Clamp Texture Address Mode
The clamp texture address mode, identified by the TextureAddress.Clamp enumerated value, causes Microsoft Direct3D to clamp texture coordinates to the [0.0, 1.0] range. That is, it applies the texture once, and then smears the color of edge pixels.
For example, suppose that an application creates a square primitive and assigns texture coordinates of (0.0,0.0), (0.0,3.0), (3.0,3.0), and (3.0,0.0) to the primitive's vertices. Setting the texture address mode to TextureAddress.Clamp results in the texture being applied once. The pixel colors at the top of the columns and the end of the rows are extended to the top and right of the primitive respectively, as shown in the following illustration.