# GLSL Generator

Edit on GitHub

A GlslGenerator provides most syntax of what an OpenGL ES 2.0 shader would use. We can create functions, variables, if statements, and other built in functions directly. This page will be mostly examples for each of the major feature it offers. For more info on how to use this with shaders checkout the Shaders page.

## Usage

### Defining a Variable

We define can define variables by using delegates for each type of parameter we want to create. As well as passing in the variable type it expects as a parameter of the delegate.

// vertex
private val u_mat by uniform(::Mat4)
private val a_vec4 by attribute(::Vec4)
private val a_vec2 by attribute(::Vec3)
private var v_vec2 by varying(::Vec2)

// fragment
private val u_texture by uniform(::Sampler2D)


### Setting Precision

We can pass in an additional parameter of Precision when defining variables via delegates.

private val v_color by varying(::Vec4, Precision.LOW)


### Creating local variables

We can define variables via delegates or literally. Depending on the variable type, we can either add .lit to the end of it, such as for a Float, or Int.

init {
val result by vec2() // create new vec2 via delegate
result.x = 1f.lit // set x with literal float
result.y = 5f.lit // set y with literal float
gl_Position = vec4Lit(result, 42f, 1f) // generates "vec4(result, 42f, 1f);" in GLSL code.
}


### Creating Functions

We can define and use functions pretty similarly to how we define variables, via delegates and literals. We can make use of the Func delegate which expects the function return type and the types of any parameters it expects to be used in the function.

val returnFloat by Func(::FloatFunc, ::GLFloat) {
10f.lit + it // returns new float
}

init {
returnFloat(5f.lit)
}

val almostEqual by Func(::BoolFunc, ::GLFloat, ::GLFloat) { a, b ->
abs(a - b) lt 1e-5f
}

init {
almostEqual(0.01f.lit, 0.001f.lit)
}