BK3070 Exam Solutions 1

BK3070 Exam Q2 2012/2013

The exam consists out of 5 questions, each question represents knowledge that as been learned this semester.

Different solutions are possible to answer the same question. This depends on the components that are used and if the components are used in an efficient way.

All the TO&I exams can be found here .

Direct link to BK3070 Q2 exam questions and to Grasshopper start files .

LMB: Left Mouse Button

MMB: Middle Mouse Button

RMB: Right Mouse Button

Solution question 1

A start file is given with two Lines and some components to divide a surface, see figure.

Create a surface with a diagonal construction between the two lines, see figure.

• Create a correct surface (0.5 point)
• Divide the surface (0.5 point)
• Create diagonal lines (0.5 point)
• Create tube shape diagonals (0.5 point)

Step 1 - Create Surface

Given are 4 point coordinates (x,y,z) made with PANEL components. With these points two lines are made. Create a surface between the two lines by using the LOFT component. Connect the first line with the LOFT component and then add the second line (use LEFT MOUSE BUTTON and SHIFT).

Step 2 - Divide Surface

Next step is to divide the surface from Step 1 into smaller equal segments and extract them. With the DIVIDE DOMAIN2 component the surface can be divide into equal segments. The number of segments depends on the U & V numbers that divide the surface. An U & V of 15 will give 225 segments (15*15=225). Now create the ISOTRIM(SUBSURFACE) component to extract all the surface segments.

TIP

When you connect the ISOTRIM(SUBSURFACE) output to a LIST ITEM component with SLIDER (maximum 224) you can cycle through the different surface segments. The SLIDER component maximum is 224, do you know why? With the LIST ITEM component you can choose a single surface segment from the total of 225 segments. This is not part of the Exam, but to show you how the ISOTRIM works.

Step 3 Create Surface Points

Next step is to create surface points (vertices) to make diagonal lines. With the BREP COMPONENTS (EXPLODE) components you can get the points (vertices) of the different surface segments. To get different groups of points use 4 LIST ITEM components. Create 4 index numbers (0-3) with PANELS and connect them to the LIST ITEM components.

Step 4 Create Diagonal Tubes (Pipes)

Create the diagonal lines by connecting the first and the third LIST ITEM components to the first LINE component. Now connect the second and the fourth LIST ITEM components to the second LINE component. This will create the diagonal lines in two directions. To create the diagonal tubes connect the two LINE components to a PIPE component. Create a SLIDER component to connect to the Radius input of the PIPE component.

Solution question 2

A start file is given with two lines, see figure. The edges of a surface are combined to a single line that has been offset.

Create a correct inward offset of 3 and create a surface between the original and offset line, this can be done with the BOUNDARY SURFACES component(PLANAR SURFACE in older Grasshopper versions). Give this surface a perpendicular thickness of 6. You can use the EVALUATE SURFACE component to get the right direction (normal vector) of the surface. For this purpose you will need a UV coordinate that has been given {0.5,0.5,0.0}.

• Create a correct surface and offset (0.5 point)
• Thickness surface (0.5 point)
• Thickness has the correct value and direction (0.5 point)
• Efficiency method (0.5 point)

Step 1 - Create Surface

Given are 4 point coordinates (x,y,z) made with PANEL components. With these points a 4 Point Surface is made. The edges of the surface are extracted with the BREP COMPONENTS (EXPLODE) component. These lines are connected with the JOIN CURVES component.

This line can be offset inwards with a distance of 3. The SLIDER component is connected to the Distance Parameter of the OFFSET component for this purpose. If the offset goes outwards you can place a NEGATIVE component between the slider and the distance parameter. TIP: You can also create an expression (-D) for the distance parameter.

To create a surface between the line and the offset line use the BOUNDARY SURFACES component (in older versions PLANAR SURFACE). Connect both lines to the BOUNDARY SURFACES component and flatten the input. This can also be done with the FLATTEN TREE component.

Step 2 - Create Thickness (Extrusion)

To give the offset surface a thickness we need the Normal Vector. This vector is perpendicular to the surface (loodrecht op het vlak). With the EVALUATE SURFACE component this Normal Vector can be found. First you will have to choose on what point of the surface you want to find the normal. If you want roughly the center of the surface, input {0.5,0.5,0} on the UV input of the EVALUATE SURFACE component. Also connect the surface to the EVALUATE SURFACE component.

To extrude the surface in the right direction the Normal Vector output [N] has to be reversed with the REVERSE component. This will reverse the Normal Vector. The next step is to create a extrusion of 6. For this we will use a MULTIPLICATION component and a SLIDER component set on 6. Connect the REVERSE component and the SLIDER component to the MULTIPLICATION component.

To give the surface a thickness we will use the EXTRUDE component. Connect both the BOUNDARY SURFACES component (in older versions PLANAR SURFACE) and the MULTIPLICATION component to the EXTRUDE component.

Solution question 3

Given is a full Grasshopper definition without explanation.

Add comments to each of the empty panels. The point is that you can explain what happens in groups, do not you just describe the components. Give all sliders a logical name to match the action that follows afterwards.

Add comments to each of the empty PANELS. Explain what is happening in the groups, don't just only describe the working of the components. Give all the sliders a logical name that corresponds to the actions that follows afterwards.

