Pendulum: Shit's fucked
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@ -17,6 +17,7 @@
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<script src="../lib/webgl-debug.js"></script>
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<script src="../lib/cuon-utils.js"></script>
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<script src="../lib/cuon-matrix.js"></script>
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<script src="PendulumComponents.js"></script>
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<script src="Pendulum.js"></script>
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</body>
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</html>
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@ -1,4 +1,9 @@
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// RotatingTranslatedTriangle.js (c) 2012 matsuda
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// Pendulum.js
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// John Breaux 2022-06-30
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// Simulates a pendulum in a frictionless vacuum with no gravity
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"use strict"
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const vertex_shader = `
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@ -8,6 +13,7 @@ const vertex_shader = `
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void main()
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{
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gl_Position = u_ModelMatrix * a_Position;
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gl_PointSize = 5.0;
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} `;
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@ -26,92 +32,16 @@ var PEN_LENGTH = 0.8;
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// Rotation angle (degrees/second)
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var A_VELOCITY = 45.0;
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// Classes
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// homo2: Stores a 2d vector or point in homog. coords
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class homog2 {
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constructor(x = 0, y = 0, w = 0) {
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this.x = x;
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this.y = y;
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this.w = w;
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}
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// Add with modify
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add_m(rhs) {
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if (rhs) {
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this.x += rhs.x;
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this.y += rhs.y;
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this.w += rhs.w;
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return this;
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}
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else return null;
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}
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// scalar multiply with modify
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smul_m(scalar) {
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if (typeof(rhs) === "number") {
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this.x *= rhs;
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this.y *= rhs;
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this.w *= rhs;
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return this;
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}
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else return null;
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}
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// copy
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copy() {
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return new homog2(this.x, this.y, this.w);
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}
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// create vector/point from 2d polar coordinates
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from_polar(r = 0, theta = 0, w = 0) {
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this.x = r * Math.cos(theta);
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this.y = r * Math.sin(theta);
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this.w = w;
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return this;
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}
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}
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// hexagon2 class: Holds 6 vertices and a center point. Only constructs perfect hexagons.
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class hexagon2 {
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// constructor: Make a new regular polygon
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constructor({sides = 6, radius = 0, rotation = 0, center = { x: 0, y: 0 } } = {}) {
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// lenth is center + sides
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this.length = 1;
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this.center = new homog2(center.x, center.y, 1);
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this.v = [];
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for (var i = 0; i <= sides; i++) {
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this.v[i] = new homog2().from_polar(radius, rotation + (i*2*Math.PI / sides)).add_m(this.center);
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this.length++;
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}
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}
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// Convert to Float32Array [center, v0, v1, ...]
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to_array() {
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// allocate space for center.xy + vertices.xy
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var ret = new Float32Array((1 + this.v.length) * 2);
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// save the center
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ret[0] = this.center.x;
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ret[1] = this.center.y;
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// save the vertices
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for (var i = 0; i < this.v.length; i++) {
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var j = 2 * (i + 1);
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ret[j] = this.v[i].x;
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ret[j+1] = this.v[i].y;
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}
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return ret;
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}
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draw(gl, n, currentAngle, modelMatrix, u_ModelMatrix) {
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// Set the rotation matrix
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modelMatrix.setRotate(currentAngle, 0, 0, 1);
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// Pass the rotation matrix to the vertex shader
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gl.uniformMatrix4fv(u_ModelMatrix, false, modelMatrix.elements);
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// Clear <canvas>
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gl.clear(gl.COLOR_BUFFER_BIT);
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// Draw the pendulum
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gl.drawArrays(gl.TRIANGLE_FAN, 0, n);
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}
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}
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class pendulum2 {
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constructor({angle = 0, length = PEN_LENGTH, radius = BOB_RADIUS} = {}) {
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this.bob = new hexagon2({radius: radius, center: {x: 0, y: -length}});
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console.log(this);
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// Common functions:
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// acquire_buffer: Get a vertex buffer object from gl
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function acquire_buffer(gl) {
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// Create a buffer object
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var vertexBuffer = gl.createBuffer();
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if (!vertexBuffer) {
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console.log('Failed to create the buffer object');
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return -1;
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}
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return vertexBuffer;
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}
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function main() {
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@ -132,14 +62,8 @@ function main() {
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}
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// create a pendulum object
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var pendulum = new pendulum2({angle: 0, length: 0});
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// Write the positions of vertices to a vertex shader
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var n = initVertexBuffers(gl, pendulum);
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if (n < 0) {
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console.log('Failed to set the positions of the vertices');
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return;
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}
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var pendulum = new Pendulum({ angle: 0, length: PEN_LENGTH, radius: BOB_RADIUS });
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init(gl, pendulum);
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// Specify the color for clearing <canvas>
