-/**\r
- * Convenience Function for calculating the distance between two vectors\r
- * because THREE JS Vector functions mutate variables\r
- * @param {Vector3} a - Vector A\r
- * @param {Vector3} b - Vector B\r
- */\r
-function vectorLength(a, b) {\r
- let v1 = new THREE.Vector3();\r
- v1.copy(a);\r
- let v2 = new THREE.Vector3();\r
- v2.copy(b);\r
-\r
- return v1.sub(v2).length();\r
-}\r
-\r
-/**\r
- * Class representing a quad face\r
- * Each face consists of two triangular mesh faces\r
- * containts four indices for determining vertices\r
- * and six springs, one between each of the vertices\r
- */\r
-export class Face {\r
- a;\r
- b;\r
- c;\r
- d;\r
-\r
- springs = [];\r
+const DAMPING = 0.03;\r
+const DRAG = 1 - DAMPING;\r
+const MASS = 0.35;\r
+const GRAVITY = new THREE.Vector3(0, -9.81 * MASS, 0);\r
+const K = 1;\r
+\r
+const options = {\r
+ wind: true,\r
+};\r
+\r
+class Constraint {\r
+ constructor(p1, p2, restDist) {\r
+ this.p1 = p1;\r
+ this.p2 = p2;\r
+ this.restDist = restDist;\r
+ }\r
\r
- constructor(a, b, c, d) {\r
- this.a = a;\r
- this.b = b;\r
- this.c = c;\r
- this.d = d;\r
+ satisfy() {\r
+ const diff = this.p2.position.clone().sub(this.p1.position);\r
+ const currentDist = diff.length();\r
+ if (currentDist == 0) return;\r
+ if (currentDist <= this.restDist) return;\r
+ //const correction = diff.multiplyScalar(1 - (this.restDist / currentDist));\r
+ const correction = diff.multiplyScalar((currentDist - this.restDist) / currentDist);\r
+ correction.multiplyScalar(K);\r
+ correction.clampLength(0, 1);\r
+ const correctionHalf = correction.multiplyScalar(0.5);\r
+ if (this.p1.movable && this.p2.movable) {\r
+ this.p1.position.add(correctionHalf);\r
+ this.p2.position.sub(correctionHalf);\r
+ } else if (! this.p1.movable && this.p2.movable) {\r
+ this.p2.position.sub(correction);\r
+ } else if (this.p1.movable && ! this.p2.movable) {\r
+ this.p1.position.add(correction);\r
+ }\r
}\r
}\r
\r
-/**\r
- * Class representing a single spring\r
- * has a current and resting length\r
- * and indices to the two connected vertices\r
- */\r
-export class Spring {\r
- restLength;\r
- currentLength;\r
- index1;\r
- index2;\r
+class Particle {\r
+ movable = true;\r
\r
-\r
- /**\r
- * set vertex indices\r
- * and calculate inital length based on the\r
- * vertex positions\r
- * @param {Array<Vector3>} vertices \r
- * @param {number} index1 \r
- * @param {number} index2 \r
- */\r
- constructor(vertices, index1, index2) {\r
- this.index1 = index1;\r
- this.index2 = index2;\r
-\r
- let length = vectorLength(vertices[index1], vertices[index2]);\r
- this.restLength = length;\r
- this.currentLength = length;\r
+ constructor(x, y, z, mass) {\r
+ this.position = new THREE.Vector3(x, y, z);\r
+ this.previous = new THREE.Vector3(x, y, z);\r
+ this.acceleration = new THREE.Vector3(0, 0, 0);\r
+ this.mass = mass;\r
}\r
-\r
- getDirection(vertices) {\r
- let direction = new THREE.Vector3();\r
- direction.copy(vertices[this.index1]);\r
-\r
- direction.sub(vertices[this.index2]);\r
- direction.divideScalar(vectorLength(vertices[this.index1], vertices[this.index2]));\r
-\r
- return direction;\r
+ addForce(force) {\r
+ this.acceleration.add(\r
+ force.clone().multiplyScalar(1/this.mass)\r
+ );\r
}\r
+ verlet(dt) {\r
+ // verlet algorithm\r
+ // next position = 2 * current Position - previous position + acceleration * (passed time)^2\r
