**CGA OPERATIONS COVERED**

r()- rotate s()- size t()- translate

**INTRODUCTION**

The **rotate r( ), size s ( )** and **translate t( )** shape functions are neighbors in the alphabet and they are used with each other to manipulate scopes, the imaginary box that surrounds a shape and defines its maximum x, y and z dimensions.

It will be important to know these before we start shaping buildings and modeling facades in Tutorials 6 and 7.

**Rotate:** In Figure A, a flat plane is rotated 45 degrees on it’s x, y and z axes, which are indicated with blue lines. The parameters for the three planes are: x-axis r(45,0,0); y-axis r(0,45,0); z-axis r(0,0,45). The planes can also be rotated in the opposite directions using negative values.

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**Size:** Here, we will resize shapes by adjusting their scope. When we change the x, y and/or z dimensions of the scope, whatever shape is inside will change dimensions. Each primitive cone starts with 12 sides, a diameter of 20 meters and a height of 40 meters as shown in the code block. See what happens as we resize the x, y or z of each shape’s scope: Increasing x or z makes as in Cones 2 & 3 widens them in one direction. Increasing y makes Cone 4 taller. Giving z a value of 1 actually flattens Cone 5. Depending on the adjustment to the scope, the shape may have to be translated (moved) to its desired position on the landscape.

StartCone --> primitiveCone(12,20,40) color("#FFFF00") # Resize X Cone2--> primitiveCone(12,20,40) color("#FFFF00") s(70,20,20) # Resize Z Cone3 --> primitiveCone(12,20,40) color("#FFFF00") s(20,20,70) # Resize Y Cone4 --> primitiveCone(12,20,40) color("#FFFF00") s(20,80,20) # Flatten Z Cone5 --> primitiveCone(12,20,40) color("#FFFF00") s(20,20,1))

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**Translate:** We will move a 10×10 meter flat plane along the x, y and z axes.

- The yellow square represents the starting coordinates of t(0,0,0).
- Red: t(20,0,0) – movement along the x-axis
- Green: t(0,10,0) – movement along the y-axis (straight up)
- Blue: t(0,0,20) – movement along the z-axis

Start--> primitiveQuad(10,10) color("#FFFF00") // Yellow t(0,0,0) Start2--> primitiveQuad(10,10) color("#FF0000") // Red t(20,0,0) Start3--> primitiveQuad(10,10) color("#00FF00") // Green t(0,10,0) Start4--> primitiveQuad(10,10) color("#0000FF") // Blue t(0,0,20)