sparkjsdev · dmarcos · Nov 18, 2025 · Nov 17, 2025 · Nov 17, 2025
diff --git a/examples/interactive-deform/index.html b/examples/interactive-deform/index.html
@@ -0,0 +1,49 @@
+<!DOCTYPE html>
+<html>
+
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+  <title>Spark • Splat Experiment</title>
+  <style>
+    body {
+      margin: 0;
+      overflow: hidden;
+      font-family: Arial, sans-serif;
+      background: #000;
+    }
+    header {
+      position: absolute;
+      color: silver;
+      font-family: sans-serif;
+      padding: 12px 16px;
+      text-align: left;
+      width: 100vw;
+      pointer-events: none;
+      text-shadow: 
+        2px 2px 4px rgba(0, 0, 0, 0.8),
+        -1px -1px 2px rgba(0, 0, 0, 0.6),
+        1px -1px 2px rgba(0, 0, 0, 0.6),
+        -1px 1px 2px rgba(0, 0, 0, 0.6);
+      -webkit-text-stroke: 0.5px rgba(0, 0, 0, 0.7);
+    }
+  </style>
+</head>
+
+<body>
+  <header>Click and drag on the penguin to deform it • Release to see elastic bounce • A/D to rotate • W/S to zoom • Adjust parameters with GUI controls</header>
+  <script type="importmap">
+    {
+      "imports": {
+        "three": "/examples/js/vendor/three/build/three.module.js",
+        "three/addons/": "/examples/js/vendor/three/examples/jsm/",
+        "@sparkjsdev/spark": "/dist/spark.module.js",
+        "lil-gui": "/examples/js/vendor/lil-gui/dist/lil-gui.esm.js"
+      }
+    }
+  </script>
+  <script type="module" src="main.js"></script>
+</body>
+
+</html>
+
diff --git a/examples/interactive-deform/main.js b/examples/interactive-deform/main.js
@@ -0,0 +1,318 @@
+import { SparkRenderer, SplatMesh, dyno } from "@sparkjsdev/spark";
+import { GUI } from "lil-gui";
+import * as THREE from "three";
+import { getAssetFileURL } from "/examples/js/get-asset-url.js";
+
+const scene = new THREE.Scene();
+const camera = new THREE.PerspectiveCamera(
+  60,
+  window.innerWidth / window.innerHeight,
+  0.1,
+  1000,
+);
+const renderer = new THREE.WebGLRenderer({ antialias: false });
+renderer.setSize(window.innerWidth, window.innerHeight);
+document.body.appendChild(renderer.domElement);
+
+const spark = new SparkRenderer({ renderer });
+scene.add(spark);
+
+window.addEventListener("resize", onWindowResize, false);
+function onWindowResize() {
+  camera.aspect = window.innerWidth / window.innerHeight;
+  camera.updateProjectionMatrix();
+  renderer.setSize(window.innerWidth, window.innerHeight);
+}
+
+let rotationAngle = 0;
+let zoomDistance = 5.5;
+const minZoom = 1;
+const maxZoom = 20;
+const rotationSpeed = 0.02;
+const zoomSpeed = 0.1;
+
+camera.position.set(0, 3, zoomDistance);
+camera.lookAt(0, 1, 0);
+
+const keys = {};
+window.addEventListener("keydown", (event) => {
+  keys[event.key.toLowerCase()] = true;
+});
+window.addEventListener("keyup", (event) => {
+  keys[event.key.toLowerCase()] = false;
+});
+
+// Dyno uniforms for drag and bounce effects
+const dragPoint = dyno.dynoVec3(new THREE.Vector3(0, 0, 0));
+const dragDisplacement = dyno.dynoVec3(new THREE.Vector3(0, 0, 0));
+const dragRadius = dyno.dynoFloat(0.5);
+const dragActive = dyno.dynoFloat(0.0);
+const bounceTime = dyno.dynoFloat(0.0);
+const bounceBaseDisplacement = dyno.dynoVec3(new THREE.Vector3(0, 0, 0));
+const dragIntensity = dyno.dynoFloat(5.0);
+const bounceAmount = dyno.dynoFloat(0.5);
+const bounceSpeed = dyno.dynoFloat(0.5);
+let isBouncing = false;
+
+const gui = new GUI();
+const guiParams = {
+  intensity: dragIntensity.value,
+  radius: 0.5,
+  bounceAmount: 0.5,
+  bounceSpeed: 0.5,
+};
+gui
+  .add(guiParams, "intensity", 0, 10.0, 0.1)
+  .name("Deformation Strength")
+  .onChange((value) => {
+    dragIntensity.value = value;
+    if (splatMesh) {
