diff --git a/examples/droste_effect_1/index.js b/examples/droste_effect_1/index.js
new file mode 100644
index 0000000..a592d7c
--- /dev/null
+++ b/examples/droste_effect_1/index.js
@@ -0,0 +1,41 @@
+import vert0 from './renderpass0/vert.js';
+import compute0 from './renderpass0/compute.js';
+import frag0 from './renderpass0/frag.js';
+
+import vert1 from './renderpass1/vert.js';
+import compute1 from './renderpass1/compute.js';
+import frag1 from './renderpass1/frag.js';
+
+import Points from 'points';
+import ShaderType from 'shadertype';
+import RenderPasses from 'renderpasses';
+import RenderPass from 'renderpass';
+
+
+/**
+ * Genuary 3: Droste Effect
+ * http://roy.red/posts/droste/
+ * https://github.com/ruby-processing/picrate-examples/blob/master/library/video/capture/data/droste.glsl
+ */
+
+const base = {
+
+    renderPasses: [
+        new RenderPass(vert0, frag0, compute0),
+        new RenderPass(vert1, frag1, compute1)
+    ],
+    /**
+     *
+     * @param {Points} points
+     */
+    init: async (points, folder) => {
+        points.setSampler('imageSampler', null, ShaderType.FRAGMENT);
+        points.setTexture2d('feedbackTexture', true);
+        points.setStorage('variables', 'Variables');
+        points.setStorage('colors', 'array<vec3f, 6>');
+    },
+    update: points => {
+    }
+}
+
+export default base;
\ No newline at end of file
diff --git a/examples/droste_effect_1/renderpass0/compute.js b/examples/droste_effect_1/renderpass0/compute.js
new file mode 100644
index 0000000..ff3883d
--- /dev/null
+++ b/examples/droste_effect_1/renderpass0/compute.js
@@ -0,0 +1,30 @@
+import { structs } from '../structs.js';
+
+const compute = /*wgsl*/`
+
+${structs}
+
+@compute @workgroup_size(8,8,1)
+fn main(
+    @builtin(global_invocation_id) GlobalId: vec3<u32>,
+    @builtin(workgroup_id) WorkGroupID: vec3<u32>,
+    @builtin(local_invocation_id) LocalInvocationID: vec3<u32>
+) {
+
+    if(variables.init == 0){
+        var index = 0;
+        colors[index] = vec3f(248, 208, 146) / 255; index++;
+        colors[index] = vec3f(21, 144, 151) / 255; index++;
+        colors[index] = vec3f(56, 164, 140) / 255; index++;
+        colors[index] = vec3f(26, 86, 120) / 255; index++;
+        colors[index] = vec3f(37, 36, 93) / 255; index++;
+        colors[index] = vec3f(87, 28, 86) / 255; index++;
+
+        variables.init = 1;
+    }
+
+
+}
+`;
+
+export default compute;
diff --git a/examples/droste_effect_1/renderpass0/frag.js b/examples/droste_effect_1/renderpass0/frag.js
new file mode 100644
index 0000000..37e7691
--- /dev/null
+++ b/examples/droste_effect_1/renderpass0/frag.js
@@ -0,0 +1,127 @@
+import { fnusin } from 'animation';
+import { structs } from '../structs.js';
+const frag = /*wgsl*/`
+
+${fnusin}
+${structs}
+
+fn opSmoothSubtraction(d1: f32, d2: f32, k: f32) -> f32{
+    let h = clamp(.5 - .5 * (d2 + d1) / k, 0., 1.);
+    return mix(d2, -d1, h) + k * h * (1. - h);
+}
+
+fn smin(d1: f32, d2: f32, k: f32) -> f32{
+    let h = max(k-abs(d1-d2), 0.)/k;
+    return min(d1, d2) - h*h*h*k*(1./6.);
+}
+
+fn sdBox(p:vec3f, b: vec3f) -> f32 {
+    let q = abs(p) - b;
+    return length(max(q, vec3f(0.) )) + min(max(q.x, max(q.y, q.z)), 0.);
+}
+
+fn rot2d(angle: f32) -> mat2x2<f32> {
+    let s = sin(angle);
+    let c = cos(angle);
+    return mat2x2(c, -s, s, c);
+}
+
+fn paletteLerp(a:array<vec3f,6>, value:f32) -> vec3f {
+    let numElements = 6.;
+    let elementPercent = 1 / numElements;
