From fcfb3d929c2fefdfdcb6cb9351bcdd0d2d14f9f2 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Patrick=20Sch=C3=B6nberger?= Date: Wed, 6 Jan 2021 10:25:08 +0100 Subject: [PATCH] add cloth.js file --- Scripts/cloth.js | 285 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 285 insertions(+) create mode 100644 Scripts/cloth.js diff --git a/Scripts/cloth.js b/Scripts/cloth.js new file mode 100644 index 0000000..e84facc --- /dev/null +++ b/Scripts/cloth.js @@ -0,0 +1,285 @@ +/** + * Convenience Function for calculating the distance between two vectors + * because THREE JS Vector functions mutate variables + * @param {Vector3} a - Vector A + * @param {Vector3} b - Vector B + */ +function vectorLength(a, b) { + let v1 = new THREE.Vector3(); + v1.set(a.x, a.y, a.z); + let v2 = new THREE.Vector3(); + v2.set(b.x, b.y, b.z); + + return v1.sub(v2).length(); +} + +/** + * Class representing a quad face + * Each face consists of two triangular mesh faces + * containts four indices for determining vertices + * and six springs, one between each of the vertices + */ +export class Face { + a; + b; + c; + d; + + springs = []; + + constructor(a, b, c, d) { + this.a = a; + this.b = b; + this.c = c; + this.d = d; + } +} + +/** + * Class representing a single spring + * has a current and resting length + * and indices to the two connected vertices + */ +export class Spring { + restLength; + currentLength; + index1; + index2; + + + /** + * set vertex indices + * and calculate inital length based on the + * vertex positions + * @param {Array of Vector3} vertices + * @param {number} index1 + * @param {number} index2 + */ + constructor(vertices, index1, index2) { + this.index1 = index1; + this.index2 = index2; + + let length = vectorLength(vertices[index1], vertices[index2]); + this.restLength = length; + this.currentLength = length; + } +} + +/** + * Class representing a single piece of cloth + * contains THREE JS geometry, + * logically represented by an array of adjacent faces + * and vertex weights which are accessed by the same + * indices as the vertices in the Mesh + */ +export class Cloth { + VertexWeight = 1; + + geometry = new THREE.Geometry(); + + faces = []; + + vertexWeights = []; + + + /** + * creates a rectangular piece of cloth + * takes the size of the cloth + * and the number of vertices it should be composed of + * @param {number} width - width of the cloth + * @param {number} height - height of the cloth + * @param {number} numPointsWidth - number of vertices in horizontal direction + * @param {number} numPointsHeight - number of vertices in vertical direction + */ + createBasic(width, height, numPointsWidth, numPointsHeight) { + /** resulting vertices and faces */ + let vertices = []; + let faces = []; + + /** + * distance between two vertices horizontally/vertically + * divide by the number of points minus one + * because there are (n - 1) lines between n vertices + */ + let stepWidth = width / (numPointsWidth - 1); + let stepHeight = height / (numPointsHeight - 1); + + /** + * iterate over the number of vertices in x/y axis + * and add a new Vector3 to "vertices" + */ + for (let y = 0; y < numPointsHeight; y++) { + for (let x = 0; x < numPointsWidth; x++) { + vertices.push( + new THREE.Vector3(x * stepWidth, height - y * stepHeight, 0) + ); + } + } + + /** + * helper function to calculate index of vertex + * in "vertices" array based on its x and y positions + * in the mesh + * @param {number} x - x index of vertex + * @param {number} y - y index of vertex + */ + function getVertexIndex(x, y) { + return y * numPointsWidth + x; + } + + /** + * generate faces based on 4 vertices + * and 6 springs each + */ + for (let y = 0; y < numPointsHeight - 1; y++) { + for (let x = 0; x < numPointsWidth - 1; x++) { + let newFace = new Face( + getVertexIndex(x, y), + getVertexIndex(x, y + 1), + getVertexIndex(x + 1, y), + getVertexIndex(x + 1, y + 1), + ); + + newFace.springs.push(new Spring(vertices, getVertexIndex(x, y), getVertexIndex(x + 1, y))); + newFace.springs.push(new Spring(vertices, getVertexIndex(x, y), getVertexIndex(x, y + 1))); + newFace.springs.push(new Spring(vertices, getVertexIndex(x, y), getVertexIndex(x + 1, y + 1))); + newFace.springs.push(new Spring(vertices, getVertexIndex(x + 1, y), getVertexIndex(x, y + 1))); + newFace.springs.push(new Spring(vertices, getVertexIndex(x + 1, y), getVertexIndex(x + 1, y + 1))); + newFace.springs.push(new Spring(vertices, getVertexIndex(x, y + 1), getVertexIndex(x + 1, y + 1))); + + faces.push(newFace); + } + } + + /** + * call createExplicit + * with generated vertices and faces + */ + this.createExplicit(vertices, faces); + } + + /** + * Generate THREE JS Geometry + * (list of vertices and list of indices representing triangles) + * and calculate the weight of each face and split it between + * surrounding vertices + * @param {Array of Vector3} vertices + * @param {Array of Face} faces + */ + createExplicit(vertices, faces) { + /** + * Copy vertices and initialize vertex weights to 0 + */ + for (let i in vertices) { + this.geometry.vertices.push(vertices[i]); + this.vertexWeights.push(0); + } + /** + * copy faces, + * generate two triangles per face, + * calculate weight of face as its area + * and split between the 4 vertices + */ + for (let i in faces) { + let face = faces[i]; + + /** copy faces to class member */ + this.faces.push(face); + + /** generate triangles */ + this.geometry.faces.push(new THREE.Face3( + face.a, face.b, face.c + )); + this.geometry.faces.push(new THREE.Face3( + face.c, face.b, face.d + )); + + /** + * calculate area of face as combined area of + * its two composing triangles + */ + let xLength = vectorLength(this.geometry.vertices[face.b], this.geometry.vertices[face.a]); + let yLength = vectorLength(this.geometry.vertices[face.c], this.geometry.vertices[face.a]); + let weight = xLength * yLength / 2; + + xLength = vectorLength(this.geometry.vertices[face.b], this.geometry.vertices[face.d]); + yLength = vectorLength(this.geometry.vertices[face.c], this.geometry.vertices[face.d]); + weight += xLength * yLength / 2; + + /** + * split weight equally between four surrounding vertices + */ + this.vertexWeights[face.a] += weight / 4; + this.vertexWeights[face.b] += weight / 4; + this.vertexWeights[face.c] += weight / 4; + this.vertexWeights[face.d] += weight / 4; + } + + /** + * let THREE JS compute bounding sphere around generated mesh + * needed for View Frustum Culling internally + */ + this.geometry.computeBoundingSphere(); + } + + /** + * generate a debug mesh for visualizing + * vertices and springs of the cloth + * and add it to scene for rendering + * @param {Scene} scene - Scene to add Debug Mesh to + */ + createDebugMesh(scene) { + /** + * helper function to generate a single line + * between two Vertices with a given color + * @param {Vector3} from + * @param {Vector3} to + * @param {number} color + */ + function addLine(from, to, color) { + let geometry = new THREE.Geometry(); + geometry.vertices.push(from); + geometry.vertices.push(to); + let material = new THREE.LineBasicMaterial( { color: color, linewidth: 10 } ); + let line = new THREE.Line(geometry, material); + line.renderOrder = 1; + scene.add(line); + } + /** + * helper function to generate a small sphere + * at a given Vertex Position with color + * @param {Vector3} point + * @param {number} color + */ + function addPoint(point, color) { + const geometry = new THREE.SphereGeometry( 0.05, 32, 32 ); + const material = new THREE.MeshBasicMaterial( { color: color } ); + const sphere = new THREE.Mesh( geometry, material ); + sphere.position.set(point.x, point.y, point.z); + scene.add( sphere ); + } + + let lineColor = 0x000000; + let pointColor = 0xff00000; + + /** + * generate one line for each of the 6 springs + * and one point for each of the 4 vertices + * for all of the faces + */ + for (let i in this.faces) { + let face = this.faces[i]; + addLine(this.geometry.vertices[face.a], this.geometry.vertices[face.b], lineColor); + addLine(this.geometry.vertices[face.a], this.geometry.vertices[face.c], lineColor); + addLine(this.geometry.vertices[face.a], this.geometry.vertices[face.d], lineColor); + addLine(this.geometry.vertices[face.b], this.geometry.vertices[face.c], lineColor); + addLine(this.geometry.vertices[face.b], this.geometry.vertices[face.d], lineColor); + addLine(this.geometry.vertices[face.c], this.geometry.vertices[face.d], lineColor); + + addPoint(this.geometry.vertices[face.a], pointColor); + addPoint(this.geometry.vertices[face.b], pointColor); + addPoint(this.geometry.vertices[face.c], pointColor); + addPoint(this.geometry.vertices[face.d], pointColor); + } + } +} \ No newline at end of file -- 2.50.1