+      splatMesh.updateVersion();
+    }
+  });
+gui
+  .add(guiParams, "radius", 0.25, 1.0, 0.1)
+  .name("Drag Radius")
+  .onChange((value) => {
+    dragRadius.value = value;
+    if (splatMesh) {
+      splatMesh.updateVersion();
+    }
+  });
+gui
+  .add(guiParams, "bounceAmount", 0, 1.0, 0.1)
+  .name("Bounce Strength")
+  .onChange((value) => {
+    bounceAmount.value = value;
+    if (splatMesh) {
+      splatMesh.updateVersion();
+    }
+  });
+gui
+  .add(guiParams, "bounceSpeed", 0, 1.0, 0.01)
+  .name("Bounce Speed")
+  .onChange((value) => {
+    bounceSpeed.value = value;
+    if (splatMesh) {
+      splatMesh.updateVersion();
+    }
+  });
+
+let isDragging = false;
+let dragStartPoint = null;
+let currentDragPoint = null;
+const raycaster = new THREE.Raycaster();
+raycaster.params.Points = { threshold: 0.5 };
+
+function createDragBounceDynoshader() {
+  return dyno.dynoBlock(
+    { gsplat: dyno.Gsplat },
+    { gsplat: dyno.Gsplat },
+    ({ gsplat }) => {
+      const shader = new dyno.Dyno({
+        inTypes: {
+          gsplat: dyno.Gsplat,
+          dragPoint: "vec3",
+          dragDisplacement: "vec3",
+          dragRadius: "float",
+          dragActive: "float",
+          bounceTime: "float",
+          bounceBaseDisplacement: "vec3",
+          dragIntensity: "float",
+          bounceAmount: "float",
+          bounceSpeed: "float",
+        },
+        outTypes: { gsplat: dyno.Gsplat },
+        statements: ({ inputs, outputs }) =>
+          dyno.unindentLines(`
+          ${outputs.gsplat} = ${inputs.gsplat};
+          vec3 originalPos = ${inputs.gsplat}.center;
+
+          // Calculate influence based on distance from drag point
+          float distToDrag = distance(originalPos, ${inputs.dragPoint});
+          float dragInfluence = 1.0 - smoothstep(0.0, ${inputs.dragRadius}*2., distToDrag);
+          float time = ${inputs.bounceTime};
+
+          // Apply drag deformation
+          if (${inputs.dragActive} > 0.5 && ${inputs.dragRadius} > 0.0) {
+            vec3 dragOffset = ${inputs.dragDisplacement} * dragInfluence * ${inputs.dragIntensity} * 50.0;
+            originalPos += dragOffset;
+          }
+
+          // Apply elastic bounce effect
+          float bounceFrequency = 1.0 + ${inputs.bounceSpeed} * 8.0;
+          vec3 bounceOffset = ${inputs.bounceBaseDisplacement} * dragInfluence * ${inputs.dragIntensity} * 50.0;
+          originalPos += bounceOffset * cos(time*bounceFrequency) * exp(-time*2.0*(1.0-${inputs.bounceAmount}*.9));
+
+          ${outputs.gsplat}.center = originalPos;
+        `),
+      });
+
+      return {
+        gsplat: shader.apply({
+          gsplat,
+          dragPoint: dragPoint,
+          dragDisplacement: dragDisplacement,
+          dragRadius: dragRadius,
+          dragActive: dragActive,
+          bounceTime: bounceTime,
+          bounceBaseDisplacement: bounceBaseDisplacement,
+          dragIntensity: dragIntensity,
+          bounceAmount: bounceAmount,
+          bounceSpeed: bounceSpeed,
+        }).gsplat,
+      };
+    },
+  );
+}
+
+let splatMesh = null;
+
+async function loadSplat() {
+  const splatURL = await getAssetFileURL("penguin.spz");
+  splatMesh = new SplatMesh({ url: splatURL });
+  splatMesh.quaternion.set(1, 0, 0, 0);
+  splatMesh.position.set(0, 0, 0);
+  scene.add(splatMesh);
+
+  await splatMesh.initialized;
+
+  splatMesh.worldModifier = createDragBounceDynoshader();
+  splatMesh.updateGenerator();
+}
+
+loadSplat().catch((error) => {
+  console.error("Error loading splat:", error);
+});
+
+// Convert mouse coordinates to normalized device coordinates
+function getMouseNDC(event) {
