terrain-flat-mask render plugin

A terrain mask render plugin that flattens the terrain inside a given area into a plane on layers with terrain.

The terrain-flat-mask render plugin generates a terrain mask from polygon data: it draws a plane over the masked area. Combined with the fill render plugin (draw the fill first, then the mask), it can achieve terrain excavation and flattening effects. The mask plane is drawn at the feature's own altitude by default, and its height can be adjusted with the dataConfig altitudeOffset.

Note: this plugin only acts as a terrain mask when the layer has the awareOfTerrain option enabled (TerrainFlatMaskPainter.isTerrainMask returns layer.options.awareOfTerrain in the source code).

Configuration

{
  // [必填] 渲染插件对象
  renderPlugin: {
    // [必填] 插件类型，固定为terrain-flat-mask
    type: "terrain-flat-mask",
    // [必填] 数据配置
    dataConfig: {
      // [必填] 数据类型，固定为fill
      type: "fill",
      // [可选] 默认为0，单位米
      // 遮罩平面的垂直偏移高度
      altitudeOffset: 3500
    },
    // [可选] 默认为null
    // 渲染场景配置
    sceneConfig: {
      // [Optional] Default: "one"
      // The src parameter of the WebGL blendEquation; possible values:
      // 0, 1, "src color", "one minus src color", "src alpha", "one minus dst color", "dst alpha",
      // "one minus dst alpha", "constant color", "one minus constant color", "constant alpha",
      // "one minus constant alpha", "src alpha saturate"
      blendSrc: "one",
      // [Optional] Default: "one minus src alpha"
      // The dst parameter of the WebGL blendEquation; possible values:
      // 0, 1, "src color", "one minus src color", "src alpha", "one minus dst color", "dst alpha",
      // "one minus dst alpha", "constant color", "one minus constant color", "constant alpha",
      // "one minus constant alpha", "src alpha saturate"
      blendDst: "one minus src alpha",
      // [Optional] Default: [0, 1]
      // The WebGL depth value range
      depthRange: [0, 1],
      // [Optional] Default: null
      // A feature-filter expression; data matching the condition will not be rendered
      excludes: null

      // [可选] 默认为[0, 1]
      // WebGL深度值范围
      depthRange: [0, 1]
    }
  },
  // [可选] 默认为true
  // 数据过滤条件
  filter: true,
  // 样式属性
  symbol: {}
}

For more on the filter data filtering conditions, see feature-filter.

Supported data types

• For vector tile data, Features with a type of Polygon or MultiPolygon are supported
• For GeoJSON data, Features with a type of Polygon or MultiPolygon are supported
• For vector layers, maptalks.Polygon, maptalks.MultiPolygon are supported.

Supported Symbol style properties

The terrain-flat-mask render plugin has no symbol style properties; symbol can be set to an empty object {}.

This document has been cross-checked against the @maptalks/gl-layers 2026 source code (api-notes-others.md)