What Is the File Extension VTF?
- VTF textures must have dimensions equal to powers of two. For example, an image 512 x 256 pixels is acceptable while an image 100 x 200 is not. Increasing by powers of two, textures can have dimensions up to 4096 pixels in length.
- VTFs support a wide variety of image formats. Most will not be used by a developer. All of the image formats are explained on Valve's developer wiki (see References). Common DXT formats for textures that include alpha channels and BGR for normal maps. Normal maps are standard textures not used for a particular effect, such as a brick pattern on a wall, while textures with alpha channels are usually used to create bump mapping giving the appearance of a physical surface texture within games.
- The VTFs created by Valve are supplied with their games and can be extracted for use by developers. Large compressed files called GCFs store the textures and third-party tools like Nem's GCFScape (see References) are required to extract them. With Valve's VTFs extracted, you can modify them or look at them to learn how Valve constructs and uses textures within the Source engine.
- VTFs are not readable by default in image editors like Adobe Photoshop. Nemesis has also created a plugin for Photoshop along with a program called VTFEdit to allow anyone to view, create and edit VTFs. The Photoshop plugin is simple compared to VTFEdit, which allows you to edit more characteristics of VTF files such as shading effects and other filters used by the Source engine.
- VTFs are not used by themselves in Hammer, Valve's 3D level creation program. Remember that all VTFs are associated with Valve Material Types, which can be displayed in game levels and within the Hammer editor during the texturing of a level. The VMTs control the in-game behavior of material and lighting effects, such as whether a surface acts like wood or metal, while VTFs can be thought of as the paint that goes onto the surface. Before you try to use VTFs make sure they are associated with VMTs to import into Hammer.