+++ /dev/null
-const DAMPING = 0.03;\r
-const DRAG = 1 - DAMPING;\r
-const MASS = 0.1;\r
-const GRAVITY = new THREE.Vector3(0, -9.81 * MASS, 0);\r
-const K = 1;\r
-const MAX_STRETCH = 1.5;\r
-\r
-const options = {\r
- wind: true,\r
-};\r
-\r
-class Spring {\r
- constructor(p1, p2, restDist) {\r
- this.p1 = p1;\r
- this.p2 = p2;\r
- this.restDist = restDist;\r
- }\r
-\r
- satisfy() {\r
- /** calculate current spring length */\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
-\r
- /** calculate necessary correction length and direction */\r
- const correction = diff.multiplyScalar((currentDist - this.restDist) / currentDist);\r
- correction.multiplyScalar(K);\r
- const correctionHalf = correction.multiplyScalar(0.5);\r
-\r
- let p1movable = this.p1.movable && this.p1.movableTmp;\r
- let p2movable = this.p2.movable && this.p2.movableTmp;\r
-\r
- /** apply correction if masses aren't fixed */\r
- /** divide correction if both are movable */\r
- if (p1movable && p2movable) {\r
- this.p1.position.add(correctionHalf);\r
- this.p2.position.sub(correctionHalf);\r
- } else if (! p1movable && p2movable) {\r
- this.p2.position.sub(correction);\r
- } else if (p1movable && ! p2movable) {\r
- this.p1.position.add(correction);\r
- }\r
- }\r
-}\r
-\r
-class Mass {\r
- movableTmp = true;\r
- movable = true;\r
-\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
- 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
- /** calculate velocity */\r
- const nextPosition = this.position.clone().sub(this.previous);\r
- /** apply drag */\r
- nextPosition.multiplyScalar(DRAG);\r
- /** add to current position and add acceleration */\r
- nextPosition.add(this.position);\r
- nextPosition.add(this.acceleration.multiplyScalar(dt*dt));\r
-\r
- if (this.movable && this.movableTmp) {\r
- this.previous = this.position;\r
- this.position = nextPosition;\r
- }\r
-\r
- /** reset for next frame */\r
- this.acceleration.set(0, 0, 0);\r
- }\r
-}\r
-\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(3, 2, 2);\r
-\r
- /**\r
- * distance between two vertices horizontally/vertically\r
- * divide by the number of points minus one\r
- * because there are (n - 1) lines between n vertices\r
- */\r
- let stepWidth = width / (numPointsWidth - 1);\r
- let stepHeight = height / (numPointsHeight - 1);\r
-\r
- /**\r
- * iterate over the number of vertices in x/y axis\r
- * and add a new Particle to "masses"\r
- */\r
- this.masses = [];\r
- for (let y = 0; y < numPointsHeight; y++) {\r
- for (let x = 0; x < numPointsWidth; x++) {\r
- this.masses.push(\r
- new Mass(\r
- (x - ((numPointsWidth-1)/2)) * stepWidth,\r
- height - (y + ((numPointsHeight-1)/2)) * stepHeight,\r
- 0,\r
- MASS)\r
- );\r
- }\r
- }\r
-\r
- /** attach cloth to flag pole */\r
- const n = 3;\r
- for (let i = 0; i < numPointsHeight; i++)\r
- this.masses[this.getVertexIndex(0, i)].movable = false;\r
-\r
- const REST_DIST_X = width / (numPointsWidth-1);\r
- const REST_DIST_Y = height / (numPointsHeight-1);\r
-\r
- /**\r
- * generate springs (constraints)\r
- */\r
- this.springs = [];\r
- for (let y = 0; y < numPointsHeight; y++) {\r
- for (let x = 0; x < numPointsWidth; x++) {\r
- if (x < numPointsWidth-1) {\r
- this.springs.push(new Spring(\r
- this.masses[this.getVertexIndex(x, y)],\r
- this.masses[this.getVertexIndex(x+1, y)],\r
- REST_DIST_X\r
- ));\r
- }\r
- if (y < numPointsHeight-1) {\r
- this.springs.push(new Spring(\r
- this.masses[this.getVertexIndex(x, y)],\r
- this.masses[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 indices = [];\r
- const uvs = [];\r
-\r
- /** create one vertex and one uv coordinate per mass */\r
- for (let i in this.masses) {\r
- let particle = this.masses[i];\r
- vertices.push(\r
- particle.position.x,\r
- particle.position.y,\r
- particle.position.z);\r
- uvs.push(\r
- this.getX(i) / (this.numPointsWidth-1),\r
- 1 - (this.getY(i) / (this.numPointsHeight-1))\r
- );\r
- }\r
-\r
- /**\r
- * generate faces based on 4 vertices\r
- * and 6 springs each\r
- */\r
