Texture Info

Textures are images applied to polygons to make more realistic appearance without increased polygon count. The images can be created with almost any image editing or painting software. Examples:

• Adobe Photoshop, Photoshop LE or Photoshop Elements
• Ulead PhotoImpact
• GNU Image Manipulation Program (The Gimp) http://www.gimp.org/

Many types of image are supported by the osgDB::Image library; my preferred formats are:

• jpeg - high quality images with good compression
• tga - widely available in image editors
• png - lower colour resolution, but supports Transparent Images.

I rarely use BMP as file sizes are large (bigger than NX by NY pixels times 3 bytes for an RGB image).

Most (?all?) OpenGL implementations convert the image loaded to a power of 2 size (eg a 324 by 133 pixel image will often be rounded to 256 by 128 pixels). Therefore it is useful to produce your textures in power of 2 sizes so that all users will see the same appearance, and no re-interpolation is carried out by the end program.

Often a texture is repeated to obtain higher texel count when viewed closely - a method of generating repeating textures that do not show sharp discontinuities is described in Making Repeating Textures