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gl.clearColor(0, 0, 0, 1);
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@ -151,81 +75,32 @@ function main() {
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return;
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}
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// Current rotation angle
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var currentAngle = 0.0;
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// Model matrix
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var modelMatrix = new Matrix4();
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// Set it to the I matrix
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modelMatrix.setIdentity();
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// Start drawing
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var tick = function () {
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currentAngle = animate(currentAngle); // Update the rotation angle
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pendulum.bob.draw(gl, n, currentAngle, modelMatrix, u_ModelMatrix); // Draw the triangle
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requestAnimationFrame(tick, canvas); // Request that the browser ?calls tick
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// Tick the pendulum
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pendulum.tick();
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// Draw the pendulum
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draw(gl, pendulum, modelMatrix, u_ModelMatrix);
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// Request that the browser ?calls tick
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requestAnimationFrame(tick, canvas);
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};
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tick();
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}
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function initVertexBuffers(gl, pendulum) {
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// var vertices = new Float32Array([
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// 0, 0.5, -0.5, -0.5, 0.5, -0.5
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// ]);
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// var n = 3; // The number of vertices
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var vertices = pendulum.bob.to_array();
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var n = pendulum.bob.length;
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// Create a buffer object
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var vertexBuffer = gl.createBuffer();
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if (!vertexBuffer) {
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console.log('Failed to create the buffer object');
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return -1;
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}
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// Bind the buffer object to target
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gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
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// Write date into the buffer object
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gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
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// Assign the buffer object to a_Position variable
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var a_Position = gl.getAttribLocation(gl.program, 'a_Position');
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if (a_Position < 0) {
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console.log('Failed to get the storage location of a_Position');
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return -1;
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}
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gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);
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// Enable the assignment to a_Position variable
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gl.enableVertexAttribArray(a_Position);
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return n;
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function init(gl, pendulum) {
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pendulum.init(gl);
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}
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function draw(gl, n, currentAngle, modelMatrix, u_ModelMatrix) {
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// Set the rotation matrix
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modelMatrix.setRotate(currentAngle, 0, 0, 1);
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modelMatrix.translate(0.35, 0, 0);
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// Pass the rotation matrix to the vertex shader
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gl.uniformMatrix4fv(u_ModelMatrix, false, modelMatrix.elements);
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function draw(gl, pendulum, modelMatrix, u_ModelMatrix) {
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// Clear <canvas>
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gl.clear(gl.COLOR_BUFFER_BIT);
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// Draw the rectangle
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gl.drawArrays(gl.TRIANGLES, 0, n);
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}
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// Last time that this function was called
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var g_last = Date.now();
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function animate(angle) {
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// Calculate the elapsed time
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var now = Date.now();
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var elapsed = now - g_last;
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g_last = now;
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// Update the current rotation angle (adjusted by the elapsed time)
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var newAngle = angle + (A_VELOCITY * elapsed) / 1000.0;
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return newAngle %= 360;
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// Draw the pendulum
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pendulum.draw(gl, modelMatrix, u_ModelMatrix);
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}
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function up() {
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210
Pendulum/PendulumComponents.js
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210
Pendulum/PendulumComponents.js
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@ -0,0 +1,210 @@
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// PendulumComponents.js
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// John Breaux 2022-06-30
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// Classes and data structures for Pendulum.js
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"use strict"
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// Classes
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// homo2: Stores a 2d vector or point in homog. coords
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class homog2 {
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constructor(x = 0, y = 0, w = 0) {
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this.x = x;
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this.y = y;
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this.w = w;
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}
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// Add with modify
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add_m(rhs) {
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if (rhs) {
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this.x += rhs.x;
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this.y += rhs.y;
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this.w += rhs.w;
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return this;
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}
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else return null;
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}
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// scalar multiply with modify
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smul_m(scalar) {
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if (typeof (rhs) === "number") {
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this.x *= rhs;
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this.y *= rhs;
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this.w *= rhs;
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return this;
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}
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else return null;
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}
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// copy
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copy() {
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return new homog2(this.x, this.y, this.w);
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}
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// create vector/point from 2d polar coordinates
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from_polar(r = 0, theta = 0, w = 0) {
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this.x = r * Math.cos(theta);
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this.y = r * Math.sin(theta);
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this.w = w;
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return this;
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}
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}
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class Anchor {
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constructor({ center = { x: 0, y: 0 } } = {}) {
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this.position = new homog2(center.x, center.y, 1);
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}
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// Convert to Float32Array [center, v0, v1, ...]
