Howto:Shader programming in FlightGear: Difference between revisions

Howto:Shader programming in FlightGear (view source)

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 User defined functions are supported, and a wide variety of commonly used functions are provided built-in as well. This allows the graphics card manufacturer the ability to optimize these built-in functions at the hardware level if they are inclined to do so. Many of these functions are similar to those found in the math library of the C programming language such as exp() and abs() while others are specific to graphics programming such as smoothstep() and texture2D().
-= GLSL Background =
-GLSL shaders are not stand-alone applications; they require an application that utilizes the OpenGL API.
-A shader is a program, to be run it must be loaded, compiled and linked. Actually each vertex and fragment shader must have one entry point (the main function) each, but you can create and link more shaders.
-GLSL shaders themselves are simply a set of strings that are passed to the hardware vendor’s driver for compilation from within an application using the OpenGL API’s entry points. Shaders can be created on the fly from within an application or read in as text files, but must be sent to the driver in the form of a string.
-GLSL has explicit ties to the OpenGL API - to the extent that much of the OpenGL 'state' (eg which light sources are bound, what material properties are currently set up) is presented as pre-defined global variables in GLSL.
 = Shader Types =