#ifndef __SHADER_INCLUDES__
#define __SHADER_INCLUDES__

// Struct representing the data we expect to receive from earlier pipeline stages
// - Should match the output of our corresponding vertex shader
// - The name of the struct itself is unimportant
// - The variable names don't have to match other shaders (just the semantics)
// - Each variable must have a semantic, which defines its usage
struct VertexToPixel
{
	// Data type
	//  |
	//  |   Name          Semantic
	//  |    |                |
	//  v    v                v
	float4 screenPosition	: SV_POSITION;
	float2 uv				: TEXCOORD;
};

// Struct representing a single vertex worth of data
// - This should match the vertex definition in our C++ code
// - By "match", I mean the size, order and number of members
// - The name of the struct itself is unimportant, but should be descriptive
// - Each variable must have a semantic, which defines its usage
struct VertexShaderInput
{
    // Data type
    //  |
    //  |   Name          Semantic
    //  |    |                |
    //  v    v                v
    float3 localPosition	: POSITION;
    float3 normal			: NORMAL;
    float2 uv				: UV;
};

/// BEGIN THIRD PARTY ///
/// SOURCE: https://thebookofshaders.com/edit.php#11/2d-snoise-clear.frag ///

// Some useful functions
float3 mod289(float3 x) { return x - floor(x * (1.0 / 289.0)) * 289.0; }
float2 mod289(float2 x) { return x - floor(x * (1.0 / 289.0)) * 289.0; }
float3 permute(float3 x) { return mod289(((x * 34.0) + 1.0) * x); }

//
// Description : GLSL 2D simplex noise function
//      Author : Ian McEwan, Ashima Arts
//  Maintainer : ijm
//     Lastmod : 20110822 (ijm)
//     License :
//  Copyright (C) 2011 Ashima Arts. All rights reserved.
//  Distributed under the MIT License. See LICENSE file.
//  https://github.com/ashima/webgl-noise
//
float snoise(float2 v)
{
    // Precompute values for skewed triangular grid
    const float4 C = float4(0.211324865405187,
        // (3.0-sqrt(3.0))/6.0
        0.366025403784439,
        // 0.5*(sqrt(3.0)-1.0)
        -0.577350269189626,
        // -1.0 + 2.0 * C.x
        0.024390243902439);
    // 1.0 / 41.0

    // First corner (x0)
    float2 i = floor(v + dot(v, C.yy));
    float2 x0 = v - i + dot(i, C.xx);

    // Other two corners (x1, x2)
    float2 i1 = float2(0, 0);
    i1 = (x0.x > x0.y) ? float2(1.0, 0.0) : float2(0.0, 1.0);
    float2 x1 = x0.xy + C.xx - i1;
    float2 x2 = x0.xy + C.zz;

    // Do some permutations to avoid
    // truncation effects in permutation
    i = mod289(i);
    float3 p = permute(
        permute(i.y + float3(0.0, i1.y, 1.0))
        + i.x + float3(0.0, i1.x, 1.0));

    float3 m = max(0.5 - float3(
        dot(x0, x0),
        dot(x1, x1),
        dot(x2, x2)
        ), 0.0);

    m = m * m;
    m = m * m;

    // Gradients:
    //  41 pts uniformly over a line, mapped onto a diamond
    //  The ring size 17*17 = 289 is close to a multiple
    //      of 41 (41*7 = 287)

    float3 x = 2.0 * frac(p * C.www) - 1.0;
    float3 h = abs(x) - 0.5;
    float3 ox = floor(x + 0.5);
    float3 a0 = x - ox;

    // Normalise gradients implicitly by scaling m
    // Approximation of: m *= inversesqrt(a0*a0 + h*h);
    m *= 1.79284291400159 - 0.85373472095314 * (a0 * a0 + h * h);

    // Compute final noise value at P
    float3 g = float3(0, 0, 0);
    g.x = a0.x * x0.x + h.x * x0.y;
    g.yz = a0.yz * float2(x1.x, x2.x) + h.yz * float2(x1.y, x2.y);
    return 130.0 * dot(m, g);
}

/// SOURCE: https://thebookofshaders.com/10/ ///
float random(float2 st)
{
    return frac(sin(dot(st.xy,
        float2(12.9898, 78.233))) *
        43758.5453123);
}

/// END THIRD PARTY ///

#endif