This feature is utilized in a number of visualization approaches: triangles with individual textures for each vertex, which are interpolated during rendering.

Syntax:

MESH_TRIANGLE:
  triangle { 
    <Corner_1>,
    <Corner_2>,
    <Corner_3>
    [MESH_TEXTURE]
  }   |
  smooth_triangle { 
    <Corner_1>, <Normal_1>, 
    <Corner_2>, <Normal_2>, 
    <Corner_3>, <Normal_3> 
    [MESH_TEXTURE] 
  }

MESH_TEXTURE:
  texture { TEXTURE_IDENTIFIER } |
  texture_list {
    TEXTURE_IDENTIFIER TEXTURE_IDENTIFIER TEXTURE_IDENTIFIER
  }

To specify three vertex textures for the triangle, simply use texture_list instead of texture.

3.5.7 UV Mapping

3.5.8 Triangle Texture Interpolation

3.5.9 Interior Texture