From 3b4b277871c37aa0980e3dd6cc650c781c8a61d6 Mon Sep 17 00:00:00 2001 From: John Breaux Date: Thu, 30 Jun 2022 16:10:19 -0500 Subject: [PATCH] Pendulum: Create a class for regular polygon --- Pendulum/Pendulum.js | 168 ++++++++++++++++++++++++++++++++----------- 1 file changed, 128 insertions(+), 40 deletions(-) diff --git a/Pendulum/Pendulum.js b/Pendulum/Pendulum.js index 627d111..f541e75 100644 --- a/Pendulum/Pendulum.js +++ b/Pendulum/Pendulum.js @@ -1,26 +1,120 @@ // RotatingTranslatedTriangle.js (c) 2012 matsuda +"use strict" const vertex_shader = ` attribute vec4 a_Position; uniform mat4 u_ModelMatrix; - - void main() + + void main() { gl_Position = u_ModelMatrix * a_Position; } `; const fragment_shader = ` - void main() + void main() { gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0); } `; +// Point size of the anchor +var POINT_SIZE = 5; +// Radius of the bob +var BOB_RADIUS = 0.1; +// length of the wire +var PEN_LENGTH = 0.8; // Rotation angle (degrees/second) -var ANGLE_STEP = 45.0; +var A_VELOCITY = 45.0; -function main() -{ +// Classes +// homo2: Stores a 2d vector or point in homog. coords +class homog2 { + constructor(x = 0, y = 0, w = 0) { + this.x = x; + this.y = y; + this.w = w; + } + // Add with modify + add_m(rhs) { + if (rhs) { + this.x += rhs.x; + this.y += rhs.y; + this.w += rhs.w; + return this; + } + else return null; + } + // scalar multiply with modify + smul_m(scalar) { + if (typeof(rhs) === "number") { + this.x *= rhs; + this.y *= rhs; + this.w *= rhs; + return this; + } + else return null; + } + // copy + copy() { + return new homog2(this.x, this.y, this.w); + } + // create vector/point from 2d polar coordinates + from_polar(r = 0, theta = 0, w = 0) { + this.x = r * Math.cos(theta); + this.y = r * Math.sin(theta); + this.w = w; + return this; + } +} + +// hexagon2 class: Holds 6 vertices and a center point. Only constructs perfect hexagons. +class hexagon2 { + // constructor: Make a new regular polygon + constructor({sides = 6, radius = 0, rotation = 0, center = { x: 0, y: 0 } } = {}) { + // lenth is center + sides + this.length = 1; + this.center = new homog2(center.x, center.y, 1); + this.v = []; + for (var i = 0; i <= sides; i++) { + this.v[i] = new homog2().from_polar(radius, rotation + (i*2*Math.PI / sides)).add_m(this.center); + this.length++; + } + } + // Convert to Float32Array [center, v0, v1, ...] + to_array() { + // allocate space for center.xy + vertices.xy + var ret = new Float32Array((1 + this.v.length) * 2); + // save the center + ret[0] = this.center.x; + ret[1] = this.center.y; + // save the vertices + for (var i = 0; i < this.v.length; i++) { + var j = 2 * (i + 1); + ret[j] = this.v[i].x; + ret[j+1] = this.v[i].y; + } + return ret; + } + draw(gl, n, currentAngle, modelMatrix, u_ModelMatrix) { + // Set the rotation matrix + modelMatrix.setRotate(currentAngle, 0, 0, 1); + // Pass the rotation matrix to the vertex shader + gl.uniformMatrix4fv(u_ModelMatrix, false, modelMatrix.elements); + // Clear + gl.clear(gl.COLOR_BUFFER_BIT); + // Draw the pendulum + gl.drawArrays(gl.TRIANGLE_FAN, 0, n); + } +} + +class pendulum2 { + constructor({angle = 0, length = PEN_LENGTH, radius = BOB_RADIUS} = {}) { + this.bob = new hexagon2({radius: radius, center: {x: 0, y: -length}}); + console.log(this); + } +} + +function main() { // Retrieve element var canvas = document.getElementById('webgl'); @@ -32,16 +126,17 @@ function main() } // Initialize shaders - if (!initShaders(gl, vertex_shader, fragment_shader)) - { + if (!initShaders(gl, vertex_shader, fragment_shader)) { console.log('Failed to intialize shaders.'); return; } + // create a pendulum object + var pendulum = new pendulum2({angle: 0, length: 0}); + // Write the positions of vertices to a vertex shader - var n = initVertexBuffers(gl); - if (n < 0) - { + var n = initVertexBuffers(gl, pendulum); + if (n < 0) { console.log('Failed to set the positions of the vertices'); return; } @@ -51,53 +146,50 @@ function main() // Get storage location of u_ModelMatrix var u_ModelMatrix = gl.getUniformLocation(gl.program, 'u_ModelMatrix'); - if (!u_ModelMatrix) - { + if (!u_ModelMatrix) { console.log('Failed to get the storage location of u_ModelMatrix'); return; } // Current rotation angle var currentAngle = 0.0; - + // Model matrix var modelMatrix = new Matrix4(); // Start drawing - var tick = function() - { + var tick = function () { currentAngle = animate(currentAngle); // Update the rotation angle - draw(gl, n, currentAngle, modelMatrix, u_ModelMatrix); // Draw the triangle + pendulum.bob.draw(gl, n, currentAngle, modelMatrix, u_ModelMatrix); // Draw the triangle requestAnimationFrame(tick, canvas); // Request that the browser ?calls tick }; tick(); } -function initVertexBuffers(gl) -{ - var vertices = new Float32Array ([ - 0, 0.5, -0.5, -0.5, 0.5, -0.5 - ]); - var n = 3; // The number of vertices +function initVertexBuffers(gl, pendulum) { + // var vertices = new Float32Array([ + // 0, 0.5, -0.5, -0.5, 0.5, -0.5 + // ]); + // var n = 3; // The number of vertices + var vertices = pendulum.bob.to_array(); + var n = pendulum.bob.length; // Create a buffer object var vertexBuffer = gl.createBuffer(); - if (!vertexBuffer) - { + if (!vertexBuffer) { console.log('Failed to create the buffer object'); return -1; } // Bind the buffer object to target gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer); - + // Write date into the buffer object gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW); // Assign the buffer object to a_Position variable var a_Position = gl.getAttribLocation(gl.program, 'a_Position'); - if(a_Position < 0) - { + if (a_Position < 0) { console.log('Failed to get the storage location of a_Position'); return -1; } @@ -109,12 +201,11 @@ function initVertexBuffers(gl) return n; } -function draw(gl, n, currentAngle, modelMatrix, u_ModelMatrix) -{ +function draw(gl, n, currentAngle, modelMatrix, u_ModelMatrix) { // Set the rotation matrix modelMatrix.setRotate(currentAngle, 0, 0, 1); modelMatrix.translate(0.35, 0, 0); - + // Pass the rotation matrix to the vertex shader gl.uniformMatrix4fv(u_ModelMatrix, false, modelMatrix.elements); @@ -127,23 +218,20 @@ function draw(gl, n, currentAngle, modelMatrix, u_ModelMatrix) // Last time that this function was called var g_last = Date.now(); -function animate(angle) -{ +function animate(angle) { // Calculate the elapsed time var now = Date.now(); var elapsed = now - g_last; g_last = now; // Update the current rotation angle (adjusted by the elapsed time) - var newAngle = angle + (ANGLE_STEP * elapsed) / 1000.0; + var newAngle = angle + (A_VELOCITY * elapsed) / 1000.0; return newAngle %= 360; } -function up() -{ - ANGLE_STEP += 10; +function up() { + A_VELOCITY += 10; } -function down() -{ - ANGLE_STEP -= 10; +function down() { + A_VELOCITY -= 10; }