+ // acceleration (dv/dt) = F(net)\r
+ const nextPosition = this.position.clone().sub(this.previous);\r
+ nextPosition.multiplyScalar(DRAG);\r
+ nextPosition.add(this.position);\r
+ nextPosition.add(this.acceleration.multiplyScalar(dt*dt));\r
+\r
+ if (this.movable) {\r
+ this.previous = this.position;\r
+ this.position = nextPosition;\r
+ }\r
\r
- update(vertices) {\r
- let length = vectorLength(vertices[this.index1], vertices[this.index2]);\r
- this.currentLength = length;\r
+ this.acceleration.set(0, 0, 0);\r
}\r
}\r
\r
-/**\r
- * Class representing a single piece of cloth\r
- * contains THREE JS geometry,\r
- * logically represented by an array of adjacent faces\r
- * and vertex weights which are accessed by the same\r
- * indices as the vertices in the Mesh\r
- */\r
-export class Cloth {\r
- VertexWeight = 1;\r
-\r
- geometry = new THREE.Geometry();\r
-\r
- faces = [];\r
-\r
- vertexWeights = [];\r
-\r
- vertexRigidness = [];\r
-\r
- /**\r
- * creates a rectangular piece of cloth\r
- * takes the size of the cloth\r
- * and the number of vertices it should be composed of\r
- * @param {number} width - width of the cloth\r
- * @param {number} height - height of the cloth\r
- * @param {number} numPointsWidth - number of vertices in horizontal direction\r
- * @param {number} numPointsHeight - number of vertices in vertical direction\r
- */\r
- createBasic(width, height, numPointsWidth, numPointsHeight) {\r
- /** resulting vertices and faces */\r
- let vertices = [];\r
- let faces = [];\r
+class Cloth {\r
+ constructor(width, height, numPointsWidth, numPointsHeight) {\r
+ this.width = width;\r
+ this.height = height;\r
+ this.numPointsWidth = numPointsWidth;\r
+ this.numPointsHeight = numPointsHeight;\r
+ this.windFactor = new THREE.Vector3(5, 2, 2);\r
\r
/**\r
* distance between two vertices horizontally/vertically\r
\r
/**\r
* iterate over the number of vertices in x/y axis\r
- * and add a new Vector3 to "vertices"\r
+ * and add a new Particle to "particles"\r
*/\r
+ this.particles = [];\r
for (let y = 0; y < numPointsHeight; y++) {\r
for (let x = 0; x < numPointsWidth; x++) {\r
- vertices.push(\r
- new THREE.Vector3(x * stepWidth, height - y * stepHeight, 0)\r
+ this.particles.push(\r
+ new Particle(\r
+ (x - ((numPointsWidth-1)/2)) * stepWidth,\r
+ height - (y + ((numPointsHeight-1)/2)) * stepHeight,\r
+ 0,\r
+ MASS)\r
);\r
}\r
}\r
\r
+ //this.particles[this.getVertexIndex(0, 0)].movable = false;\r
+ const n = 3;\r
+ for (let i = 0; i <= n; i++)\r
+ this.particles[this.getVertexIndex(0, Math.floor((numPointsHeight-1)*(i/n)))].movable = false;\r
+ //this.particles[this.getVertexIndex(0, numPointsHeight-1)].movable = false;\r
+ //this.particles[this.getVertexIndex(numPointsWidth-1, 0)].movable = false;\r
+\r
+ const REST_DIST_X = width / (numPointsWidth-1);\r
+ const REST_DIST_Y = height / (numPointsHeight-1);\r
+\r
/**\r
- * helper function to calculate index of vertex\r
- * in "vertices" array based on its x and y positions\r
- * in the mesh\r
- * @param {number} x - x index of vertex\r
- * @param {number} y - y index of vertex\r
+ * generate constraints (springs)\r
*/\r
- function getVertexIndex(x, y) {\r
- return y * numPointsWidth + x;\r
+ this.constraints = [];\r
+ for (let y = 0; y < numPointsHeight; y++) {\r
