From: Patrick <patrick.schoenberger@posteo.de>
Date: Thu, 18 Mar 2021 16:05:15 +0000 (+0100)
Subject: comments
X-Git-Url: https://gitweb.ps.run/cloth_sim/commitdiff_plain/eac8eb4ec5115f16fc17b94fb194fdc1c005ddb5?ds=sidebyside

comments
---

diff --git a/Scripts/cloth.js b/Scripts/cloth.js
index 1f1c1e0..712ed63 100644
--- a/Scripts/cloth.js
+++ b/Scripts/cloth.js
@@ -5,10 +5,6 @@ const GRAVITY = new THREE.Vector3(0, -9.81 * MASS, 0);
 const K = 1;
 const MAX_STRETCH = 1.5;
 
-// Explosion am Anfang
-// Intersect mit Velocity?
-// Wind/Ziehen
-
 const options = {
   wind: true,
 };
@@ -21,22 +17,23 @@ class Spring {
   }
 
   satisfy() {
+    /** calculate current spring length */
     const diff = this.p2.position.clone().sub(this.p1.position);
     const currentDist = diff.length();
     if (currentDist == 0) return;
     if (currentDist <= this.restDist) return;
     //const correction = diff.multiplyScalar(1 - (this.restDist / currentDist));
+
+    /** calculate necessary correction length and direction */
     const correction = diff.multiplyScalar((currentDist - this.restDist) / currentDist);
     correction.multiplyScalar(K);
-    if (currentDist >= this.restDist * MAX_STRETCH) {
-
-    }
-    //correction.clampLength(0, 1);
     const correctionHalf = correction.multiplyScalar(0.5);
 
     let p1movable = this.p1.movable && this.p1.movableTmp;
     let p2movable = this.p2.movable && this.p2.movableTmp;
 
+    /** apply correction if masses aren't fixed */
+    /** divide correction if both are movable */
     if (p1movable && p2movable) {
       this.p1.position.add(correctionHalf);
       this.p2.position.sub(correctionHalf);
@@ -67,8 +64,11 @@ class Mass {
     // verlet algorithm
     // next position = 2 * current Position - previous position + acceleration * (passed time)^2
     // acceleration (dv/dt) = F(net)
+    /** calculate velocity */
     const nextPosition = this.position.clone().sub(this.previous);
+    /** apply drag */
     nextPosition.multiplyScalar(DRAG);
+    /** add to current position and add acceleration */
     nextPosition.add(this.position);
     nextPosition.add(this.acceleration.multiplyScalar(dt*dt));
 
@@ -77,6 +77,7 @@ class Mass {
       this.position = nextPosition;
     }
 
+    /** reset for next frame */
     this.acceleration.set(0, 0, 0);
   }
 }
@@ -114,18 +115,16 @@ class Cloth {
       }
     }
 
-    //this.masses[this.getVertexIndex(0, 0)].movable = false;
+    /** attach cloth to flag pole */
     const n = 3;
     for (let i = 0; i < numPointsHeight; i++)
       this.masses[this.getVertexIndex(0, i)].movable = false;
-    //this.masses[this.getVertexIndex(0, numPointsHeight-1)].movable = false;
-    //this.masses[this.getVertexIndex(numPointsWidth-1, 0)].movable = false;
 
     const REST_DIST_X = width / (numPointsWidth-1);
     const REST_DIST_Y = height / (numPointsHeight-1);
 
     /**
-     * generate springs (springs)
+     * generate springs (constraints)
      */
     this.springs = [];
     for (let y = 0; y < numPointsHeight; y++) {
@@ -154,6 +153,7 @@ class Cloth {
     const indices = [];
     const uvs = [];
 
+    /** create one vertex and one uv coordinate per mass */
     for (let i in this.masses) {
       let particle = this.masses[i];
       vertices.push(
@@ -185,6 +185,7 @@ class Cloth {
       }
     }
 
+    /** set up geometry */
     geometry.setIndex(indices);
     geometry.setAttribute('position', new THREE.Float32BufferAttribute(vertices, 3));
     geometry.setAttribute('uv', new THREE.Float32BufferAttribute(uvs, 2));
@@ -194,6 +195,7 @@ class Cloth {
     return geometry;
   }
   updateGeometry(geometry) {
+    /** update vertex positions in place */
     const positions = geometry.attributes.position.array;
     for (let i in this.masses) {
       let p = this.masses[i];
@@ -201,6 +203,7 @@ class Cloth {
       positions[i*3+1] = p.position.y;
       positions[i*3+2] = p.position.z;
     }
+    /** update internally and recalculate bounding volume */
     geometry.attributes.position.needsUpdate = true;
     geometry.computeBoundingSphere();
     geometry.computeVertexNormals();
@@ -208,6 +211,10 @@ class Cloth {
   simulate(dt) {
     let now = performance.now();
     for (let mass of this.masses) {
+      /** accumulate acceleration:
+       *  - wind
+       *  - gravity
+       */
       let vertex = mass.position;
       let fWind = new THREE.Vector3(
         this.windFactor.x * (Math.sin(vertex.x * vertex.y * now)+1),
@@ -221,14 +228,16 @@ class Cloth {
 
       mass.addForce(GRAVITY);
 
+      /** integrate motion */
       mass.verlet(dt);
     }
 
-    
+    /** run satisfy step */
     for (let constraint of this.springs) {
       constraint.satisfy();
     }
 