+    let index = value / elementPercent;
+    let minIndex = i32(floor(index));
+    let maxIndex = i32(ceil(index));
+
+    let a0 = a[minIndex];
+    let a1 = a[maxIndex];
+
+    return mix(a0, a1, fract(index));
+}
+
+fn map(p: vec3f, step:f32) -> f32 {
+    // input copy to rotate
+    var q = p;
+    var qRotated = q.xy * rot2d(params.time * .53);
+    q = vec3(qRotated, q.z);
+
+    qRotated = q.xz * rot2d(params.time * .633);
+    q = vec3(qRotated, q.y);
+
+    // scale down by 4 with  p*4 and correcting distotrion dividing by 4
+    let scale = .5;
+
+    // for repetition
+    let boxBase = sdBox(q * scale, vec3(.5)) / scale; // cube sdf
+    let boxHollow1 = sdBox(q * scale, vec3(.4,.4, 1.)) / scale; // cube sdf
+    let boxHollow2 = sdBox(q * scale, vec3(1.,.4, .4)) / scale; // cube sdf
+    let boxHollow3 = sdBox(q * scale, vec3(.4,1., .4)) / scale; // cube sdf
+
+    var box = opSmoothSubtraction(boxHollow1, boxBase, .1);
+    box = opSmoothSubtraction(boxHollow2, box, .1);
+    box = opSmoothSubtraction(boxHollow3, box, .1);
+
+    let ground = p.y + .75;
+
+    // closest distance to the scene
+    return smin(ground, box, 1.);
+}
+
+@fragment
+fn main(
+    @location(0) color: vec4<f32>,
+    @location(1) uv: vec2<f32>,
+    @location(2) ratio: vec2<f32>,  // relation between params.screen.x and params.screen.y
+    @location(3) uvr: vec2<f32>,    // uv with aspect ratio corrected
+    @location(4) mouse: vec2<f32>,
+    @builtin(position) position: vec4<f32>
+) -> @location(0) vec4<f32> {
+    let sliderA = 1.;
+    let sliderB = .1116;
+    let uv2 = uvr * 4 - (vec2(2) * ratio); // clip space
+    // let m = mouse * 4 - (vec2(2) * ratio);
+    let m = vec2f(.5, .5) * 4 - (vec2(2) * ratio);
+
+    // initialization
+    var ro = vec3f(0, 0, -3); // ray origin
+    var rd = normalize(vec3(uv2 * sliderB * 5, 1)); // ray direction one ray per uv position
+
+    var t = 0.; // total distance traveled // travel distance
+
+    var col = vec3f();
+
+    // Vertical camera rotation
+    let mouseRotY = rot2d(-m.y);
+    // ro.xz *= rot2d(-m.x);
+    ro = vec3(ro.x, ro.yz * mouseRotY);
+    // rd.xz *= rot2d(-m.x);
+    rd = vec3(rd.x, rd.yz * mouseRotY);
+
+    // Horizontal camera rotation
+    let mouseRotX = rot2d(-m.x);
+    // ro.xz *= rot2d(-m.x);
+    ro = vec3(ro.xz * mouseRotX, ro.y).xzy;
+    // rd.xz *= rot2d(-m.x);
+    rd = vec3(rd.xz * mouseRotX, rd.y).xzy;
+
+    // Raymarching
+    var i = 0;
+    for (; i < 80; i++) {
+        let p = ro + rd * t; // position along the ray
+        let d = map(p, f32(i)); // current distance to the scene
+        t += d; // "march" the ray
+
+        // early stop if close enough, test this .001 value with others to test
+        // early stop if too far
+        if(d < .001 || d > 100.){
+            break;
+        }
+    }
+    let value = (t * sliderA * f32(i) * .005);
+    col = paletteLerp(colors, value);
+
+    return vec4(col, 1);
+}
+`;
+
+export default frag;
diff --git a/examples/droste_effect_1/renderpass0/vert.js b/examples/droste_effect_1/renderpass0/vert.js
new file mode 100644
index 0000000..3a7e5c9
--- /dev/null
+++ b/examples/droste_effect_1/renderpass0/vert.js
@@ -0,0 +1,17 @@
+import { structs } from '../structs.js';
+
+const vert = /*wgsl*/`
+${structs}
+@vertex
+fn main(
+    @location(0) position: vec4<f32>,
+    @location(1) color: vec4<f32>,
+    @location(2) uv: vec2<f32>,
+    @builtin(vertex_index) vertexIndex: u32
+) -> Fragment {
