デモシーン14

#define PI 3.14159265359

//----------------------------------------------------------------------
//ノイズ関連

// 2Dランダム関数
float random(vec2 st) {
    return fract(sin(dot(st.xy, vec2(12.9898,78.233))) * 43758.5453123);
}

// 2Dノイズ関数
float noise(vec2 st) {
    vec2 i = floor(st);
    vec2 f = fract(st);

    // 4つの隅の乱数値を取得
    float a = random(i);
    float b = random(i + vec2(1.0, 0.0));
    float c = random(i + vec2(0.0, 1.0));
    float d = random(i + vec2(1.0, 1.0));

    // スムーズステップによる補間
    vec2 u = f * f * (3.0 - 5.0 * f);

    return mix(a, b, u.x) +
           (c - a) * u.y * (1.0 - u.x) +
           (d - b) * u.x * u.y;
}

// フラクタルブラウン運動（fBm）関数
float fbm(vec2 st) {
    float value = 0.0;
    float amplitude = 0.5;  // 振幅

    for (int i = 0; i < 60; i++) {
        value += amplitude * noise(st);
        st *= 2.0;
        amplitude *= 0.5;
    }
    return value;
}

//----------------------------------------------------------------------

mat2 rot(float a) {
    return mat2(cos(a), -sin(a), sin(a), cos(a));
}

//----------------------------------------------------------------------
//平面
float sdPlane(vec3 p, vec3 n, float h)
{
    return dot(p, n) + h;
}
//----------------------------------------------------------------------

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    vec2 uv = (fragCoord.xy * 2.0 - iResolution.xy) / iResolution.y;
    vec2 m = (iMouse.xy * 2.0 - iResolution.xy) / iResolution.y;

    vec3 ro = vec3(0.0, 0.0, -3.0);
    vec3 rd = normalize(vec3(uv, 1.0));

    ro.xz *= rot(iTime * PI / 4.);
    rd.xz *= rot(iTime * PI / 4.);

    ro.xz *= rot(-m.x);
    rd.xz *= rot(-m.x);

    ro.yz *= rot(-m.y);
    rd.yz *= rot(-m.y);

    vec3 totalColor = vec3(0.0);
    vec3 color = vec3(0.0);

    vec3 noiseColor = vec3(fbm(uv * 10.));
    vec3 noiseColor2 = vec3(fbm(uv * 10.),0.0, 0.5 + sin(iTime * PI) * 0.5);

    float t = 0.0;
    float d = 0.0;

    for (int i = 0; i < 64; i++)
    {
        vec3 p = ro + t * rd;
        float panel = sdPlane(p, vec3(0.0, 0.0, -1.0), noiseColor.y * 3.);
        d = panel;

        if (d < 0.01)
        {
            color = vec3(t * .1);
            totalColor += color;
            break;
        }
        if(t > 10.0)
        {
            totalColor += noiseColor2;
            break;
        }
        t += d;
    }
    fragColor = vec4(totalColor, 1.0);
}