+    /** prevent self-intersections */
     this.intersect();
   }
 
@@ -241,15 +250,21 @@ class Cloth {
         p1.movableTmp = true;
         p2.movableTmp = true;
 
+        /** skip if i == j or if masses are adjacent */
         if (i == j || (Math.abs(this.getX(i) - this.getX(j)) == 1 && Math.abs(this.getY(i) - this.getY(j)) == 1))
           continue;
 
+        /** calculate distance of points  */
         let dist = p1.position.distanceTo(p2.position);
+        /** calculate minimal resting distance (largest distance that should not be fallen below) */
         let collisionDistance = Math.min(this.width / this.numPointsWidth, this.height / this.numPointsHeight);
         // collisionDistance /= 2;
+        /** calculate "sphere intersection" */
         if (dist < collisionDistance) {
           // p1.movableTmp = false;
           // p2.movableTmp = false;
+
+          /** vectors from p1 to p2 and the other way round */
           let diffP2P1 = p1.position.clone().sub(p2.position).normalize();
           diffP2P1.multiplyScalar((collisionDistance - dist) * 1.001 / 2);
           let diffP1P2 = diffP2P1.clone().multiplyScalar(-1);
@@ -260,6 +275,7 @@ class Cloth {
           // let factor1 = (Math.PI - Math.acos(v1.dot(diffP2P1))) / Math.PI * 2;
           // let factor2 = (Math.PI - Math.acos(v2.dot(diffP1P2))) / Math.PI * 2;
 
+          /** move masses apart */
           if (p1.movable)
             p1.position.add(diffP2P1);
             //p1.position.add(diffP2P1.multiplyScalar(factor1));
@@ -272,13 +288,17 @@ class Cloth {
   }
   blow(camPos, intersects) {
     let face = intersects[0].face;
+    /** vector from cam to intersection (wind) */
     let dir = intersects[0].point.clone().sub(camPos).multiplyScalar(100);
+    /** apply to all vertices of affected face */
     this.masses[face.a].addForce(dir);
     this.masses[face.b].addForce(dir);
     this.masses[face.c].addForce(dir);
   }
   drag(mousePosWorld, index) {
+    /** calculate vector from vertex to cursor */
     let dir = mousePosWorld.clone().sub(this.masses[index].position).multiplyScalar(200);
+    /** apply to grabbed vertex */
     this.masses[index].addForce(dir);
   }
 
diff --git a/Scripts/main.js b/Scripts/main.js
index 51d6762..1a30f7a 100644
--- a/Scripts/main.js
+++ b/Scripts/main.js
@@ -82,13 +82,15 @@ function init() {
   const loader = new THREE.TextureLoader();
   //Red color: 0xC70039
 
+  /** Create cloth and generate mesh */
   const cloth = new Cloth(1, 0.5, 20, 20);
   const clothGeometry = cloth.generateGeometry();
-  const clothMaterial = new THREE.MeshStandardMaterial({ map: loader.load('Textures/hsrm2.png'), color: {type: "c", value: new THREE.Color(0xffffff)}, side: THREE.DoubleSide, flatShading: false, transparent: true });
+  const clothMaterial = new THREE.MeshStandardMaterial({ map: loader.load('Textures/hsrm2.png'), color: 0xffffff, side: THREE.DoubleSide, flatShading: false });
   //const clothMaterial = new THREE.MeshStandardMaterial({ color: 0xC70039, side: THREE.DoubleSide, flatShading: false });
   const clothMesh = new THREE.Mesh(clothGeometry, clothMaterial);
   scene.add(clothMesh);
   
+  /** Register wind checkbox */
   document.getElementById("windToggle").checked = options.wind;
   document.getElementById("windToggle").onchange = (e) => {
     options.wind = e.target.checked;
@@ -104,25 +106,31 @@ function init() {
    * @param {number} dt - time passed since last frame in ms
    */
   function animate(dt) {
+    /** run simulation step */
     cloth.simulate(dt / 1000);
 
     cloth.updateGeometry(clothGeometry);
-    
-    raycaster.setFromCamera(new THREE.Vector2((mousePos.x / w) * 2 - 1, ((h - mousePos.y) / h) * 2 - 1), camera);
 
+    /** raycast from camera to cursor */
+    raycaster.setFromCamera(new THREE.Vector2((mousePos.x / w) * 2 - 1, ((h - mousePos.y) / h) * 2 - 1), camera);
     intersects = raycaster.intersectObject(clothMesh);
 
+    /** provide user interaction */
     if (intersects.length > 0) {
       if (windKeyDown)
         cloth.blow(camera.position, intersects);
+      /** "grab" vertex index */
       if (dragKeyDown && draggedIndex == -1)
         draggedIndex = intersects[0].face.a;
     }
     if (dragKeyDown && draggedIndex != -1)
       cloth.drag(calculateMousePosToWorld(mousePos), draggedIndex);
+
+    /** queue next frame */
     setTimeout(() => {
       animate(frameTime);
     }, frameTime);
+
     renderer.render(scene, camera);
   }
 
@@ -163,6 +171,7 @@ function init() {
     evt.preventDefault();
   }, false);
 
+  /** register key events */
   document.onkeydown = (evt) => {
     if (evt.code === "KeyW")
       windKeyDown = true;
@@ -179,6 +188,7 @@ function init() {
     }
   };
 
+  /** helper function to turn mouse position into 3D coordinates */
   function calculateMousePosToWorld(mousePos){
     var vec = new THREE.Vector3(); // create once and reuse
     var pos = new THREE.Vector3(); // create once and reuse