Envelope Parametric Model using Grasshopper

Transcription

1 Envelope Parametric Model using Grasshopper i

2 Table of Contents Overview... 1 Learning Objectives... 1 Pre-requisites... 1 Glossary... 1 Tutorial Parametric Model Structure Drivers Driving parameters Degrees to Radians Conversion Coordinates for Driver Corner Points Driving Points Driven Envelope Surfaces Creating Walls, Roof and Floor Window Surface ii

3 Overview This tutorial describes how to create a simple parametric model of a classroom using Grasshopper. This tutorial provides a preliminary understanding of what a parametric object is, and understanding of the notions of driven and derived parameters, control the behavior of the object in order to represent the design space intended as a valid range of possible design alternatives derived from the same topology. Learning Objectives Understanding how to build a hierarchical parametric structure Understanding the difference between driving and derived parameters Understanding object types Modeling a design space according to a given design problem Pre-requisites Rhino 5.0 and Grasshopper or newer Free download at Glossary The following acronyms are used in this document: DC: Double click on left button LC: Left click RC: Right click WS: Working Space GH: Grasshopper RH: Rhino Pt: Point G: Geometry input/output 1

4 Tutorial 1. Parametric Model Structure The model has two main components: the Drivers and the Envelope. While the Drivers correspond to the parameters and auxiliary geometry driving the actual geometry of the model, the Envelope groups the surfaces (Figure 1). In parametric modeling environments the user defines a set of parameters driving the model, intended as a single object or assembling of objects, through a tree of dependencies between objects and parameters (Figure 2). If any change occurs at the parameters level, it will be propagated consistently along the model. Figure 1 RH Geometric representation: Drivers (Left), Envelope (Right) Figure 2 GH Parametric Model: Drivers (Left), Envelope (Right) 2

5 2. Drivers Figure Driving parameters Crating parameters Go to Params, Input, Number Slider (Figure 4) and drag it to the work space. Figure 4 3

6 Edit parameter DC on the new Slider (Figure 5) and change the name to buildinglength. Set it as integer by selecting N (R or real for decimal values). DC to set the minimum value to 24 and maximum to 48. Select the green check mark to commit changes. Repeating the same process and create the following parameters (Figure 3): orientation: N, Min 0, Max 360 buildingheight: N, Min 12, Max 16 windowwallratio: R, Min 0.1, Max 0.9 Figure Create a constant value Go to Params, Primitive, Integer (Figure 6) and drag the icon to the WS Figure 6 4

7 RC on the Int parameter and edit name to Area 960 sf, set the Integer value to 960 and commit changes (Figure 7) Figure Labeling and Grouping Label your parameters using the Scribble tool from Params, Utilities (Figure 8) Figure 8 Select all the parameters and label and group them using Ctrl + G or Edit, Group (Figure 9) Figure Degrees to Radians Conversion 5

8 Figure Custom converter Since designers use degrees and GH reads radians, we need to translate the user s input into computer readable information. There is a function to do that automatically, but we will implement the following formula to learn how to use the Maths operatiors: Go to Math, Operators, Multiplication and drag the icon to the WS (Figure 11). Repeat the process for the Division operation. Figure 11 Go to Maths, Utilities (click on Util and select π), and drag the Pi number into the WS (Figure 12). Figure 12 6

9 Create another constant value of 180 as in section and then assemble everything to build your unit converter as in Figure 10. Figure Built-in converter You can skip this process and use built-in function (Figure 14) Radians from Maths, Trig. Figure Coordinates for Driver Corner Points Figure 15 7

10 Deriving the width of the building Since the area of the building is constant (960 sf), we can derive the width by dividing the area over the shifting length of the length of building. We can verify the resulting value by adding a panel from Params, Input, Panel (Figure 16). Figure Deriving coordinates Since the center of the Rhino WS is right on the middle of the Classroom. We need to convert the length and width of the building into X and Y coordinates for every corner of the floor plan. For example if the length and resulting width are 32 and 30 respectively, the coordinates for every corner should be: upper left: (-16,15) lower left: (-16, -15) lower right: (16,-15) upper right: (16,15) Figure 17 The above values can be generated by using the Maths operators in sequential steps (Figure18) similar to those in section Figure Driving Points 8

11 Figure Creating Points To create the actual corner points go to Vector, Point and drag four Points Pt to the WS (Figure 20). Provide the right X,Y coordinates created in section 2.3. Z by default is 0. Figure 20 9

12 Rotate Points In order to rotate the corner point according to the orientation parameter we need to add the Rotate operator from Transform, Euclidean. Drag into the WS one Rotate operator per point. Pass the points Pt to the G slot (G for geometry) of the Rotate and the angle translated into Radians (R)(A for angle?) (Figure 21). Try to rotate the points by changing the value of the orientation parameter Figure 21 Hide the original points Pt, RC on every point and set the Preview option off (Figure 22). It is important to notice that the Rotate operator is not rotating the original point, but creating a rotated version of it. That is why we need to hide the original one. If we do not hide them we will see points in the original location and the rotated point. Keep in mind that GH creates a rotated copy of the point rather rotating the actual original point. Figure 22 10

13 3. Driven Envelope Surfaces Figure Creating Walls, Roof and Floor Creating the roof corner points Four new Points must be created for the roof corners of the envelope. The resulting set of eight points will provide the inputs to define the corners of the Roof, Walls and Floor of the Classroom (Figure 24) Figure 24 11

14 To create the roof corners we will move a copy of the floor corners of the floor according to the buildingheight parameter. To create the copy go to Transform, Euclidean, Move and drag the icon to the WS (Figure 25). The Move operator requires two inputs: the Geometry G, in this case the corner points, and the vertical translation vector T. Figure 25 After dragging one Move operator per corner, go to Vector, Vector, VectorXYZ and drag the icon into the WS. Pass the buildingheight parameter to the new Vector to define the translation vertical value. Finally, pass the corner points to the G slot of the Move operators and the vertical translation vector to the T slot (Figure 26). Figure Creating the envelop surfaces The envelope is defined by six different surfaces (Figure 27) created by the 4Point Surface operator. Figure 27 12

15 The 4Point Surface operator creates surfaces from three or four corner points. It is in Surface, Freeform. Figure 28 Drag into the WS one 4Point Surface operator per surface, and RC to rename them to identify the Walls, Roof and Floor of the Classroom (Figure 29). Finally, use corner points of the floor plan and roof as inputs to create the six surfaces of the envelope as in Figure 23. Note: Be sure to accurately select the correct inputs when creating envelope surfaces. Much like creating four-point surfaces manually in Rhino, you must choose points in a proper order. Figure 29 13

16 3.3. Window Surface Parametric space The window surface is made by a scaled copy of an existing wall. Since the walls rotate, the references to create the window surface must follow the parametric U,V coordinates of the wall. Drag a PointOriented from Vector, Point into the WS. Chose a wall as a base plane P, and provide the U and V parametric coordinates by dividing by 2 the buildingheight and buildingwidth parameters (Figure 30). Remember that buildingwidth is derived Scaling Drag the Scale operator from Transform, Affine into the WS and provide the input geometry Wall to the G slot, the PointOriented Pt to the center C and the windowwallratio parameter to the F scaling factor (Figure 30). The resulting window surface should be right in the center of the wall as shown in figure 27. Figure 30 14