+ for (let x = 0; x < numPointsWidth; x++) {\r
+ if (x < numPointsWidth-1) {\r
+ this.constraints.push(new Constraint(\r
+ this.particles[this.getVertexIndex(x, y)],\r
+ this.particles[this.getVertexIndex(x+1, y)],\r
+ REST_DIST_X\r
+ ));\r
+ }\r
+ if (y < numPointsHeight-1) {\r
+ this.constraints.push(new Constraint(\r
+ this.particles[this.getVertexIndex(x, y)],\r
+ this.particles[this.getVertexIndex(x, y+1)],\r
+ REST_DIST_Y\r
+ ));\r
+ }\r
+ }\r
+ }\r
+ }\r
+ generateGeometry() {\r
+ const geometry = new THREE.BufferGeometry();\r
+\r
+ const vertices = [];\r
+ const normals = [];\r
+ const indices = [];\r
+\r
+ for (let particle of this.particles) {\r
+ vertices.push(\r
+ particle.position.x,\r
+ particle.position.y,\r
+ particle.position.z);\r
}\r
\r
+ const numPointsWidth = this.numPointsWidth;\r
+ const numPointsHeight = this.numPointsHeight;\r
+\r
/**\r
* generate faces based on 4 vertices\r
* and 6 springs each\r
*/\r
for (let y = 0; y < numPointsHeight - 1; y++) {\r
for (let x = 0; x < numPointsWidth - 1; x++) {\r
- let newFace = new Face(\r
- getVertexIndex(x, y),\r
- getVertexIndex(x, y + 1),\r
- getVertexIndex(x + 1, y),\r
- getVertexIndex(x + 1, y + 1),\r
+ indices.push(\r
+ this.getVertexIndex(x, y),\r
+ this.getVertexIndex(x+1, y),\r
+ this.getVertexIndex(x+1, y+1)\r
+ );\r
+ indices.push(\r
+ this.getVertexIndex(x, y),\r
+ this.getVertexIndex(x+1, y+1),\r
+ this.getVertexIndex(x, y+1)\r
);\r
-\r
- newFace.springs.push(new Spring(vertices, getVertexIndex(x, y), getVertexIndex(x + 1, y)));\r
- newFace.springs.push(new Spring(vertices, getVertexIndex(x, y), getVertexIndex(x, y + 1)));\r
- newFace.springs.push(new Spring(vertices, getVertexIndex(x, y), getVertexIndex(x + 1, y + 1)));\r
- newFace.springs.push(new Spring(vertices, getVertexIndex(x + 1, y), getVertexIndex(x, y + 1)));\r
- newFace.springs.push(new Spring(vertices, getVertexIndex(x + 1, y), getVertexIndex(x + 1, y + 1)));\r
- newFace.springs.push(new Spring(vertices, getVertexIndex(x, y + 1), getVertexIndex(x + 1, y + 1)));\r
-\r
- faces.push(newFace);\r
}\r
}\r
\r
- /**\r
- * call createExplicit\r
- * with generated vertices and faces\r
- */\r
- this.createExplicit(vertices, faces);\r
+ geometry.setIndex(indices);\r
+ geometry.setAttribute('position', new THREE.Float32BufferAttribute(vertices, 3));\r
+ //geometry.setAttribute('normal', new THREE.Float32BufferAttribute(normals, 3));\r
+ geometry.computeBoundingSphere();\r
+ geometry.computeVertexNormals();\r
\r
- /**\r
- * hand cloth from left and right upper corners\r
- */\r
- this.vertexRigidness[0] = true;\r
- this.vertexRigidness[numPointsWidth-1] = true;\r
+ return geometry;\r
}\r
-\r
- /**\r
- * Generate THREE JS Geometry\r
- * (list of vertices and list of indices representing triangles)\r
- * and calculate the weight of each face and split it between\r
- * surrounding vertices\r
- * @param {Array<Vector3>} vertices \r
- * @param {Array<Face>} faces \r
- */\r
- createExplicit(vertices, faces) {\r
-\r
- /**\r
- * Copy vertices and initialize vertex weights to 0\r
- */\r
- for (let i in vertices) {\r
- this.geometry.vertices.push(vertices[i].clone());\r
- this.previousPositions.push(vertices[i].clone());\r
- // this.geometry.vertices.push(vertices[i]);\r
- // this.previousPositions.push(vertices[i]);\r
- this.vertexWeights.push(0);\r
- this.vertexRigidness.push(false);\r
+ updateGeometry(geometry) {\r
+ const positions = geometry.attributes.position.array;\r
+ for (let i in this.particles) {\r
+ let p = this.particles[i];\r
+ positions[i*3+0] = p.position.x;\r
+ positions[i*3+1] = p.position.y;\r
+ positions[i*3+2] = p.position.z;\r
}\r
- /**\r
- * copy faces,\r
- * generate two triangles per face,\r
- * calculate weight of face as its area\r
- * and split between the 4 vertices\r
- */\r
- for (let i in faces) {\r
- let face = faces[i];\r
-\r
- /** copy faces to class member */\r
- this.faces.push(face);\r
-\r
- /** generate triangles */\r
- this.geometry.faces.push(new THREE.Face3(\r
- face.a, face.b, face.c\r
- ));\r
- this.geometry.faces.push(new THREE.Face3(\r
- face.c, face.b, face.d\r
- ));\r
-\r
- /**\r
- * calculate area of face as combined area of\r
- * its two composing triangles\r
- */\r
- let xLength = vectorLength(this.geometry.vertices[face.b], this.geometry.vertices[face.a]);\r
- let yLength = vectorLength(this.geometry.vertices[face.c], this.geometry.vertices[face.a]);\r
- let weight = xLength * yLength / 2;\r
-\r
- xLength = vectorLength(this.geometry.vertices[face.b], this.geometry.vertices[face.d]);\r
- yLength = vectorLength(this.geometry.vertices[face.c], this.geometry.vertices[face.d]);\r
- weight += xLength * yLength / 2;\r
-\r
- /**\r
- * split weight equally between four surrounding vertices\r
- */\r
- this.vertexWeights[face.a] += weight / 4;\r
- this.vertexWeights[face.b] += weight / 4;\r
- this.vertexWeights[face.c] += weight / 4;\r
- this.vertexWeights[face.d] += weight / 4;\r
- }\r
-\r
- /**\r
- * let THREE JS compute bounding sphere around generated mesh\r
- * needed for View Frustum Culling internally\r
- */\r
- this.geometry.computeBoundingSphere();\r
+ geometry.attributes.position.needsUpdate = true;\r
+ geometry.computeBoundingSphere();\r
+ geometry.computeVertexNormals();\r
}\r
-\r
- /**\r
- * generate a debug mesh for visualizing\r
- * vertices and springs of the cloth\r
- * and add it to scene for rendering\r
- * @param {Scene} scene - Scene to add Debug Mesh to\r
- */\r
- createDebugMesh(scene) {\r
- /**\r
- * helper function to generate a single line\r
- * between two Vertices with a given color\r
- * @param {Vector3} from \r
- * @param {Vector3} to \r
- * @param {number} color \r
- */\r
- function addLine(from, to, color) {\r
- let geometry = new THREE.Geometry();\r
- geometry.vertices.push(from);\r
- geometry.vertices.push(to);\r
- let material = new THREE.LineBasicMaterial({ color: color, linewidth: 10 });\r
- let line = new THREE.Line(geometry, material);\r
- line.renderOrder = 1;\r
- scene.add(line);\r
- }\r
- /**\r
- * helper function to generate a small sphere\r
- * at a given Vertex Position with color\r
- * @param {Vector3} point \r
- * @param {number} color \r
- */\r
- function addPoint(point, color) {\r
- const geometry = new THREE.SphereGeometry(0.05, 32, 32);\r
- const material = new THREE.MeshBasicMaterial({ color: color });\r
- const sphere = new THREE.Mesh(geometry, material);\r
- sphere.position.set(point.x, point.y, point.z);\r
- scene.add(sphere);\r
- }\r
-\r
- let lineColor = 0x000000;\r
- let pointColor = 0xff00000;\r
-\r
- /**\r
- * generate one line for each of the 6 springs\r
- * and one point for each of the 4 vertices\r
- * for all of the faces\r
- */\r
