Minecraft_Cubes

• Grass
• Taiga
• Dirt
• Diorite
• Sand
• Cloud
• Water

This is a relatively simple CityEngine rule that is a good starting point for learning the Computer Generated Architecture (CGA) language used by CityEngine. Refer to the annotated CGA code below to see the different parts:

1. Biome Attribute. The Biome attribute is defined, with a default value of “Grass”. When the RPK is applied in Pro, it will look for this attribute (and the 7 unique biome values) in the point feature class.
2. Rule Parameters. Additional user-adjustable parameters are defined. This will expose the option to change the opacity/transparency of the cloud or water cubes. By default, they have a value of 1.0 and all cubes are fully opaque (no transparency).
3. Texture Library. The textures to use for each biome type are defined and stored in a folder in the rule.
4. Primitive Cube Start Rule. All CGA begins with a Start Rule. This is the first branch of the tree and where the CGA logic begins. From the start rule, additional branches of rules are attached. The @StartRule annotation above the rule logic indicates this is the start rule, and @InPoint defines that a point feature class is the expected input.
5. Top / Side / Bottom Textures sub-Rules. These branch off the Start Rule and apply the appropriate textures to each face of the primitive cube, according to the textures defined in the library. and the sides of the cube: TopFace, SideFace, and BottomFace.

这是一个相对简单的CityEngine规则，是学习CityEngin使用的计算机生成体系结构（CGA）语言的良好起点。请参阅下面带注释的CGA代码，以查看不同的部分：
生物特征。Biome属性已定义，默认值为“Grass”。在Pro中应用RPK时，它将在点要素类中查找该属性（以及7个唯一的生物群落值）。
规则参数。定义了其他用户可调参数。这将显示更改云或水立方的不透明度/透明度的选项。默认情况下，它们的值为1.0，并且所有立方体都是完全不透明的（没有透明度）。
纹理库。每个生物群落类型使用的纹理都已定义并存储在规则中的文件夹中。
基本多维数据集开始规则。所有CGA都以开始规则开始。这是树的第一个分支，也是CGA逻辑的起点。从开始规则开始，附加规则的其他分支。规则逻辑上方的@StartRule注释表示这是开始规则，@InPoint定义点要素类是预期输入。
顶部/侧面/底部纹理子规则。这些分支脱离了“开始规则”，并根据库中定义的纹理将适当的纹理应用于基本体立方体的每个面。以及立方体的侧面：TopFace、SideFace和BottomFace。

 

CityEngine-authored Rule Packages (*.rpk) are just zip files, so it’s actually possible to make small changes to the CGA logic or texture library even if you don’t have CityEngine installed — but are familiar with the syntax. After unzipping the Minecraft_Cubes.rpk, you will see this file structure:

CityEngine编写的规则包（*.rpk）只是zip文件，因此即使您没有安装CityEngin，也可以对CGA逻辑或纹理库进行小的更改，但您熟悉语法。解压缩Minecraft_Cubes后。rpk，您将看到以下文件结构：

Inside the assets folder, you will find the texture files for each biome cube, and in the rules folder you will find the Minecraft_Cubes.cga which you can open and alter in a text editor. Once you’ve made your changes, simply zip the folders back up and change the .zip extension to .rpk, then apply it to your points in ArcGIS Pro.

Some simple CGA code changes you can experiment with:

• Replace the biome textures with your own versions. (the format used is .png, 160 x 160 pixels) Remember to keep the file names and locations the same, or else you will also have to update the texture file names in the Texture Library Section of the CGA.
• Change the default cloud or texture opacity (waterOpacityValue or cloudOpacityValue) in the Rule Parameters section of the CGA from 1.0 (opaque) to something partially-transparent (e.g., 0.5).
• For a bigger challenge, try adding additional Biome types to the CGA by following/duplicating the existing code logic.