Applying a 2D texture

In GLSL, applying a texture to a surface involves accessing texture memory to retrieve a color associated with a texture coordinate, and then applying that color to the output fragment. The application of the color to the output fragment could involve mixing the color with the color produced by a shading model, simply applying the color directly, using the color in the reflection model, or some other mixing process. In GLSL, textures are accessed via sampler variables. A sampler variable is a "handle" to a texture unit. It is typically declared as a uniform variable within the shader and initialized within the main OpenGL application to point to the appropriate texture unit.

In this recipe, we'll look at a simple example involving the application of a 2D texture to a surface as shown in the following image. We'll use the texture color to scale the color provided by the ambient, diffuse, and specular (ADS) reflection model. The following image shows the results of a...