Belts carry 4 grains deep; stalled belts warn and stop animating (t45)

src/render/gpu/smooth-shader.js

@@ -10,6 +10,7 @@ struct Params { view: vec4f, world: vec4f, style: vec4f, effects: vec4f, camera:
 @group(0) @binding(6) var tGlow: texture_2d<f32>;
 @group(0) @binding(7) var linear: sampler;
 @group(0) @binding(8) var<uniform> su: vec4f;
+@group(0) @binding(9) var tMotion: texture_2d<f32>;
 fn sampleLevel(t: texture_2d<f32>, uv: vec2f, level: f32) -> vec4f { return textureSampleLevel(t,linear,uv,level); }
 fn modulo(x: f32,y: f32) -> f32 { return x-y*floor(x/y); }
 fn h21(inputP: vec2f) -> f32 { var p=inputP; p = fract(p * vec2f(123.34, 456.21)); p += dot(p, p + 45.32); return fract(p.x * p.y); }
@@ -51,9 +52,9 @@ fn beltLineSD(c: vec2i, lb: vec2f) -> f32 {
   return beltSD(lb, (caps & 1) != 0, (caps & 2) != 0);
 }
 
-fn bandRidge(w: vec2f, lb: vec2f, dir: f32) -> f32 {
+fn bandRidge(w: vec2f, lb: vec2f, dir: f32, time: f32) -> f32 {
   var run: f32 = select( -1.0, 1.0 , lb.y < 2.0 );
-  return step(0.72, fract((w.x - dir * run * (su.x) * 30.0) * 0.5));
+  return step(0.72, fract((w.x - dir * run * time * 30.0) * 0.5));
 }
 fn bandColor(lb: vec2f, rg: f32) -> vec3f { return mix(vec3f(0.2, 0.21, 0.24), vec3f(0.34, 0.35, 0.39), rg) * (select( 0.72, 1.0 ,lb.y < 2.0 )); }
 
@@ -72,6 +73,7 @@ ${GPU_SMOOTH_SLOPE_HELPERS}
   var qq: vec2f = q - 0.5; var c0: vec2i = vec2i(floor(qq)); var t: vec2f = qq - floor(qq);
   var k0: vec4f = cellAt(tCol, c0); var k1: vec4f = cellAt(tCol, c0 + vec2i(1, 0)); var k2: vec4f = cellAt(tCol, c0 + vec2i(0, 1)); var k3: vec4f = cellAt(tCol, c0 + vec2i(1, 1));
   var n0: i32 = cls(k0); var n1: i32 = cls(k1); var n2: i32 = cls(k2); var n3: i32 = cls(k3);
+  let motionTime = cellAt(tMotion, c).r;
   var own: vec4f = cellAt(tCol, c); var nc: i32 = cls(own);
   var s: vec2f = smoothstep(vec2f(0.1), vec2f(0.9), t);
   var wq: vec4f = vec4f((1.0 - s.x) * (1.0 - s.y), s.x * (1.0 - s.y), (1.0 - s.x) * s.y, s.x * s.y);
@@ -228,14 +230,14 @@ ${GPU_SMOOTH_SLOPE_DRAW}
       var edge: f32 = -sd;
       var bc: vec3f;
       if (edge < 0.8) {
-        bc = bandColor(lb, bandRidge(w, lb, dir));
+        bc = bandColor(lb, bandRidge(w, lb, dir, motionTime));
         bc *= mix(0.55, 1.0, smoothstep(0.0, max(px * 1.4, 0.12), edge));
       } else {
         var rc: vec2f = vec2f(select( 3.0, 1.0 ,lb.x < 2.0 ), 2.0); var dv: vec2f = lb - rc;
         var rd: f32 = length(dv);
         bc = vec3f(0.15, 0.16, 0.18);
         if (rd < 0.95) {
-          var ang: f32 = atan2(dv.y, dv.x) - dir * (su.x) * 30.0 / 0.95;
+          var ang: f32 = atan2(dv.y, dv.x) - dir * motionTime * 30.0 / 0.95;
           var spoke: f32 = smoothstep(0.55, 0.85, cos(ang * 3.0));
           bc = mix(vec3f(0.5, 0.36, 0.25), vec3f(0.72, 0.53, 0.36), 0.5 + 0.5 * dot(normalize(dv + 1e-4), vec2f(-0.6, -0.8)) * smoothstep(0.2, 0.95, rd));
           bc *= mix(1.0, 0.72, spoke * smoothstep(0.25, 0.4, rd));
@@ -294,7 +296,7 @@ ${GPU_SMOOTH_SLOPE_DRAW}
       tc *= mix(0.5, 1.0, smoothstep(0.0, max(px * 1.3, 0.1), min(a, 4.0 - a)));
     } else {
       var full: bool = own.r + own.g + own.b > 0.0;
-      var fl: f32 = fract((along + a * 0.9 - sp2 * (su.x) * 14.0) * 0.5);
+      var fl: f32 = fract((along + a * 0.9 - sp2 * motionTime * 14.0) * 0.5);
       var flight: f32 = smoothstep(0.82, 0.92, fl) * (1.0 - smoothstep(0.92, 1.0, fl));
       var bore: vec3f = vec3f(0.11, 0.1, 0.11) * (0.8 + 0.4 * (1.0 - abs(a - 2.0) / 1.4));
       tc = select( bore, own.rgb * (0.9 + 0.1 * vn(w * 1.3)) ,full );
@@ -343,7 +345,7 @@ ${GPU_SMOOTH_SLOPE_DRAW}
       var hole: f32 = 1.0 - smoothstep(0.5 - bw2 - px, 0.5 - bw2, max(cg.x, cg.y));
       var fc: vec3f;
       if (edge < 0.8) {
-        var rg: f32 = bandRidge(w, lb, dir);
+        var rg: f32 = bandRidge(w, lb, dir, motionTime);
         var band: vec3f = bandColor(lb, rg);
         if (tinted && (carry == (lb.y < 2.0))) { band = mix(band, tag.rgb * (select( 0.8, 1.0 ,lb.y < 2.0 )), 0.75 * rg); }
         fc = mix(band, behind * 0.85, hole * (1.0 - rg) * 0.75);