Returns the number of varying values that can be used in shaders on the current device. Varyings are the variables that pass data between the vertex and pixel shaders. This value is guaranteed to be at least 32, but most devices support more. A single vec4 varying holds 4 varying values, so 32 varyings values means you can have a maximum of 8 vec4 varyings. Note that a vec3 varying may take up 4 value spaces if it cannot be packed with any other varying. Varyings will automatically be packed together if they can fill a vec4 without being split, for example a vec3 and a float can be packed together, as can two vec2 varyings. However two vec3 varyings cannot be packed together without being split up so they will each use up 4 values with the extra space being wasted.