- for (let i in this.faces) {\r
- let face = this.faces[i];\r
- addLine(this.geometry.vertices[face.a], this.geometry.vertices[face.b], lineColor);\r
- addLine(this.geometry.vertices[face.a], this.geometry.vertices[face.c], lineColor);\r
- addLine(this.geometry.vertices[face.a], this.geometry.vertices[face.d], lineColor);\r
- addLine(this.geometry.vertices[face.b], this.geometry.vertices[face.c], lineColor);\r
- addLine(this.geometry.vertices[face.b], this.geometry.vertices[face.d], lineColor);\r
- addLine(this.geometry.vertices[face.c], this.geometry.vertices[face.d], lineColor);\r
-\r
- addPoint(this.geometry.vertices[face.a], pointColor);\r
- addPoint(this.geometry.vertices[face.b], pointColor);\r
- addPoint(this.geometry.vertices[face.c], pointColor);\r
- addPoint(this.geometry.vertices[face.d], pointColor);\r
- }\r
- }\r
-\r
- previousPositions = [];\r
- time = 0;\r
- /**\r
- * \r
- * @param {number} dt time in seconds since last frame\r
- */\r
simulate(dt) {\r
- for (let i in this.geometry.vertices) {\r
- let acceleration = this.getAcceleration(i, dt);\r
-\r
- //acceleration.clampLength(0, 10);\r
-\r
- if (Math.abs(acceleration.length()) <= 10e-4) {\r
- acceleration.set(0, 0, 0);\r
- }\r
- \r
- let currentPosition = this.verlet(this.geometry.vertices[i].clone(), this.previousPositions[i].clone(), acceleration, dt);\r
- //let currentPosition = this.euler(this.geometry.vertices[i], acceleration, dt);\r
- \r
- this.previousPositions[i].copy(this.geometry.vertices[i]);\r
- this.geometry.vertices[i].copy(currentPosition);\r
+ let now = performance.now();\r
+ for (let particle of this.particles) {\r
+ let vertex = particle.position;\r
+ let fWind = new THREE.Vector3(\r
+ this.windFactor.x * (Math.sin(vertex.x * vertex.y * now)+1),\r
+ this.windFactor.y * Math.cos(vertex.z * now),\r
+ this.windFactor.z * Math.sin(Math.cos(5 * vertex.x * vertex.y * vertex.z))\r
+ );\r
+ // normalize then multiply?\r
+ if (options.wind)\r
+ particle.addForce(fWind);\r
+ // calculate wind with normal?\r
+\r
+ particle.addForce(GRAVITY);\r
+\r
+ particle.verlet(dt);\r
}\r
- //console.log(this.getAcceleration(1, dt));\r
- \r
- this.time += dt;\r
\r
- for (let face of this.faces) {\r
- for (let spring of face.springs) {\r
- spring.update(this.geometry.vertices);\r
- }\r
+ \r
+ for (let constraint of this.constraints) {\r
+ constraint.satisfy();\r
}\r
-\r
- /**\r
- * let THREE JS compute bounding sphere around generated mesh\r
- * needed for View Frustum Culling internally\r
- */\r
-\r
- this.geometry.verticesNeedUpdate = true;\r
- this.geometry.elementsNeedUpdate = true;\r
- this.geometry.computeBoundingSphere();\r
-\r
+ //console.log(tmpCorrection);\r
}\r
-\r
-\r
-\r
-/**\r
- * Equation of motion for each vertex which represents the acceleration \r
- * @param {number} vertexIndex The index of the current vertex whose acceleration should be calculated\r
- * @param {number} dt The time passed since last frame\r
- */\r
-getAcceleration(vertexIndex, dt) {\r
- if (this.vertexRigidness[vertexIndex])\r
- return new THREE.Vector3(0, 0, 0);\r
-\r
- let vertex = this.geometry.vertices[vertexIndex];\r
-\r
- // Mass of vertex\r
- let M = this.vertexWeights[vertexIndex];\r
- // constant gravity\r
- let g = new THREE.Vector3(0, -9.8, 0);\r
- // stiffness\r
- let k = 1000;\r
-\r
- // Wind vector\r
- let fWind = new THREE.Vector3(\r
