

            pt = my_plane.PointAt(u, v, w)

            my_plane.Flip()

Exercice on planes (10 mins):

Go to the website's page on Planes and solve the the second exercie

Lines

Lines

How would you define a line ?

Lines

Lines have a start point and an end point
Lines have a length and a direction

Lines

And in code ?

Lines

And in code ? 
        
            import Rhino

            p1 = Rhino.Geometry.Point3d(0, 0, 0)
            p2 = Rhino.Geometry.Point3d(1, 1, 1)
            my_line = Rhino.Geometry.Line(p1, p2)

Lines

A few properties: 

        
            direction_vector = my_line.Direction

            start_point = my_line.From

            end_point = my_line.To

Lines

A few methods: 

        
            my_line.Extend(1,2) 

            my_line.Flip()

            my_point = my_line.PointAt(0.5)
            my_point = my_line.PointAtLength(4.5)

Exercice on lines (10 mins):

Go to the website's page on Planes and solve the the first exercie

Polylines

Polylines

How would you define a polyline ?

Polylines

Polylines are a succession of interconnected lines:

Polylines

And in code ? 

        
            import Rhino

            # Creating a list of points.
            pts = [Rhino.Geometry.Point3d(0, 0, 0),
                Rhino.Geometry.Point3d(1, 0, 0),
                Rhino.Geometry.Point3d(0, 2, 0)]

            my_polyline = Rhino.Geometry.Polyline(pts)

Polylines

A few properties 

        
            is_closed = my_polyline.IsClosed

            n_segments = my_polyline.SegmentCount

            length = my_polyline.Length

Polylines

A few methods 

        
            center_point = my_polyline.CenterPoint()

            length_parameter = 5 + 0.5
            mid_point_of_fifth_segment = my_polyline.PointAt(length_parameter)

Exercice on polylines (10 mins):

Go to the website's page on Planes and solve the the first exercice. You will need the accompanying 3dm file

Assignment for next week: