From c1a335e8ee26d300a8d8f5d98af5058a1c4ca733 Mon Sep 17 00:00:00 2001
From: kali <64813012+kali-shade@users.noreply.github.com>
Date: Tue, 22 Jul 2025 15:08:50 -0300
Subject: [PATCH] Added particle flow transition to examples (#131)

* Added particle flow transition to examples

* Added particle flow transition to examples
---
 examples/splat-flow/index.html | 259 +++++++++++++++++++++++++++++++++
 1 file changed, 259 insertions(+)
 create mode 100644 examples/splat-flow/index.html

diff --git a/examples/splat-flow/index.html b/examples/splat-flow/index.html
new file mode 100644
index 0000000..4e237ff
--- /dev/null
+++ b/examples/splat-flow/index.html
@@ -0,0 +1,259 @@
+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
+    <title>Spark • Splat Flow</title>
+    <style>
+      html, body { margin: 0; height: 100%; width: 100%; background-color: black; }
+      #canvas { position: absolute; top: 0; left: 0; width: 100%; height: 100%; outline: none; touch-action: none; }
+    </style>
+  </head>
+  <body>
+    <canvas id="canvas" tabindex="0"></canvas>
+    <script type="importmap">
+      {
+        "imports": {
+          "three": "/examples/js/vendor/three/build/three.module.js",
+          "lil-gui": "/examples/js/vendor/lil-gui/dist/lil-gui.esm.js",
+          "@sparkjsdev/spark": "/dist/spark.module.js"
+        }
+      }
+    </script>
+    <script type="module">
+      import { dyno, SparkRenderer, SplatMesh } from "@sparkjsdev/spark";
+      import * as THREE from "three";
+      import { GLTFLoader } from "three/examples/jsm/loaders/GLTFLoader.js";
+      import { getAssetFileURL } from "/examples/js/get-asset-url.js";
+      import { GUI } from "lil-gui";
+
+      const splatFiles = ["woobles.spz", "dessert.spz", "robot-head.spz"];
+      const skyFile = "dali-env.glb";
+      const PARAMETERS = { speedMultiplier: 1.0, objectRotation: true, pause: false, fixedMinScale: false, waves: 0.5, cameraRotation: true };
+      const PAUSE_SECONDS = 2.0;
+
+      function getTransitionState(t, fadeInTime, fadeOutTime, period) {
+        const one = dyno.dynoFloat(1.0);
+        const pauseTime = dyno.dynoFloat(PAUSE_SECONDS);
+        const cycleTime = dyno.add(one, pauseTime);
+        const total = dyno.mul(period, cycleTime);
+        const wrapT = dyno.mod(t, total);
+        const pos = dyno.mod(wrapT, cycleTime);
+        const inPause = dyno.greaterThan(pos, one);
+        const normT = dyno.select(inPause, one, pos);
+        const fadeIn = dyno.and(
+          dyno.greaterThan(wrapT, dyno.mul(fadeInTime, cycleTime)),
+          dyno.lessThan(wrapT, dyno.mul(dyno.add(fadeInTime, one), cycleTime))
+        );
+        const fadeOut = dyno.and(
+          dyno.greaterThan(wrapT, dyno.mul(fadeOutTime, cycleTime)),
+          dyno.lessThan(wrapT, dyno.mul(dyno.add(fadeOutTime, one), cycleTime))
+        );
+        return { inTransition: dyno.or(fadeIn, fadeOut), isFadeIn: fadeIn, normT };
+      }
+
+      function contractionDyno(centerGLSL) {
+        return new dyno.Dyno({
+          inTypes: { gsplat: dyno.Gsplat, inTransition: "bool", fadeIn: "bool", t: "float", gt: "float", objectIndex: "int", fixedMinScale: "bool", waves: "float" },
+          outTypes: { gsplat: dyno.Gsplat },
+          globals: () => [ dyno.unindent(`
+            float hash13(vec3 p3) { p3 = fract(p3 * .1031); p3 += dot(p3, p3.yzx + 33.33); return fract((p3.x + p3.y) * p3.z); }
+            float hash11(float p) { p = fract(p * .1031); p += dot(p, p + 33.33); return fract(p * p); }
+            float fadeInOut(float t) { return abs(mix(-1., 1., t)); }
+            ${centerGLSL}
+            float applyBrightness(float t) { return .5 + fadeInOut(t) * .5; }
+            vec3 applyCenter(vec3 center, float t, float id, int idx, float waves) {
+              int next = (idx + 1) % 3;
+              vec3 cNext = getCenterOfMass(next);
+              vec3 cOwn = getCenterOfMass(idx);
+              float f = fadeInOut(t);
+              float v = .5 + hash11(id) * 2.;
+              vec3 p = t < .5 ? mix(cNext, center, pow(f, v)) : mix(cOwn, center, pow(f, v));
+              return p + length(sin(p*2.5)) * waves * (1.-f)*smoothstep(0.5,0.,t) * 2.;
+            }
+            vec3 applyScale(vec3 s, float t, bool fixedMin) { return mix(fixedMin ? vec3(.02) : s * .2, s, pow(fadeInOut(t), 3.)); }
+            float applyOpacity(float t, float gt, int idx) {
+              float p = float(${PAUSE_SECONDS});
+              float c = 1.0 + p;
+              float tot = 3.0 * c;
+              float w = mod(gt + p + .5, tot);
+              int cur = int(floor(w / c));
+              return cur == idx ? .1+fadeInOut(t) : 0.0;
+            }
+          `) ],
+          statements: ({ inputs, outputs }) => dyno.unindentLines(`
+            ${outputs.gsplat} = ${inputs.gsplat};
+            ${outputs.gsplat}.center = applyCenter(${inputs.gsplat}.center, ${inputs.t}, float(${inputs.gsplat}.index), ${inputs.objectIndex}, ${inputs.waves});
+            ${outputs.gsplat}.scales = applyScale(${inputs.gsplat}.scales, ${inputs.t}, ${inputs.fixedMinScale});
+            ${outputs.gsplat}.rgba.a *= applyOpacity(${inputs.t}, ${inputs.gt}, ${inputs.objectIndex});
+            ${outputs.gsplat}.rgba.rgb *= applyBrightness(${inputs.t});
+          `)
+        });
+      }
+
+      function getTransitionModifier(inTrans, fadeIn, t, idx, gt, centerGLSL, fixedMinScale, waves) {
+        const dyn = contractionDyno(centerGLSL);
+        return dyno.dynoBlock(
+          { gsplat: dyno.Gsplat },
+          { gsplat: dyno.Gsplat },
+          ({ gsplat }) => ({ gsplat: dyn.apply({ gsplat, inTransition: inTrans, fadeIn, t, gt, objectIndex: idx, fixedMinScale, waves }).gsplat })
+        );
+      }
+
+      async function loadGLB(file, isEnv = false) {
+        const url = await getAssetFileURL(file);
+        const loader = new GLTFLoader();
+        const gltf = await new Promise((res, rej) => loader.load(url, res, undefined, rej));
+        gltf.scene.traverse(child => {
+          if (child.isMesh && child.material) {
+            const mat = new THREE.MeshBasicMaterial({ color: child.material.color, map: child.material.map });
+            if (isEnv) {
+              mat.side = THREE.BackSide;
+              mat.map.mapping = THREE.EquirectangularReflectionMapping;
+              mat.map.colorSpace = THREE.LinearSRGBColorSpace;
+              mat.map.needsUpdate = true;
+            }
+            child.material = mat;
+          }
+        });
+        return gltf.scene;
+      }
+
+      const canvas = document.getElementById("canvas");
+      const renderer = new THREE.WebGLRenderer({ canvas, antialias: false });
+      renderer.setPixelRatio(window.devicePixelRatio);
+      renderer.setSize(canvas.clientWidth, canvas.clientHeight, false);
+      renderer.setClearColor(0x000000, 1);
+
+      const scene = new THREE.Scene();
+      const spark = new SparkRenderer({ renderer });
+      scene.add(spark);
+
+      const camera = new THREE.PerspectiveCamera(50, innerWidth / innerHeight, 0.01, 1000);
+      camera.position.set(0, 5, 8);
+      camera.lookAt(0, 0, 0);
+      scene.add(camera);
+
+      window.addEventListener("resize", () => {
+        const w = canvas.clientWidth;
+        const h = canvas.clientHeight;
+        renderer.setSize(w, h, false);
+        camera.aspect = w / h;
+        camera.updateProjectionMatrix();
+      });
+
+      const time = dyno.dynoFloat(0.0);
+
+      async function loadAssets() {
+        const env = await loadGLB(skyFile, true);
+        scene.add(env);
+
+        const meshes = [];
+        const period = dyno.dynoFloat(splatFiles.length);
+        const positions = [
+          new THREE.Vector3(-5, -2.2, -3),
+          new THREE.Vector3(5, -2.5, 0),
+          new THREE.Vector3(0, 1.5, 2)
+        ];
+
+        for (let i = 0; i < splatFiles.length; i++) {
+          const url = await getAssetFileURL(splatFiles[i]);
+          const m = new SplatMesh({ url });
+          await m.initialized;
+          m.position.copy(positions[i]);
+          m.rotateX(Math.PI);
+          scene.add(m);
+          meshes.push(m);
+        }
+
+        const centers = meshes.map(m => {
+          const box = new THREE.Box3();
+          m.packedSplats.forEachSplat((_, c) => {
+            box.expandByPoint(c);
+          });
+          const localCenter = box.getCenter(new THREE.Vector3());
+          localCenter.y = -localCenter.y;
+          return localCenter.add(m.position);
+        });
+
+        const centerGLSL = `
+          vec3 getCenterOfMass(int idx) {
+            if (idx == 0) return vec3(${centers[0].x}, ${centers[0].y}, ${centers[0].z});
+            if (idx == 1) return vec3(${centers[1].x}, ${centers[1].y}, ${centers[1].z});
+            if (idx == 2) return vec3(${centers[2].x}, ${centers[2].y}, ${centers[2].z});
+            return vec3(0.0);
+          }
+        `;
+
+        meshes.forEach((m, i) => {
+          const { inTransition, isFadeIn, normT } = getTransitionState(time, dyno.dynoFloat(i), dyno.dynoFloat((i+1)%splatFiles.length), period);
+          m.worldModifier = getTransitionModifier(inTransition, isFadeIn, normT, dyno.dynoInt(i), time, centerGLSL, dyno.dynoBool(PARAMETERS.fixedMinScale), dyno.dynoFloat(PARAMETERS.waves));
+          m.updateGenerator();
+        });
+
+        return { splatMeshes: meshes, centerGLSL };
+      }
+
+      const { splatMeshes, centerGLSL } = await loadAssets();
+      const gui = new GUI();
+      gui.add(PARAMETERS, "speedMultiplier", 0.25, 4.0, 0.01);
+      gui.add(PARAMETERS, "objectRotation");
+      gui.add(PARAMETERS, "pause");
+      gui.add(PARAMETERS, "cameraRotation");
+      gui.add(PARAMETERS, "fixedMinScale").onChange(() => {
+        splatMeshes.forEach((m, i) => {
+          const { inTransition, isFadeIn, normT } = getTransitionState(time, dyno.dynoFloat(i), dyno.dynoFloat((i+1)%splatFiles.length), dyno.dynoFloat(splatFiles.length));
+          m.worldModifier = getTransitionModifier(inTransition, isFadeIn, normT, dyno.dynoInt(i), time, centerGLSL, dyno.dynoBool(PARAMETERS.fixedMinScale), dyno.dynoFloat(PARAMETERS.waves));
+          m.updateGenerator();
+        });
+      });
+      gui.add(PARAMETERS, "waves", 0, 1, 0.01).onChange(() => {
+        splatMeshes.forEach((m, i) => {
+          const { inTransition, isFadeIn, normT } = getTransitionState(time, dyno.dynoFloat(i), dyno.dynoFloat((i+1)%splatFiles.length), dyno.dynoFloat(splatFiles.length));
+          m.worldModifier = getTransitionModifier(inTransition, isFadeIn, normT, dyno.dynoInt(i), time, centerGLSL, dyno.dynoBool(PARAMETERS.fixedMinScale), dyno.dynoFloat(PARAMETERS.waves));
+          m.updateGenerator();
+        });
+      });
+
+      let last = 0;
+      renderer.setAnimationLoop(rt => {
+        const t = rt * 0.0005;
+        const dt = t - last;
+        last = t;
+        updateCamera(splatMeshes);
+        renderer.render(scene, camera);
+        if (!PARAMETERS.pause) {
+          time.value += dt * PARAMETERS.speedMultiplier;
+          if (PARAMETERS.objectRotation) splatMeshes.forEach(m => m.rotation.y += dt * PARAMETERS.speedMultiplier * 2);
+        }
+      });
+
+      function updateCamera(meshes) {
+        const cTime = 1 + PAUSE_SECONDS;
+        const tot = meshes.length * cTime;
+        const w = (time.value + PAUSE_SECONDS) % tot;
+        const cur = Math.floor(w / cTime);
+        const nxt = (cur + 1) % meshes.length;
+        const tr = w / cTime - cur;
+        const s = tr * tr * (3 - 2 * tr);
+        const tgt = new THREE.Vector3().lerpVectors(meshes[cur].position, meshes[nxt].position, s**5);
+
+        const radius = 4 + (Math.abs(s-0.5)**2)*20;
+        let x, z;
+
+        if (PARAMETERS.cameraRotation) {
+          const angle = -time.value * 0.5; // Velocidad de rotación
+          x = Math.cos(angle) * radius;
+          z = Math.sin(angle) * radius;
+        } else {
+          x = 0;
+          z = -radius;
+        }
+
+        const frm = tgt.clone().add(new THREE.Vector3(x, 2, z));
+        camera.position.copy(frm);
+        camera.lookAt(tgt);
+      }
+    </script>
+  </body>
+</html>