Snow rotate-o

crok_snow3d.glsl

// based on https://www.shadertoy.com/view/4tSSzt by FabriceNeyret2
// using the base ray-marcher of Trisomie21: https://www.shadertoy.com/view/4tfGRB#

vec3 adsk_getVertexPosition();
vec3 adsk_getCameraPosition();
vec3 adsk_getLightPosition();
vec3 adsk_getLightDirection();
vec3 adsk_getLightTangent();
vec3 adsk_getLightColour();
vec3 adsk_getDiffuseMapCoord();
vec4 adsk_getDiffuseMapValue(in vec2 texCoord);

float adsk_getTime();

uniform float adskUID_Speed;
uniform float adskUID_Offset;
uniform float amount, pp1, pp2;
uniform vec3 speed;

vec2 adskUID_resolution = vec2(1920., 1080.);

float adskUID_time = adsk_getTime() * 0.05 * adskUID_Speed + adskUID_Offset;

#define r(v,t) v *= mat2( C = cos((t)*adskUID_time), S = sin((t)*adskUID_time), -S, C )

float smin( float a, float b )
{
    return min(a,b);
}

vec4 adskUID_lightbox(vec4 source)
{
	vec3 uv = adsk_getDiffuseMapCoord();
    vec3 camera = adsk_getCameraPosition();
    vec3 vertex = adsk_getVertexPosition();
    vec3 light = adsk_getLightPosition();
    vec3 lightdir = adsk_getLightDirection();
    vec3 lighttan = adsk_getLightTangent();
    vec3 lightbitan = cross(lightdir, lighttan);
    mat3 lightbasis = mat3(lighttan, -lightbitan, lightdir);
    vec3 dir = normalize(vertex - camera);
    vec3 ro = camera  - light;
    ro *= lightbasis;
	ro /= 100.;
	vec3 rd = dir * lightbasis;
    //ro += rd;
		
	vec2 w = uv.xy;
	vec4 f = vec4(0.0);
	
    float C,S,r,r1,x,x1,i0;
    vec4 p = vec4(w,0,1)/adskUID_resolution.yyxy-.5, d,p2, u,t,t1,M,m; p.x-=.4; // init ray 
         
    //r(p.xz,.13); r(p.yz,.2); r(p.xy,.1);   // camera rotations
    d.xyz = rd;                                 // ray dir = ray0-vec3(0)
    p.xyz = -ro;
    p.xyz += adskUID_time * speed;
	
   
    for (float i=1. * amount; i>0.; i-=.01)  
    { x = 1e3;
     for(float j=0.; j<=1.; j++) {
        u = floor(p/8.+11.5*j);                 // objects id + local frame
        u = fract(1234.*sin(78.*(u+u.yzxw)));         // randomize ids
        
        p2 = p+11.5*j; 
         if (j==0.) p2.x -= 15.*adskUID_time*(2.*u.y-1.);            // offset column
         else       p2.y -= 15.*adskUID_time*(2.*u.z-1.);    
        u = floor(p2/8.); t = mod(p2, 8.)-4.;
        u = fract(1234.*sin(78.*(u+u.yzxw)*vec4(1,-12,8,-4)));
        
              
        r = .17*pp1 + 0.1 *pp2 * u.w; 
		r1 =3.15;
        t1 = t+r1*sin(1.*adskUID_time+u*6.);               x1 = length(t .xyz)-r;    x = smin(x,x1);
        t1 = t+r1*sin(2.*adskUID_time-u*6.); r(t1.xy,u.z); x1 = length(t1.xyz)-r*.8; x = smin(x,x1);
        t1 = t+r1*sin(3.*adskUID_time+u*3.); r(t1.yz,u.x); x1 = length(t1.xyz)-r*.5; x = smin(x,x1);
        if(x<.01) break;   // hit !
      }
    
        if(x<.01) {i0=i; break; }  // hit !
    
        p -= d*x;           // march ray
     }
    if(x<.01)  // hit !
		{
			f = i0*i0*(t);
		} // color texture + black fog 
		
		return vec4(f.rrr, source.a);
	}