-- GLSL.Vert --

#version 120

uniform float u_Time;

attribute vec2 in_Position;

varying vec2 pass_Position;
varying mat2 pass_Rotation;
varying vec3 water[4];
varying vec3 fire[4];

float mod289(float x)
{
    return x - floor(x * (1.0 / 289.0)) * 289.0;
}

void main(void)
{
    mat3 r = mat3(0.36, 0.48, -0.8, -0.8, 0.60, 0.0, 0.48, 0.64, 0.60);
    vec3 p_pos = r * vec3(in_Position * vec2(16.0, 9.0), 0.0);
    vec3 p_time = r * vec3(0.0, 0.0, u_Time * 2.0);

    /* Noise sampling points for water */
    water[0] = p_pos / 2.0 + p_time;
    water[1] = p_pos / 4.0 + p_time;
    water[2] = p_pos / 8.0 + p_time;
    water[3] = p_pos / 16.0 + p_time;

    /* Noise sampling points for fire */
    p_pos = 16.0 * p_pos - r * vec3(0.0, mod289(u_Time) * 128.0, 0.0);
    fire[0] = p_pos / 2.0 + p_time;
    fire[1] = p_pos / 4.0 + p_time;
    fire[2] = p_pos / 8.0 + p_time;
    fire[3] = p_pos / 16.0 + p_time;

    pass_Position = in_Position;
    pass_Rotation = mat2(cos(u_Time), sin(u_Time), -sin(u_Time), cos(u_Time));

    gl_Position = vec4(in_Position, 0.0, 1.0);
}

-- GLSL.Frag --

#version 120

uniform float u_Time;

varying vec2 pass_Position;
varying mat2 pass_Rotation;
varying vec3 water[4];
varying vec3 fire[4];

vec4 mod289(vec4 x)
{
    return x - floor(x * (1.0 / 289.0)) * 289.0;
}

vec4 perm(vec4 x)
{
    return mod289(((x * 34.0) + 1.0) * x);
}

float noise3d(vec3 p)
{
    vec3 a = floor(p);
    vec3 d = p - a;
    d = d * d * (3.0 - 2.0 * d);

    vec4 b = a.xxyy + vec4(0.0, 1.0, 0.0, 1.0);
    vec4 k1 = perm(b.xyxy);
    vec4 k2 = perm(k1.xyxy + b.zzww);

    vec4 c = k2 + a.zzzz;
    vec4 k3 = perm(c);
    vec4 k4 = perm(c + 1.0);

    vec4 o1 = fract(k3 * (1.0 / 41.0));
    vec4 o2 = fract(k4 * (1.0 / 41.0));

    vec4 o3 = o2 * d.z + o1 * (1.0 - d.z);
    vec2 o4 = o3.yw * d.x + o3.xz * (1.0 - d.x);

    return o4.y * d.y + o4.x * (1.0 - d.y);
}

void main(void)
{
    vec2 tmp = pass_Rotation * pass_Position;
    float test = tmp.x * tmp.y + sin(3.0 * u_Time);

    /* Add some garbage noise */
    test += fract(sin(test * 938.437) * 137.0) / 2.0;

    vec3 points[4] = (test > 0.0) ? fire : water;

    vec4 n = vec4(noise3d(points[0]),
                  noise3d(points[1]),
                  noise3d(points[2]),
                  noise3d(points[3]));

    vec4 color;

    if (test > 0.0)
    {
        float p = dot(n, vec4(0.125, 0.125, 0.25, 0.5));

        /* Fade out by adding [-.5,.5] */
        p -= pass_Position.y * 0.8 + 0.25;
        p = max(p, 0.0);
        p = min(p, 1.0);

        float q = p * p * (3.0 - 2.0 * p);
        float r = q * q * (3.0 - 2.0 * q);
        color = vec4(min(q * 2.0, 1.0),
                     max(r * 1.5 - 0.5, 0.0),
                     max(q * 8.0 - 7.3, 0.0),
                     1.0);
    }
    else
    {
        float p = dot(abs(2.0 * n - 1.0),
                      vec4(0.5, 0.25, 0.125, 0.125));
        float q = sqrt(p);

        color = vec4(1.0 - q,
                     1.0 - 0.5 * q,
                     1.0,
                     1.0);
    }

    gl_FragColor = color;
}

-- HLSL.Vert --

void main(float2 in_Position : POSITION,
          uniform float2 u_WinSize,
          out float4 out_Position : POSITION,
          out float2 pass_Position : TEXCOORD0)
{
    //pass_Position = in_Position * u_WinSize;
    pass_Position = in_Position * float2(1280.0, 720.0);
    out_Position = float4(in_Position, 0.0, 1.0);
}

-- HLSL.Frag --

float4 mod289(float4 x)
{
    return x - floor(x * (1.0 / 289.0)) * 289.0;
}

float4 perm(float4 x)
{
    return mod289(((x * 34.0) + 1.0) * x);
}

float noise3d(float3 p)
{
    float3x3 r = float3x3(0.36, 0.48, -0.8, -0.8, 0.60, 0.0, 0.48, 0.64, 0.60);
    p = mul(r, p);

    float3 a = floor(p);
    float3 d = p - a;
    d = d * d * (3.0 - 2.0 * d);

    float4 b = a.xxyy + float4(0.0, 1.0, 0.0, 1.0);
    float4 k1 = perm(b.xyxy);
    float4 k2 = perm(k1.xyxy + b.zzww);

    float4 c = k2 + a.zzzz;
    float4 k3 = perm(c);
    float4 k4 = perm(c + 1.0);

    float4 o1 = frac(k3 * (1.0 / 41.0));
    float4 o2 = frac(k4 * (1.0 / 41.0));

    float4 o3 = o2 * d.z + o1 * (1.0 - d.z);
    float2 o4 = o3.yw * d.x + o3.xz * (1.0 - d.x);

    return o4.y * d.y + o4.x * (1.0 - d.y);
}

void main(in float2 pass_Position : TEXCOORD0,
          uniform float u_Time,
          out float4 out_FragColor : COLOR)
{
    float2 xy = pass_Position;
    float z = u_Time * 2.0;

    float tx = pass_Position.x * cos(u_Time) - pass_Position.y * sin(u_Time);
    float ty = pass_Position.x * sin(u_Time) + pass_Position.y * cos(u_Time);

    if (tx * ty > 0.0)
        xy.y -= z * 200.0;

    float p1 = noise3d(float3(xy / 80.0, z));
    float p2 = noise3d(float3(xy / 40.0, z));
    float p3 = noise3d(float3(xy / 20.0, z));
    float p4 = noise3d(float3(xy / 10.0, z));

    float4 color;

    if (tx * ty > 0.0)
    {
        float p = 0.5 * p1 + 0.25 * p2 + 0.125 * (p3 + p4);

        /* Scroll by adding [-.5,.5] */
        p -= pass_Position.y / 1440.0;
        p = max(p, 0.0);
        p = min(p, 1.0);

        float q = p * p * (3.0 - 2.0 * p);
        float r = q * q * (3.0 - 2.0 * q);
        color = float4(min(q * 2.0, 1.0),
                       max(r * 1.5 - 0.5, 0.0),
                       max(q * 8.0 - 7.3, 0.0),
                       1.0);
    }
    else
    {
        float p = 0.5 * p1 + 0.25 * p2 + 0.125 * (p3 + p4);

        float q = p * p * (3.0 - 2.0 * p);
        float r = q * q * (3.0 - 2.0 * q);
        color = float4(1.0 - q,
                       1.0 - 0.5 * r,
                       1.0,
                       1.0);
    }

    out_FragColor = color;
}