diff --git a/shaders/mat_rain_windscreen.frag b/shaders/mat_rain_windscreen.frag
index f7f057ca..99d7dadf 100644
--- a/shaders/mat_rain_windscreen.frag
+++ b/shaders/mat_rain_windscreen.frag
@@ -25,6 +25,7 @@ layout(location = 1) out vec4 out_motion;
 #include <light_common.glsl>
 #include <apply_fog.glsl>
 #include <tonemapping.glsl>
+#include <random.glsl>
 
 uniform sampler2D diffuse;
 uniform sampler2D raindropsatlas;
@@ -34,10 +35,6 @@ uniform float specular_intensity = 1.0;
 uniform float wobble_strength    = 0.002;
 uniform float wobble_speed       = 30.0;
 
-float hash(vec2 p) {
-    return fract(sin(dot(p, vec2(12.9898, 78.233))) * 43758.5453);
-}
-
 vec4 getDropTex(float choice, vec2 uv) {
     vec2 offset;
     if      (choice < 0.25) offset = vec2(0.0, 0.0);
@@ -54,13 +51,14 @@ void main() {
     if (tex_color.a < 0.01) discard;
 
     vec2 rainCoord = f_coord;
+    float gridSize = ceil(param[2].x);
 
     const float numDrops      = 20000.0;
     const float cycleDuration = 4.0;
-    const float squareMin     = 0.0035;
-    const float squareMax     = 0.008;
+    
+    float squareMin     = 0.5 / gridSize;
+    float squareMax     = 1.2 / gridSize;
 
-    float gridSize = ceil(param[2].x);
     vec2  cell     = floor(rainCoord * gridSize);
 
     vec3 dropLayer = vec3(0.0);
@@ -76,37 +74,37 @@ void main() {
             float side;
             float mixFactor = GetMixFactor(neighborCenter, side);
             
-            if(mixFactor < hash(neighborCell + vec2(mix(0., .2137, side), 0.))) {
+            uint seed = Hash(uvec3(neighborCell, side));
+            
+            if(mixFactor < RandF(seed)) {
               continue;
             }
-            
-            float i = neighborCell.x + neighborCell.y * gridSize;
 
             // Show a percentage of droplets given by rain intensity param
-            float activationSeed = hash(vec2(i, 0.333 + side));
+            float activationSeed = RandF(seed);
             if (activationSeed > rain_params.x)
                 continue; // kropla nieaktywna
 
             // Randomly modulate droplet center & size
-            vec2 dropCenter = (neighborCell + vec2(hash(vec2(i, 0.12 + side)), hash(vec2(i, 0.34 + side)))) / gridSize;
-            float squareSize = mix(squareMin, squareMax, hash(vec2(i, 0.56 + side)));
+            vec2 dropCenter = (neighborCell + vec2(RandF(seed), RandF(seed))) / gridSize;
+            float squareSize = mix(squareMin, squareMax, RandF(seed));
 
-            float lifeTime = time + hash(vec2(i, 0.78 + side)) * cycleDuration;
+            float lifeTime = time + RandF(seed) * cycleDuration;
             float phase    = fract(lifeTime / cycleDuration);
             float active   = clamp(1.0 - phase, 0.0, 1.0);
 
             // Gravity influence (TODO add vehicle speed & wind here!)
             float gravityStart = 0.5;
             float gravityPhase = smoothstep(gravityStart, 1.0, phase);
-            float dropMass     = mix(0.3, 1.2, hash(vec2(i, 0.21 + side)));
+            float dropMass     = mix(0.3, 1.2, RandF(seed));
             float gravitySpeed = 0.15 * dropMass;
             vec2  gravityOffset = vec2(0.0, gravityPhase * gravitySpeed * phase);
 
             // Random wobble
-            bool hasWobble = (hash(vec2(i, 0.91 + side)) < 0.10);
+            bool hasWobble = (RandF(seed) < 0.10);
             vec2 wobbleOffset = vec2(0.0);
             if (hasWobble && gravityPhase > 0.0) {
-                float intensity = sin(time * wobble_speed + i) * wobble_strength * gravityPhase;
+                float intensity = sin(time * wobble_speed + RandF(seed) * 100.) * wobble_strength * gravityPhase;
                 wobbleOffset = vec2(intensity, 0.0);
             }
 
@@ -125,7 +123,7 @@ void main() {
 
             if (mask > 0.001) {
                 vec2 localUV = (diff + squareSize * 0.5) / squareSize;
-                float choice = hash(vec2(i, 0.99 + side));
+                float choice = RandF(seed);
                 vec4 dropTex = getDropTex(choice, localUV);
                 float sharpAlpha = smoothstep(0.3, 0.9, dropTex.a);
 
@@ -139,7 +137,7 @@ void main() {
 
                 float sparkle = 0.0;
                 if (hasWobble) {
-                    sparkle = pow(abs(sin(f_coord.x * 8.0 + time * 2.0 + hash(vec2(i, 0.9 + side)) * 6.2831)), 40.0)
+                    sparkle = pow(abs(sin(f_coord.x * 8.0 + time * 2.0 + RandF(seed) * 6.2831)), 40.0)
                               * mix(0.2, 1.0, sunFactor);
                 }
 
diff --git a/shaders/random.glsl b/shaders/random.glsl
new file mode 100644
index 00000000..0b25c987
--- /dev/null
+++ b/shaders/random.glsl
@@ -0,0 +1,39 @@
+
+uint Hash(uint s);
+uint Hash(uvec2 s);
+uint Hash(uvec3 s);
+uint Hash(float s);
+uint HashCombine(uint seed, uint value);
+
+// Evolving Sub-Grid Turbulence for Smoke Animation
+// H. Schechter and R. Bridson
+uint Hash(uint s) {
+  s ^= 2747636419u;
+  s *= 2654435769u;
+  s ^= s >> 16u;
+  s *= 2654435769u;
+  s ^= s >> 16u;
+  s *= 2654435769u;
+  return s;
+}
+
+uint Hash(uvec2 s) {
+  return HashCombine(Hash(s.x), s.y);
+}
+
+uint Hash(uvec3 s) {
+  return HashCombine(Hash(s.xy), s.z);
+}
+
+uint HashCombine(uint seed, uint value) {
+  return seed ^ (Hash(value) + 0x9e3779b9u + (seed<<6u) + (seed>>2u));
+}
+
+uint Rand(inout uint seed) {
+  seed = Hash(seed);
+  return seed;
+}
+
+float RandF(inout uint seed) {
+  return float(Rand(seed)) * 2.3283064365386963e-10;
+}