optimize

frontend/src/assets/shader.glsl

@@ -1,16 +1,12 @@
 #version 300 es
-precision lowp float;
-uniform vec3 iResolution;           // viewport resolution (in pixels)
-uniform float iTime;                 // shader playback time (in seconds)
+precision mediump float;
+uniform vec3 iResolution;
+uniform float iTime;
 uniform sampler2D iChannel1;
 
 out vec4 FragColor;
 
-const float pi = 3.1415927f;
-
-float sdSphere(vec3 p, float s) {
-  return length(p) - s;
-}
+const float PI = 3.1415927f;
 
 float sdTorus(vec3 p, vec2 t) {
   vec2 q = vec2(length(p.xz) - t.x, p.y);
@@ -18,66 +14,87 @@ float sdTorus(vec3 p, vec2 t) {
 }
 
 void mainImage(out vec4 fragColor, in vec2 fragCoord) {
-  vec2 pp = fragCoord.xy / iResolution.xy;
-  pp = -1.0f + 2.0f * pp;
-  pp.x *= iResolution.x / iResolution.y;
+  vec2 uv = (fragCoord.xy / iResolution.xy) * 2.0f - 1.0f;
+  uv.x *= iResolution.x / iResolution.y;
 
+  // camera
   vec3 lookAt = vec3(0.0f, -0.1f, 0.0f);
-
   float eyer = 2.0f;
   float eyea = 0.0f;
-  float eyea2 = (-0.24f) * pi * 2.0f;
-
-  vec3 ro = vec3(eyer * cos(eyea) * sin(eyea2), eyer * cos(eyea2), eyer * sin(eyea) * sin(eyea2)); //camera position
+  float eyea2 = -0.24f * PI * 2.0f;
+  vec3 ro = vec3(eyer * cos(eyea) * sin(eyea2), eyer * cos(eyea2), eyer * sin(eyea) * sin(eyea2));
 
   vec3 front = normalize(lookAt - ro);
-  vec3 left = normalize(cross(normalize(vec3(0.0f, 1, -0.1f)), front));
+  vec3 left = normalize(cross(normalize(vec3(0.0f, 1.0f, -0.1f)), front));
   vec3 up = normalize(cross(front, left));
-  vec3 rd = normalize(front * 1.5f + left * pp.x + up * pp.y); // rect vector
+  vec3 rd = normalize(front * 1.5f + left * uv.x + up * uv.y);
 
-  vec3 bh = vec3(0.0f, 0.0f, 0.0f);
-  float bhr = 0.1f;
-  float bhmass = 5.0f;
-  bhmass *= 0.001f; // premul G
+  // black hole
+  const vec3 bh = vec3(0.0f);
+  const float bhr = 0.1f;
+  float bhmass = 5.0f * 0.001f; // premul G
 
+  // integration
   vec3 p = ro;
   vec3 pv = rd;
-  float dt = 0.02f;
-
+  const float dt = 0.02f;
   vec3 col = vec3(0.0f);
-
   float noncaptured = 1.0f;
 
   vec3 c1 = vec3(0.5f, 0.46f, 0.4f);
   vec3 c2 = vec3(1.0f, 0.8f, 0.6f);
 
-  for(float t = 0.0f; t < 1.0f; t += 0.005f) {
-    p += pv * dt * noncaptured;
+  // fixed iteration count, early-out when captured
+  const int MAX_STEPS = 175;         // original ~200 (1 / 0.005)
+  for(int i = 0; i < MAX_STEPS; ++i) {
+    if(noncaptured <= 0.0001f)
+      break;
 
-        // gravity
+    p += pv * (dt * noncaptured);
+
+    // gravity: compute bhv and reuse
     vec3 bhv = bh - p;
-    float r = dot(bhv, bhv);
-    pv += normalize(bhv) * ((bhmass) / r);
+    float r2 = dot(bhv, bhv) + 1e-6f; // prevent div0
+    float invLen = inversesqrt(r2);
+    // normalize(bhv) = bhv * invLen
+    // acceleration magnitude = bhmass / r2
+    // combine: accel = normalize(bhv) * (bhmass / r2)
+    pv += bhv * (invLen * (bhmass / r2));
 
-    noncaptured = smoothstep(0.0f, 0.666f, sdSphere(p - bh, bhr));
+    // capture factor (reuse distance)
+    float dist = sqrt(r2);
+    noncaptured = smoothstep(0.0f, 0.666f, dist - bhr);
 
-        // Texture for the accretion disc
+    // accretion disc texture
     float dr = length(bhv.xz);
-    float da = atan(bhv.x, bhv.z);
-    vec2 ra = vec2(dr, da * (0.01f + (dr - bhr) * 0.002f) + 2.0f * pi + iTime * 0.005f);
-    ra *= vec2(10.0f, 20.0f);
+    float da = atan(bhv.x, bhv.z); // keep same ordering as original
+    // compact texture coordinate generation:
+    float angleScale = 0.01f + (dr - bhr) * 0.002f;
+    vec2 ra = vec2(dr * 10.0f, (da * angleScale + 2.0f * PI + iTime * 0.005f) * 20.0f);
+    // sample lower frequency (reduce texture cost / cache pressure)
+    float tx = texture(iChannel1, ra * vec2(0.1f, 0.5f)).r;
+    float radial = max(0.0f, tx + 0.05f);
+    float falloff = 4.0f / (0.001f + (dr - bhr) * 50.0f);
 
-    vec3 dcol = mix(c2, c1, pow(length(bhv) - bhr, 2.0f)) * max(0.0f, texture(iChannel1, ra * vec2(0.1f, 0.5f)).r + 0.05f) * (4.0f / ((0.001f + (length(bhv) - bhr) * 50.0f)));
+    // color mix: avoid pow by squaring
+    float sq = (dr - bhr);
+    sq = sq * sq;
+    vec3 dcol = mix(c2, c1, sq) * radial * falloff;
 
-    col += max(vec3(0.0f), dcol * smoothstep(0.0f, 1.0f, -sdTorus((p * vec3(1.0f, 25.0f, 1.0f)) - bh, vec2(0.8f, 0.99f))) * noncaptured);
+    // torus SDF: scale p once
+    vec3 ps = p * vec3(1.0f, 25.0f, 1.0f) - bh;
+    float tor = sdTorus(ps, vec2(0.8f, 0.99f));
+    float torMask = smoothstep(0.0f, 1.0f, -tor);
 
-    col += vec3(1.0f, 0.9f, 0.85f) * (1.0f / vec3(dot(bhv, bhv))) * 0.0033f * noncaptured;
+    col += max(vec3(0.0f), dcol * torMask * noncaptured);
 
+    // simple brightening term (reuse r2)
+    col += vec3(1.0f, 0.9f, 0.85f) * (1.0f / r2) * 0.0033f * noncaptured;
   }
+
   fragColor = vec4(col, 1.0f);
 }
 
 void main() {
-    // gl_FragCoord.xy is pixel coordinates (1..width, 1..height)
   mainImage(FragColor, gl_FragCoord.xy);
 }