- Math.sin(vertex.x * vertex.y * this.time),\r
- Math.cos(vertex.z * this.time),\r
- Math.sin(Math.cos(5 * vertex.x * vertex.y * vertex.z))\r
- );\r
- fWind.set(0, 0, 0);\r
-\r
/**\r
- * constant determined by the properties of the surrounding fluids (air)\r
- * achievement of cloth effects through try out\r
- * */\r
- let a = 0.01;\r
-\r
- let velocity = new THREE.Vector3(\r
- (this.previousPositions[vertexIndex].x - vertex.x) / dt,\r
- (this.previousPositions[vertexIndex].y - vertex.y) / dt,\r
- (this.previousPositions[vertexIndex].z - vertex.z) / dt\r
- );\r
-\r
- //console.log(velocity, vertex, this.previousPositions[vertexIndex]);\r
-\r
- let fAirResistance = velocity.cross(velocity).multiplyScalar(-a);\r
-\r
- let springSum = new THREE.Vector3(0, 0, 0);\r
-\r
- // Get the bounding springs and add them to the needed springs\r
- // TODO: optimize\r
- for (let i in this.faces) {\r
- if (this.faces[i].a == vertexIndex || this.faces[i].b == vertexIndex || this.faces[i].c == vertexIndex || this.faces[i].d == vertexIndex) {\r
- for (let j in this.faces[i].springs) {\r
- if (this.faces[i].springs[j].index1 == vertexIndex || this.faces[i].springs[j].index2 == vertexIndex) {\r
-\r
- let spring = this.faces[i].springs[j];\r
- let springDirection = spring.getDirection(this.geometry.vertices);\r
-\r
-\r
- if (this.faces[i].springs[j].index1 == vertexIndex)\r
- springDirection.multiplyScalar(-1);\r
-\r
- springSum.add(springDirection.multiplyScalar(k * (spring.restLength - spring.currentLength)));\r
- }\r
- }\r
- }\r
+ * helper function to calculate index of vertex\r
+ * in "vertices" array based on its x and y positions\r
+ * in the mesh\r
+ * @param {number} x - x index of vertex\r
+ * @param {number} y - y index of vertex\r
+ */\r
+ getVertexIndex(x, y) {\r
+ return y * this.numPointsWidth + x;\r
}\r
- \r
- let result = new THREE.Vector3(1, 1, 1);\r
-\r
- result.multiplyScalar(M).multiply(g).add(fWind).add(fAirResistance).sub(springSum);\r
- \r
- return result;\r
-}\r
-\r
-/**\r
- * The Verlet algorithm as an integrator \r
- * to get the next position of a vertex \r
- * @param {Vector3} currentPosition \r
- * @param {Vector3} previousPosition \r
- * @param {Vector3} acceleration \r
- * @param {number} passedTime The delta time since last frame\r
- */\r
-verlet(currentPosition, previousPosition, acceleration, passedTime) {\r
- // verlet algorithm\r
- // next position = 2 * current Position - previous position + acceleration * (passed time)^2\r
- // acceleration (dv/dt) = F(net)\r
- // Dependency for one vertex: gravity, fluids/air, springs\r
-\r
- let nextPosition = new THREE.Vector3(\r
- (2 * currentPosition.x) - previousPosition.x + acceleration.x * (passedTime * passedTime),\r
- (2 * currentPosition.y) - previousPosition.y + acceleration.y * (passedTime * passedTime),\r
- (2 * currentPosition.z) - previousPosition.z + acceleration.z * (passedTime * passedTime),\r
- );\r
-\r
- return nextPosition;\r
-}\r
-\r
-euler(currentPosition, acceleration, passedTime) {\r
- let nextPosition = new THREE.Vector3(\r
- currentPosition.x + acceleration.x * passedTime,\r
- currentPosition.y + acceleration.y * passedTime,\r
- currentPosition.z + acceleration.z * passedTime,\r
- );\r
-\r
- return nextPosition;\r
-}\r
-\r
-}\r
-\r
+}
\ No newline at end of file
projects / cloth_sim / blobdiff