8.12.3.45 IfcTextureVertex（纹理顶点）
8.12.3.45.1 语义定义（Semantic definition）
IfcTextureVertex 是一个包含 2 个 (S, T) 纹理坐标的列表。
Each vertex-based geometry node uses a set of 2D texture coordinates that map textures to vertices. Texture map values ( ImageTexture, PixelTexture) range from [0.0, 1.0] along the S-axis and T-axis. However, texture coordinate values may be in the range (-∞,∞). Texture coordinates identify a location (and thus a colour value) in the texture map. The horizontal coordinate S is specified first, followed by the vertical coordinate T. If the texture map is repeated in a given direction (S-axis or T-axis), a texture coordinate C (s or t) is mapped into a texture map that has N pixels in the given direction as follows:
纹理贴图位置 = (C - floor(C)) × NIf the texture map is not repeated, the texture coordinates are clamped to the 0.0 to 1.0 range as follows:
纹理贴图位置 = N, 如果 C > 1.0,
= 0.0, 如果 C < 0.0,
= C × N, 如果 0.0 ≤ C ≤ 1.0。
8.12.3.45.2 实体继承（Entity inheritance）
-
- IfcTextureVertex
- IfcColourRgbList
- IfcColourSpecification
- IfcCurveStyleFont
- IfcCurveStyleFontAndScaling
- IfcCurveStyleFontPattern
- IfcIndexedColourMap
- IfcPreDefinedItem
- IfcSurfaceStyleLighting
- IfcSurfaceStyleRefraction
- IfcSurfaceStyleShading
- IfcSurfaceStyleWithTextures
- IfcSurfaceTexture
- IfcTextStyleForDefinedFont
- IfcTextStyleTextModel
- IfcTextureCoordinate
- IfcTextureVertexList
8.12.3.45.3 特性（Attributes）
| # | 特性（Attributes） | 类型 | 描述 |
|---|---|---|---|
| IfcTextureVertex (1) | |||
| 1 | Coordinates | LIST [2:2] OF IfcParameterValue |
第一个坐标[1]是 S 参数值，第二个坐标[2]是 T 参数值。 |
8.12.3.45.4 形式化表示（Formal representation）
ENTITY IfcTextureVertex
SUBTYPE OF (IfcPresentationItem);
Coordinates : LIST [2:2] OF IfcParameterValue;
END_ENTITY;