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vertex_array() {
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// allocate space for center.xy + vertices.xy
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var ret = new Float32Array(2);
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// save the vertices
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ret[0] = this.position.x, ret[1] = this.position.y;
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console.log(ret);
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return ret;
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}
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// Generate the index_array for the shape
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index_array() {
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var ret = new Uint8Array(1);
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ret[0] = 0;
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console.log(ret);
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return ret;
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}
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init(gl) {
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// Make the buffers
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this.vertexBuffer = acquire_buffer(gl);
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this.indexBuffer = acquire_buffer(gl);
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// Bind the buffers
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gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
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gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.indexBuffer);
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// Acquire a reference to a_Position
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var a_Position = gl.getAttribLocation(gl.program, 'a_Position');
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if (a_Position < 0) {
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console.log('Failed to get the storage location of a_Position');
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return -1;
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}
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gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);
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// Enable the assignment to a_Position variable
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gl.enableVertexAttribArray(a_Position);
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// Write date into the buffers
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gl.bufferData(gl.ARRAY_BUFFER, this.vertex_array(), gl.STATIC_DRAW);
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gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, this.index_array(), gl.STATIC_DRAW);
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}
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draw(gl, modelMatrix, u_ModelMatrix) {
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// Bind the buffers
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gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
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gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.indexBuffer);
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// Pass the rotation matrix to the vertex shader
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gl.uniformMatrix4fv(u_ModelMatrix, false, modelMatrix.elements);
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// Draw the Anchor
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gl.drawElements(gl.POINTS, 1, gl.UNSIGNED_BYTE, 0);
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}
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}
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// hexagon2 class: Holds vertices and a center point. Only constructs regular polygons
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class Polygon {
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// constructor: Make a new regular polygon
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constructor({ sides = 6, radius = 1, rotation = 0, center = { x: 0, y: 0 }, color = { r: 0, g: 0, b: 1 } } = {}) {
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this.length = 0;
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// vertices
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this.vertices = [];
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this.center = new homog2(center.x, center.y, 1);
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for (var i = 0; i <= sides; i++) {
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this.vertices[i] = new homog2().from_polar(radius, rotation + (i * 2 * Math.PI / sides)).add_m(this.center);
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this.length++;
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}
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}
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// Convert to Float32Array [center, v0, v1, ...]
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vertex_array() {
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// allocate space for center.xy + vertices.xy
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var ret = new Float32Array((this.vertices.length) * 2);
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// save the vertices
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for (var i = 0; i < this.vertices.length; i++) {
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var j = 2 * i;
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ret[j] = this.vertices[i].x;
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ret[j + 1] = this.vertices[i].y;
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}
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return ret;
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}
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// Generate the index_array for the shape
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index_array() {
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var ret = new Uint8Array(this.vertices.length + 1);
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for (var i = 0; i < this.vertices.length; i++) {
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ret[i] = i
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}
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ret[this.vertices.length] = 0;
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return ret;
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}
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init(gl) {
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// Make the buffers
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this.vertexBuffer = acquire_buffer(gl);
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this.indexBuffer = acquire_buffer(gl);
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// Bind the buffers
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gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
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gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.indexBuffer);
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// Acquire a reference to a_Position
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var a_Position = gl.getAttribLocation(gl.program, 'a_Position');
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if (a_Position < 0) {
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console.log('Failed to get the storage location of a_Position');
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return -1;
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}
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gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);
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// Enable the assignment to a_Position variable
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gl.enableVertexAttribArray(a_Position);
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// Write date into the buffers
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gl.bufferData(gl.ARRAY_BUFFER, this.vertex_array(), gl.STATIC_DRAW);
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gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, this.index_array(), gl.STATIC_DRAW);
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}
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draw(gl, modelMatrix, u_ModelMatrix) {
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gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
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gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.indexBuffer);
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// Pass the rotation matrix to the vertex shader
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gl.uniformMatrix4fv(u_ModelMatrix, false, modelMatrix.elements);
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// Draw the shape
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gl.drawElements(gl.TRIANGLE_FAN, this.length, gl.UNSIGNED_BYTE, 0);
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}
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}
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class Pendulum {
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constructor({ angle = 0, length = PEN_LENGTH, radius = BOB_RADIUS, anchor = { x: 0, y: 0 } } = {}) {
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this.angle = angle;
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this.components = [
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new Anchor({ center: anchor }),
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new Polygon({ radius: radius, center: { x: 0, y: -length } })
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];
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}
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// Tick the pendulum (update and perform movement)
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tick() {
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var now = Date.now(), elapsed = now - this.t_prev;
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this.t_prev = now;
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this.angle = (this.angle + (A_VELOCITY * elapsed / 1000)) % 360;
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}
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// Initialize the pendulum
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init(gl) {
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// initialize the components
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for(var component of this.components) {
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component?.init(gl);
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}
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// start the clock
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this.t_prev = Date.now();
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}
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// Draw the pendulum
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draw(gl, modelMatrix, u_ModelMatrix) {
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// Rotate the pendulum
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modelMatrix.setRotate(this.angle, 0, 0, 1);
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// Draw each component
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for (var component of this.components) {
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component?.draw(gl, modelMatrix, u_ModelMatrix);
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}
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}
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}
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