+
+    return defaultVertexBody(position, color, uv);
+}
+`;
+
+export default vert;
diff --git a/examples/droste_effect_1/renderpass1/compute.js b/examples/droste_effect_1/renderpass1/compute.js
new file mode 100644
index 0000000..7e21271
--- /dev/null
+++ b/examples/droste_effect_1/renderpass1/compute.js
@@ -0,0 +1,15 @@
+import { structs } from '../structs.js';
+
+const compute = /*wgsl*/`
+${structs}
+@compute @workgroup_size(8,8,1)
+fn main(
+    @builtin(global_invocation_id) GlobalId: vec3<u32>,
+    @builtin(workgroup_id) WorkGroupID: vec3<u32>,
+    @builtin(local_invocation_id) LocalInvocationID: vec3<u32>
+) {
+    // let time = params.time;
+}
+`;
+
+export default compute;
diff --git a/examples/droste_effect_1/renderpass1/frag.js b/examples/droste_effect_1/renderpass1/frag.js
new file mode 100644
index 0000000..8c2191a
--- /dev/null
+++ b/examples/droste_effect_1/renderpass1/frag.js
@@ -0,0 +1,106 @@
+import { sdfLine2, sdfSegment } from 'sdf';
+import { fnusin } from 'animation';
+import { snoise } from 'noise2d';
+import { PI, E, rotateVector } from 'math';
+import { texturePosition } from 'image';
+import { RGBAFromHSV, layer } from 'color';
+import { structs } from '../structs.js';
+const frag = /*wgsl*/`
+
+${structs}
+${fnusin}
+${snoise}
+${sdfSegment}
+${sdfLine2}
+${PI}
+${E}
+${texturePosition}
+${rotateVector}
+${layer}
+${RGBAFromHSV}
+
+const RADIAN = 0.0174533;
+
+fn sdfRing(position:vec2f, radius1:f32, uv:vec2f) -> f32 {
+    let d = distance(uv, position);
+    let st0 = 1. - smoothstep(radius1, radius1, d);
+    let st1 = smoothstep(radius1 - .004, radius1 - .004, d);
+    return st0 * st1;
+}
+
+fn annulus(position:vec2f, radius1:f32, radius2:f32, uv:vec2f) -> f32 {
+    let ring1 = sdfRing(position, radius1, uv);
+    let ring0 = sdfRing(position, radius2, uv);
+    const w = .004;
+    var vertical = sdfLine2(position + vec2(0, radius1), position + vec2(0, radius2), w, uv);
+    vertical += sdfLine2(position + vec2(0, -radius1), position + vec2(0, -radius2), w, uv);
+    var horizontal = sdfLine2(position + vec2(radius1, 0), position + vec2(radius2, 0), w, uv);
+    horizontal += sdfLine2(position + vec2(-radius1, 0), position + vec2(-radius2, 0), w, uv);
+    return ring0 + ring1 + vertical + horizontal;
+}
+
+fn complexExp(z: vec2f) -> vec2f {
+    return vec2(exp(z.x)*cos(z.y),exp(z.x)*sin(z.y));
+}
+
+fn complexLog(z: vec2f) -> vec2f {
+    return vec2(log(length(z)), atan2(z.y, z.x));
+}
+fn complexMult(a:vec2f, b:vec2f) -> vec2f {
+    return vec2(a.x*b.x - a.y*b.y, a.x*b.y + a.y*b.x);
+}
+
+fn complexMag(z:vec2f) -> f32 {
+    return pow(length(z), 2.0);
+}
+fn complexReciprocal(z:vec2f) -> vec2f {
+    return vec2(z.x / complexMag(z), -z.y / complexMag(z));
+}
+
+fn complexDiv(a:vec2f, b:vec2f) -> vec2f {
+    return complexMult(a, complexReciprocal(b));
+}
+
+@fragment
+fn main(
+    @location(0) color: vec4<f32>,
+    @location(1) uv: vec2<f32>,
+    @location(2) ratio: vec2<f32>,  // relation between params.screen.x and params.screen.y
+    @location(3) uvr: vec2<f32>,    // uv with aspect ratio corrected
+    @location(4) mouse: vec2<f32>,
+    @builtin(position) position: vec4<f32>
+) -> @location(0) vec4<f32> {
+
+    let sliderA = .192;
+    let sliderB = 1 + 40 * fnusin(1);
+    let r1 = 0.3;
+    let r2 = 0.7;
+    let pos = vec2f(0);
+    var z = (uvr * 2) - (vec2(1) * ratio);
+    z = z * sliderB * 10;
+
+    // 4. Take the tiled strips back to ordinary space.
