added simple pom

Simple-Parallax-Occlusion-Mapping/Image.glsl

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+
+mat2 mkrot(in float t)
+{
+    float s = sin(t);
+    float c = cos(t);
+    return mat2(c,-s,s,c);
+}
+
+void rotCam(inout vec3 ro, inout vec3 rd)
+{
+    mat2 a = mkrot(.4);
+    
+    ro.yz *= a;
+    rd.yz *= a;
+
+    mat2 b = mkrot(iTime*.4);
+    
+    ro.xz *= b;
+    rd.xz *= b;
+ 
+    mat2 c = mkrot(sin(iTime*.4) * .5);
+    
+    ro.xy *= c;
+    rd.xy *= c;
+}
+
+vec2 pom(in vec2 uv, in vec3 i)
+{
+    float y = 0.0;
+
+    float d = 2./256.;
+    for (int k = 0; k < 512; k++)
+    {
+        float h = textureLod(iChannel0, uv, 2.5).r;
+        if (abs(h - y) > 1.)
+            break;
+    
+        y += i.y * d;
+        uv += i.xz * d * 1e-1;
+    }
+
+    return uv;
+}
+
+vec3 pomNor(in vec2 uv)
+{
+    const vec2 eps = vec2(1e-2,0);
+    float t = textureLod(iChannel0, uv + eps.xy, 2.5).r;
+    float b = textureLod(iChannel0, uv - eps.xy, 2.5).r;
+    float l = textureLod(iChannel0, uv - eps.yx, 2.5).r;
+    float r = textureLod(iChannel0, uv + eps.yx, 2.5).r;
+    
+    return normalize(vec3(r-l, 1e-1, b-t));
+}
+
+void mainImage( out vec4 fragColor, in vec2 fragCoord )
+{
+    vec2 uv = (fragCoord-.5*iResolution.xy)/iResolution.y;
+
+    vec3 s = normalize(vec3(1,1,0));
+
+    vec3 ro = vec3(0,-.1,-1);
+    vec3 rd = normalize(vec3(uv, 1));
+    rotCam(ro, rd);
+    vec3 col = vec3(0);
+    
+    float t = -ro.y/rd.y;
+    vec3 p = ro + rd * t;
+    
+    vec3 ap = abs(p);
+    if (t > 0. && max(max(ap.x,ap.y),ap.z) < .5)
+    {
+        vec2 st = pom(p.xz, rd);
+        vec3 n = pomNor(st);
+        col = texture(iChannel0, st).rgb * dot(n, s);
+    }
+
+    fragColor = vec4(col,1.0);
+}

Simple-Parallax-Occlusion-Mapping/README.md

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+# Simple Parallax Occlusion Mapping
+![POM](https://git.teridax.de/teridax/Shadertoy-Shaders/raw/branch/main/Simple-Parallax-Occlusion-Mapping/overview.png)
+
+Parallax Occlusion Mapping is a way of adding 3D bumps to a flat surface, based on a heightmap. This does not actually displace the geometry
+but performs a ray casting algorithm on the surface which acts a "portal" to a more detailed surface.
+This Implememtation is a basic first draft and assumes the surface normal to a constant up vector.