X-Git-Url: https://gitweb.ps.run/cloth_sim/blobdiff_plain/c2adddfd9ecca5d483cf3147b8bd4870f3ea6150..f3d7f6c46c59cd98eb64a079301b872ca2a6a2f3:/Scripts/main.js?ds=sidebyside diff --git a/Scripts/main.js b/Scripts/main.js index f395b6c..4d7ac7c 100644 --- a/Scripts/main.js +++ b/Scripts/main.js @@ -1,55 +1,370 @@ -function init() { - class Point { - constructor(x, y) { - this.x = x; - this.y = y; +class Point { + constructor(x, y) { + this.x = x; + this.y = y; + } + + add(that) { + return new Point( + this.x + that.x, + this.y + that.y + ); + } + + sub(that) { + return new Point( + this.x - that.x, + this.y - that.y + ); + } + + dist(that) { + let a = this.x - that.x; + let b = this.y - that.y; + return Math.sqrt(a * a + b * b) + } +} + +/** + * 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 + */ +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 + */ +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 + */ +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) + ); + } } - add(that) { - return new Point( - this.x + that.x, - this.y + that.y - ); + /** + * 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), + ); - sub(that) { - return new Point( - this.x - that.x, - this.y - that.y - ); + 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); + } } - dist(that) { - let a = this.x - that.x; - let b = this.y - that.y; - return Math.sqrt(a * a + b * b) + /** + * 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(); } - let mousePos = new Point(); + /** + * 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 ); + } - const scene = new THREE.Scene(); - const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000); + 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); + } + } +} + +/** + * setup THREE JS Scene, Camera and Renderer + */ +function setup_scene() { + const scene = new THREE.Scene(); + const camera = new THREE.PerspectiveCamera(75, window.innerWidth / (window.innerHeight - canvasSpace), 0.1, 1000); const renderer = new THREE.WebGLRenderer(); - renderer.setSize(window.innerWidth, window.innerHeight - 200); + /** size canvas to leave some space for UI */ + renderer.setSize(window.innerWidth, window.innerHeight - canvasSpace); + /** embed canvas in HTML */ document.getElementById("threejscontainer").appendChild(renderer.domElement); + /** add global light */ const directionalLight = new THREE.DirectionalLight(0xffffff, 1); scene.add(directionalLight); - const geometry = new THREE.BoxGeometry(); - const material = new THREE.MeshBasicMaterial({ color: 0x00ff00 }); - const cube = new THREE.Mesh(geometry, material); - scene.add(cube); + /** position camera */ + camera.position.y = 5; + camera.position.z = 10; + + return [scene, camera]; +} + +function init() { + let mousePos = new Point(); + + /** + * Space left empty under canvas + * for UI elements + */ + const canvasSpace = 200; - camera.position.z = 5; + /** Setup scene */ + let [scene, camera] = setup_scene(); + + /** setup cloth and generate debug mesh */ + let cloth = new Cloth(); + cloth.createBasic(10, 10, 5, 5); + cloth.createDebugMesh(scene); + const material = new THREE.MeshBasicMaterial({ color: 0x0000ff }); + const mesh = new THREE.Mesh(cloth.geometry, material); + scene.add(mesh); + + /** + * function called every frame + * @param {number} dt - time passed since last frame + */ function animate(dt) { requestAnimationFrame(animate); renderer.render(scene, camera); } + /** add callback for window resize */ let canvas = document.getElementsByTagName("canvas")[0]; let resize = function () { w = window.innerWidth; @@ -59,10 +374,16 @@ function init() { } window.onresize = resize; resize(); + + /** + * if canvas has been successfully initialized + * start rendering + */ if (canvas.getContext) { - ctx = canvas.getContext('2d'); animate(performance.now()); } + + /** add mouse move callback */ canvas.onmousemove = (evt) => { mousePos.x = evt.clientX; mousePos.y = evt.clientY;