+    z = complexLog(z);
+    // 3. Scale and rotate the strips
+    let scale = log(r2/r1);
+    // Negate the angle to twist the other way
+    let angle = atan(scale/(2.0*PI));
+    z = complexDiv(z, complexExp(vec2(0,angle))*cos(angle));
+
+    // 2. Tile the strips
+    z.x = z.x % log(r2/r1);
+    // 1. Take the annulus to a strip
+    z = complexExp(z) * r1;
+
+    let c = RGBAFromHSV( atan2(z.y,z.x)/PI*2,1.,1.);
+    let imageColor = texturePosition(feedbackTexture, imageSampler, vec2(-.5) * ratio, z / sliderA / 10 , false);
+
+    var a = annulus(pos, r1, r2, z);
+
+    let board = sin(z*20.0)*10.;
+
+    return imageColor;
+}
+`;
+
+export default frag;
diff --git a/examples/droste_effect_1/renderpass1/vert.js b/examples/droste_effect_1/renderpass1/vert.js
new file mode 100644
index 0000000..3a7e5c9
--- /dev/null
+++ b/examples/droste_effect_1/renderpass1/vert.js
@@ -0,0 +1,17 @@
+import { structs } from '../structs.js';
+
+const vert = /*wgsl*/`
+${structs}
+@vertex
+fn main(
+    @location(0) position: vec4<f32>,
+    @location(1) color: vec4<f32>,
+    @location(2) uv: vec2<f32>,
+    @builtin(vertex_index) vertexIndex: u32
+) -> Fragment {
+
+    return defaultVertexBody(position, color, uv);
+}
+`;
+
+export default vert;
diff --git a/examples/droste_effect_1/structs.js b/examples/droste_effect_1/structs.js
new file mode 100644
index 0000000..d4bf461
--- /dev/null
+++ b/examples/droste_effect_1/structs.js
@@ -0,0 +1,7 @@
+export const structs = /*wgsl*/`
+
+struct Variables {
+    init: i32,
+}
+
+`;
diff --git a/examples/index_files/shader_projects.js b/examples/index_files/shader_projects.js
index 12b73ae..7ff718a 100644
--- a/examples/index_files/shader_projects.js
+++ b/examples/index_files/shader_projects.js
@@ -12,6 +12,7 @@ export const shaderProjects = [
     { name: 'Dithering 3 - 2', path: './dithering3_2/index.js', uri: 'dithering3_2', desc: 'Better dithering that affects the entire image at once.', author: 'absulit', authlink: 'http://absulit.com', fitWindow: false, enabled: true, tax: 'showcase' },
     { name: 'Dithering 4', path: './dithering4/index.js', uri: 'dithering4', desc: '', author: 'absulit', authlink: 'http://absulit.com', fitWindow: true, enabled: true, tax: 'showcase' },
     { name: 'Dithering Video 1', path: './dithering_video_1/index.js', uri: 'dithering_video_1', desc: '', author: 'absulit', authlink: 'http://absulit.com', fitWindow: false, enabled: true, tax: 'showcase' },
+    { name: 'Droste Effect 1', path: './droste_effect_1/index.js', uri: 'droste_effect_1', desc: 'Raymarched scene with Droste Effect.<br>Based on <a rel="noopener" target="_blank"  href="http://roy.red/posts/droste/">http://roy.red/posts/droste/</a>', author: 'absulit', authlink: 'http://absulit.com', fitWindow: true, enabled: true, tax: 'showcase, raymarching' },
     { name: 'Events 1', path: './events1/index.js', uri: 'events1', desc: 'WGSL fires an event and is read on the JavaScript side. Visible in console.', author: 'absulit', authlink: 'http://absulit.com', fitWindow: true, enabled: true, tax: 'reference' },
     { name: 'Image Scale 1', path: './imagescale1/index.js', uri: 'imagescale1', desc: 'Layering of images', author: 'absulit', authlink: 'http://absulit.com', fitWindow: true, enabled: true, tax: 'reference' },
     { name: 'Image Texture 1', path: './imagetexture1/index.js', uri: 'imagetexture1', desc: 'How to load a texture.', author: 'absulit', authlink: 'http://absulit.com', fitWindow: true, enabled: true, tax: 'reference' },
diff --git a/examples/main.js b/examples/main.js
index 87a5af7..4a64a4a 100644
--- a/examples/main.js
+++ b/examples/main.js
@@ -110,6 +110,10 @@ const authorLinkEl = infoEl.querySelector('#author-link');
 
 async function loadShaderByIndex(index) {
     console.clear();
+    if (index > shaderProjects.length) {
+        index = 0;
+    }
+
     localStorage.setItem('selected-shader', index);
     const shaderProject = shaderProjects[index];
     sourceBtn.href = `https://github.com/Absulit/points/tree/master/examples/${shaderProject.uri}`;
@@ -137,7 +141,7 @@ async function loadShaderByURI() {
     }
 
     lastSelected = Array.from(document.querySelectorAll('#nav a')).filter(a => a.index == index)[0];
-    lastSelected.classList.add('selected');
+    lastSelected?.classList.add('selected');
 }
 
 //---
diff --git a/examples/style.css b/examples/style.css
index 2602168..3cd7cfd 100644
--- a/examples/style.css
+++ b/examples/style.css
@@ -130,4 +130,8 @@ h2 {
 
 #nowebgpu.show {
     display: flex;
-}
\ No newline at end of file
+}
+
+div.dg.ac {
+    z-index: 2;
+}