• Each PANEL contains a correct explanation of the corresponding script (0.5 point)
• The Sliders have a logical name (0.5 point)

Solution question 4

A start file is given with a grid and some components to create spheres.

Create spheres on all the grid point. Each row has to have a number of small and big spheres.

Use a RANDOM component to determine the number of small and big spheres per row. Connect the DOMAIN and SERIES components to the RANDOM component. Use the SPLIT LIST component to split the points of each row in two. Give the small spheres a red color and the large spheres a blue color.

• Use the RANDOM component (0.5 point)
• Split the grid points into two lists (0.5 point)
• Create spheres with different diameter and color (0.5 point)
• Connect the DOMAIN component (0.5 point)

Step 1 - Split Grid Points

Given is a 2D Square Grid with eleven rows and each row has eleven points (This can be shown by connecting a PANEL component to the grid output). We want to split these different row points in a random way and put spheres on the points with a different size and color.

Create a RANDOM component to create a list of random numbers. Connect the PANEL component with value 10 to the B input of the DOMAIN component and to the C input of the SERIES component. This will create a list of 10 random values between 0 and 9 (This can be shown by connecting a PANEL component to the Random output).

Create a SPLIT LIST component to split the grid points on each row. Connect the Points output of the SQUARE GRID component to the SPLIT LIST component. And connect the RANDOM component output to the Index input of the SPLIT LIST component. The index will create the random point variation of each row. Now you will have two list of points of each row.

Step 2 - Create Spheres

To create the spheres with different size and color connect the output A of the SPLIT LIST component to the first SPHERE component. And connect the SPHERE component output to the CUSTOM PREVIEW component with the Red Color Swatch. Now connect the output B of the SPLIT LIST component to the other SPHERE component and also connect the Blue Color Swatch. This will give the desired end result.

Solution question 5

A start file is given with a line that is divided and some components you can use.

Create a second line above the first line in the Z-direction. Next create a truss (vakwerk) between the two horizontal lines. This truss consists out of vertical and diagonal elements. Give the truss a width of 0.8 by moving all the lines of the truss in the Y-direction. Use the LOFT component to create surfaces between the lines. Give the two horizontal lines a round construction with the PIPE component. Make sure the Pipes are precisely in the middle of the truss. So the radius of the PIPE component always has to be the half of the truss width. Some components have been given in the Grasshopper start file.

• Create vertical elements (0.5 point)
• Create diagonal elements (0.5 point)
• Create vertical and diagonal surfaces (0.5 point)
• Give the two horizontal lines a round construction (0.5 point)

Step 1 - Create Truss lines

First step is to copy the horizontal line in the Z-direction. This can be done with the MOVE component. Set the SLIDER component connected to the UNIT Z component on 3. Connect the LINE SDL component and the UNIT Z component with the MOVE component. (The MOVE component will copy and move geometry.) To divide the upper horizontal line connect it to the second DIVIDE DISTANCE component. The distance between the points is 2, see distance parameters of the DIVIDE DISTANCE component.

Create vertical lines by connection the two DIVIDE CURVE component to the first LINE component. To create the diagonal lines we will use the CULL INDEX component.

We have 2 horizontal lines above each other. Both lines have eleven points. With the CULL INDEX component we will delete the last point of the lower horizontal line, the index input of the CULL INDEX component has to be 10. Next we will delete the first point of the upper horizontal line, the index input of the CULL INDEX component has to be 0. To set the INTEGER component connected to the CULL INDEX component on 0 and 10 RMB-click the component and go to change integer, see figure Change INTEGER component. Now we can create the diagonal lines by connecting both point lists to the LINE component.

Step 2 - Create Surfaces

To create the surfaces we want to copy the vertical and diagonal lines 0.8 in the Y-direction. In the Grasshopper start file the UNIT Y component and the 0.8 value PANEL Component are given. Use two MOVE components to copy and move the vertical and diagonal lines separately in the Y-direction. Connect the outputs of the LINE components to a GRAFT TREE component. This is needed to create correct Lofts, see figure for the list hierarchy. TIP: you can also graft the vertical and horizontal line parameter output. RMB click the L parameter and choose Graft. Now you don't need a separate GRAFT TREE component.

Connect the GRAFT TREE component and the UNIT Y component with the 0.8 value PANEL to the MOVE component for both vertical and diagonal lines. This will copy and move the lines in the Y-direction. Create surfaces between the lines by lofting the lines with the LOFT component. Connect both the GRAFT component and MOVE component output with the LOFT component.

Step 3 - Create round construction

In the Grasshopper start file you will find a MOVE component that creates a copy of the first horizontal line in the Y-direction with 0.4. This is the middle line for the round construction created with a PIPE component. Do the same for the upper horizontal line by adding this MOVE component output to the input of the other MOVE component, see figure.

The MOVE component copies the lines in the Y-direction with 0.4. But the UNIT Y component with the 0.8 value PANEL gives a input of 0.8. This means that the input T (Motion) is being divided by two by a Expression (T/2). RMB-click the T parameter input to find the Expression tab, see figure. TIP: You can also create a DIVISION component to divide the UNIT Y component output by two.

Create a PIPE component to create the round construction for the two horizontal lines. The radius has to be 0.4.