- for (let y = 0; y < this.numPointsHeight - 1; y++) {\r
- for (let x = 0; x < this.numPointsWidth - 1; x++) {\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
- }\r
-\r
- /** set up geometry */\r
- geometry.setIndex(indices);\r
- geometry.setAttribute('position', new THREE.Float32BufferAttribute(vertices, 3));\r
- geometry.setAttribute('uv', new THREE.Float32BufferAttribute(uvs, 2));\r
- geometry.computeBoundingSphere();\r
- geometry.computeVertexNormals();\r
-\r
- return geometry;\r
- }\r
- updateGeometry(geometry) {\r
- /** update vertex positions in place */\r
- const positions = geometry.attributes.position.array;\r
- for (let i in this.masses) {\r
- let p = this.masses[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
- /** update internally and recalculate bounding volume */\r
- geometry.attributes.position.needsUpdate = true;\r
- geometry.computeBoundingSphere();\r
- geometry.computeVertexNormals();\r
- }\r
- simulate(dt) {\r
- let now = performance.now();\r
- for (let mass of this.masses) {\r
- /** accumulate acceleration:\r
- * - wind\r
- * - gravity\r
- */\r
- let vertex = mass.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
- mass.addForce(fWind);\r
- // calculate wind with normal?\r
-\r
- mass.addForce(GRAVITY);\r
-\r
- /** integrate motion */\r
- mass.verlet(dt);\r
- }\r
-\r
- /** run satisfy step */\r
- for (let constraint of this.springs) {\r
- constraint.satisfy();\r
- }\r
-\r
- /** prevent self-intersections */\r
- this.intersect();\r
- }\r
-\r
- intersect() {\r
- for (let i in this.masses) {\r
- for (let j in this.masses) { \r
- let p1 = this.masses[i];\r
- let p2 = this.masses[j];\r
-\r
- p1.movableTmp = true;\r
- p2.movableTmp = true;\r
-\r
- /** skip if i == j or if masses are adjacent */\r
- if (i == j || (Math.abs(this.getX(i) - this.getX(j)) == 1 && Math.abs(this.getY(i) - this.getY(j)) == 1))\r
- continue;\r
-\r
- /** calculate distance of points */\r
- let dist = p1.position.distanceTo(p2.position);\r
- /** calculate minimal resting distance (largest distance that should not be fallen below) */\r
- let collisionDistance = Math.min(this.width / this.numPointsWidth, this.height / this.numPointsHeight);\r
- // collisionDistance /= 2;\r
- /** calculate "sphere intersection" */\r
- if (dist < collisionDistance) {\r
- // p1.movableTmp = false;\r
- // p2.movableTmp = false;\r
-\r
- /** vectors from p1 to p2 and the other way round */\r
- let diffP2P1 = p1.position.clone().sub(p2.position).normalize();\r
- diffP2P1.multiplyScalar((collisionDistance - dist) * 1.001 / 2);\r
- let diffP1P2 = diffP2P1.clone().multiplyScalar(-1);\r
-\r
- // let v1 = p1.position.clone().sub(p1.previous).normalize();\r
- // let v2 = p2.position.clone().sub(p2.previous).normalize();\r
-\r
- // let factor1 = (Math.PI - Math.acos(v1.dot(diffP2P1))) / Math.PI * 2;\r
- // let factor2 = (Math.PI - Math.acos(v2.dot(diffP1P2))) / Math.PI * 2;\r
-\r
- /** move masses apart */\r
- if (p1.movable)\r
- p1.position.add(diffP2P1);\r
- //p1.position.add(diffP2P1.multiplyScalar(factor1));\r
- if (p2.movable)\r
- p2.position.add(diffP1P2);\r
- //p2.position.add(diffP1P2.multiplyScalar(factor2));\r
- }\r
- }\r
- }\r
- }\r
- blow(camPos, intersects) {\r
- let face = intersects[0].face;\r
- /** vector from cam to intersection (wind) */\r
- let dir = intersects[0].point.clone().sub(camPos).multiplyScalar(100);\r
- /** apply to all vertices of affected face */\r
- this.masses[face.a].addForce(dir);\r
- this.masses[face.b].addForce(dir);\r
- this.masses[face.c].addForce(dir);\r
- }\r
- drag(mousePosWorld, index) {\r
- /** calculate vector from vertex to cursor */\r
- let dir = mousePosWorld.clone().sub(this.masses[index].position).multiplyScalar(200);\r
- /** apply to grabbed vertex */\r
- this.masses[index].addForce(dir);\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
- getX(i) { return i % this.numPointsWidth; }\r
- getY(i) { return Math.floor(i / this.numPointsWidth); }\r
-}
\ No newline at end of file
projects / cloth_sim / blobdiff