Smoke1.shader

// 参考 : http://glslsandbox.com/e#37255.0
Shader "Smoke1"
{
    Properties
    {
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        Pass
        {
            CGPROGRAM
            #pragma vertex vert_img
            #pragma fragment frag
            
            #include "UnityCG.cginc"

            half random(half2 pos) 
            {
                return frac(sin(dot(pos.xy, half2(12.345, 23.456)))*1.2345);
            }

            half noise(half2 pos) 
            {
                half2 i = floor(pos);
                half2 f = frac(pos);
                half a = random(i + half2(0.0, 0.0));
                half b = random(i + half2(1.0, 0.0));
                half c = random(i + half2(0.0, 1.0));
                half d = random(i + half2(1.0, 1.0));
                half2 u = f * f * (3.0 - 2.0 * f);
                return lerp(a, b, u.x) + (c - a) * u.y * (1.0 - u.x) + (d - b) * u.x * u.y;
            }

            half fbm(half2 pos) 
            {
                half v = 0.0;
                half a = 0.58;

                half2x2 rot = half2x2(cos(0.5), sin(0.5), -sin(0.5), cos(0.5));

                for (int i=0; i < 10; i++) 
                {
                    v += a * noise(pos);
                    pos = mul(rot, pos)*2;
                    a *= 0.5;
                }
                return v;
            }

            half4 frag (v2f_img i) : SV_Target
            {
                half3 color = half3(0,0,0);
                half time = _Time * 30;
                half2 resolution = half2(2, 2);
                half2 p = (i.uv * 2.0 - resolution.xy) / min(resolution.x, resolution.y);

                half t = 0.0, d;
                half time2 = time /2;
                half2 q = half2(0, 0);
                q.x = fbm(p + half2(1.0,1.0) + 0.01 * time2);
                q.y = fbm(p + half2(1.0,1.0));
                half2 r = half2(0, 0);

                r.x = fbm(p + q + half2(1.7, 9.2) + 0.15 * time2);
                r.y = fbm(p + q + half2(8.3, 2.8) + 0.126 * time2);

                half f = fbm(p + r);

                color = lerp(
                    color,
                    half3(0.666667, 1, 1),
                    clamp(length(r.x), 0.0, 1.0)
                );

                color = (f *f * f + 0.6 * f * f + 0.5 * f) * color;

                return half4(color, 1.0);
            }
  
            ENDCG
        }
    }
}