port from perforce

hgplus/ShaderMinifier/tests/real/to_the_road_of_ribbon.frag

@@ -0,0 +1,64 @@
+uniform vec2 resolution;
+uniform float time;
+
+//Object A (tunnel)
+float oa(vec3 q)
+{
+ return cos(q.x)+cos(q.y*1.5)+cos(q.z)+cos(q.y*20.)*.05;
+}
+
+//Object B (ribbon)
+float ob(vec3 q)
+{
+ return length(max(abs(q-vec3(cos(q.z*1.5)*.3,-.5+cos(q.z)*.2,.0))-vec3(.125,.02,time+3.),vec3(.0)));
+}
+
+//Scene
+float o(vec3 q)
+{
+ return min(oa(q),ob(q));
+}
+
+//Get Normal
+vec3 gn(vec3 q)
+{
+ vec3 f=vec3(.01,0,0);
+ return normalize(vec3(o(q+f.xyy),o(q+f.yxy),o(q+f.yyx)));
+}
+
+//MainLoop
+void main(void)
+{
+ vec2 p = -1.0 + 2.0 * gl_FragCoord.xy / resolution.xy;
+ p.x *= resolution.x/resolution.y;
+ 
+ vec4 c=vec4(1.0);
+ vec3 org=vec3(sin(time)*.5,cos(time*.5)*.25+.25,time),dir=normalize(vec3(p.x*1.6,p.y,1.0)),q=org,pp;
+ float d=.0;
+
+ //First raymarching
+ for(int i=0;i<64;i++)
+ {
+  d=o(q);
+  q+=d*dir;
+ }
+ pp=q;
+ float f=length(q-org)*0.02;
+
+ //Second raymarching (reflection)
+ dir=reflect(dir,gn(q));
+ q+=dir;
+ for(int i=0;i<64;i++)
+ {
+ d=o(q);
+ q+=d*dir;
+ }
+ c=max(dot(gn(q),vec3(.1,.1,.0)),.0)+vec4(.3,cos(time*.5)*.5+.5,sin(time*.5)*.5+.5,1.)*min(length(q-org)*.04,1.);
+
+ //Ribbon Color
+ if(oa(pp)>ob(pp))c=mix(c,vec4(cos(time*.3)*.5+.5,cos(time*.2)*.5+.5,sin(time*.3)*.5+.5,1.),.3);
+
+ //Final Color
+ vec4 fcolor = ((c+vec4(f))+(1.-min(pp.y+1.9,1.))*vec4(1.,.8,.7,1.))*min(time*.5,1.);
+ gl_FragColor=vec4(fcolor.xyz,1.0);
+}