+  const rect = renderer.domElement.getBoundingClientRect();
+  return new THREE.Vector2(
+    ((event.clientX - rect.left) / rect.width) * 2 - 1,
+    -((event.clientY - rect.top) / rect.height) * 2 + 1,
+  );
+}
+
+// Raycast to find intersection point on splat
+function getHitPoint(ndc) {
+  if (!splatMesh) return null;
+  raycaster.setFromCamera(ndc, camera);
+  const hits = raycaster.intersectObject(splatMesh, false);
+  if (hits && hits.length > 0) {
+    return hits[0].point.clone();
+  }
+  return null;
+}
+
+let dragStartNDC = null;
+let dragScale = 1.0;
+
+renderer.domElement.addEventListener("pointerdown", (event) => {
+  if (!splatMesh) return;
+
+  const ndc = getMouseNDC(event);
+  const hitPoint = getHitPoint(ndc);
+
+  if (hitPoint) {
+    isDragging = true;
+    dragStartNDC = ndc.clone();
+    dragStartPoint = hitPoint.clone();
+    currentDragPoint = hitPoint.clone();
+
+    // Calculate scale factor for screen-to-world conversion
+    const distanceToCamera = camera.position.distanceTo(hitPoint);
+    const fov = camera.fov * (Math.PI / 180);
+    const screenHeight = 2.0 * Math.tan(fov / 2.0) * distanceToCamera;
+    dragScale = screenHeight / window.innerHeight;
+
+    dragPoint.value.copy(hitPoint);
+    dragActive.value = 1.0;
+    dragRadius.value = guiParams.radius;
+    dragDisplacement.value.set(0, 0, 0);
+
+    bounceTime.value = -1.0;
+    bounceBaseDisplacement.value.set(0, 0, 0);
+    isBouncing = false;
+  }
+});
+
+renderer.domElement.addEventListener("pointermove", (event) => {
+  if (!isDragging || !splatMesh || !dragStartPoint || !dragStartNDC) return;
+
+  const ndc = getMouseNDC(event);
+
+  // Convert screen space movement to world space
+  const mouseDelta = new THREE.Vector2(
+    (ndc.x - dragStartNDC.x) * dragScale,
+    (ndc.y - dragStartNDC.y) * dragScale,
+  );
+
+  const cameraRight = new THREE.Vector3();
+  const cameraUp = new THREE.Vector3();
+  camera.getWorldDirection(new THREE.Vector3());
+  cameraRight.setFromMatrixColumn(camera.matrixWorld, 0).normalize();
+  cameraUp.setFromMatrixColumn(camera.matrixWorld, 1).normalize();
+
+  const worldDisplacement = new THREE.Vector3()
+    .addScaledVector(cameraRight, mouseDelta.x)
+    .addScaledVector(cameraUp, mouseDelta.y);
+
+  currentDragPoint = dragStartPoint.clone().add(worldDisplacement);
+  dragDisplacement.value.copy(worldDisplacement);
+});
+
+renderer.domElement.addEventListener("pointerup", (event) => {
+  if (!isDragging) return;
+
+  isDragging = false;
+
+  // Start bounce animation with final displacement
+  if (currentDragPoint && dragStartPoint) {
+    const finalDisplacement = currentDragPoint.clone().sub(dragStartPoint);
+    bounceBaseDisplacement.value.copy(dragDisplacement.value);
+    bounceTime.value = 0.0;
+    isBouncing = true;
+  }
+
+  dragActive.value = 0.0;
+  dragDisplacement.value.set(0, 0, 0);
+  dragStartNDC = null;
+});
+
+renderer.setAnimationLoop(() => {
+  // Update bounce animation
+  if (isBouncing) {
+    bounceTime.value += 0.1;
+    if (splatMesh) {
+      splatMesh.updateVersion();
+    }
+  }
+
+  // Keyboard controls
+  if (keys.a) {
+    rotationAngle -= rotationSpeed;
+  }
+  if (keys.d) {
+    rotationAngle += rotationSpeed;
+  }
+
+  if (keys.w) {
+    zoomDistance = Math.max(minZoom, zoomDistance - zoomSpeed);
+  }
+  if (keys.s) {
+    zoomDistance = Math.min(maxZoom, zoomDistance + zoomSpeed);
+  }
+
+  // Update camera orbit
+  camera.position.x = Math.sin(rotationAngle) * zoomDistance;
+  camera.position.z = Math.cos(rotationAngle) * zoomDistance;
+  camera.position.y = 3;
+  camera.lookAt(0, 1.5, 0);
+
+  if (splatMesh) {
+    splatMesh.updateVersion();
+  }
+
+  renderer.render(scene, camera);
+});