From 2b4bb3085c0354671e2a6c0d5f0076e1f8c6c005 Mon Sep 17 00:00:00 2001
From: Muhammad Usama <lifeh2o@gmail.com>
Date: Thu, 20 Aug 2020 17:03:19 +0100
Subject: [PATCH] Added the missing 2d-vnoise.frag in chapter 11

---
 11/2d-vnoise.frag | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 11/2d-vnoise.frag

diff --git a/11/2d-vnoise.frag b/11/2d-vnoise.frag
new file mode 100644
index 0000000..4f4f4ec
--- /dev/null
+++ b/11/2d-vnoise.frag
@@ -0,0 +1,40 @@
+#ifdef GL_ES
+precision mediump float;
+#endif
+
+uniform vec2 u_resolution;
+uniform vec2 u_mouse;
+uniform float u_time;
+
+float random2(vec2 st){
+    st = vec2( dot(st,vec2(127.1,311.7)),
+              dot(st,vec2(269.5,183.3)) );
+    
+    return -1.0 + 2.0 * fract( sin( dot( st.xy, vec2(12.9898,78.233) ) ) * 43758.5453123);
+}
+
+// Gradient Noise by Inigo Quilez - iq/2013
+// https://www.shadertoy.com/view/lsf3WH
+float noise(vec2 st) {
+    vec2 i = floor(st);
+    vec2 f = fract(st);
+	
+	vec2 u = f*f*(3.0-2.0*f);
+
+    return mix( mix( random2( i + vec2(0.0,0.0) ), 
+                     random2( i + vec2(1.0,0.0) ), u.x),
+                mix( random2( i + vec2(0.0,1.0) ), 
+                     random2( i + vec2(1.0,1.0) ), u.x), u.y);
+}
+
+void main() {
+    vec2 st = gl_FragCoord.xy/u_resolution.xy;
+    st.x *= u_resolution.x/u_resolution.y;
+    vec3 color = vec3(0.0);
+
+    vec2 pos = vec2(st*10.0);
+
+    color = vec3( noise(pos)*.5+.5 );
+
+    gl_FragColor = vec4(color,1.0);
+}