ESSL—OpenGL ES Shading Language

OpenGL ES Shading Language (ESSL) is the language in which we write our shaders. Its syntax and semantics are very similar to C/C++. However, it has types and built-in functions that make it easier and more intuitive to manipulate vectors and matrices. In this section, we will cover the basics of ESSL so we can start using it right away.

Note

This section is a summary of the official GLSL ES specification. It is a subset of GLSL (the shading language for OpenGL).

You can find the complete reference at http://www.khronos.org/registry/gles/specs/2.0/GLSL_ES_Specification_1.0.17.pdf

Storage qualifier

Variable declarations may have a storage qualifier specified in front of the type:

• attribute: Linkage between a vertex shader and a WebGL application for per-vertex data. This storage qualifier is only legal inside the vertex shader.

• uniform: Value does not change across the object being processed, and uniforms form the linkage between a shader and a WebGL application...