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diff --git a/frontend/rigidbody.html b/frontend/rigidbody.html new file mode 100644 index 0000000..510c667 --- /dev/null +++ b/frontend/rigidbody.html @@ -0,0 +1,152 @@ +<!DOCTYPE html> +<html lang="en"> + <head> + <meta charset="utf-8"> + <script src="scripts/jquery-3.5.1.min.js"></script> + <script src="index.js"></script> + <link rel="stylesheet" href="/../index.css"> + <link href="https://fonts.googleapis.com/css?family=Open+Sans:400,600,300" rel="stylesheet" type="text/css"> + <title>Simple Website</title> + + <script src="_rigidbody/vec2.js"></script> + <script src="_rigidbody/mat4.js"></script> + <script src="_rigidbody/shader.js"></script> + <script src="_rigidbody/circle.js"></script> + <script src="_rigidbody/program_common.js"></script> + <script src="_rigidbody/rigidbody_1.js"></script> + <script src="_rigidbody/rigidbody_2.js"></script> + </head> + <body> + <header> + <h1>Matt Kae's Programming Blog</h1> + </header> + <nav> + <a href="/">Home</a> + <a href="rigidbody.html">Rigid Body</a> + <a href="references.html">Books n' References</a> + </nav> + <main> + <section> + <p> + <ul> + <li><a href="#introduction">Introduction</a></li> + <li><a href="#linear-forces">Part 1: Linear Forces</a></li> + <li><a href="#rotational-forces">Part 2: Rotational Forces</a></li> + </ul> + </p> + </section> + <section id='introduction'> + <h2>Introduction: Rigid Body Physics</h2> + <p> + You're most likely here because you have some interest in the world of rigid body physics. Maybe you have some knowledge of rendering via OpenGL or Vulkan, + and you want to begin watching your up-until-now static scene come to life. Well, you're in the right place! In the course of this tutorial series I will walk + you through the entirety of a 2D rigid body physics system entirely in the web. All of this information will be extendable to other languages, but we will use + JavaScript and WebGL in these blog posts. Additionally, much of the information presented here can be extended to 3 dimensions, but 3D carries some complications + with it, that we will discuss in future blog posts. + </p> + <p> + In implementing a rigidy body physics system, we're primarily interested in two sub-fields of physics, namely <b>dynamics</b> and <b>kinematics</b>. Although I'm + far as can be from being an expert in either of these fields, I will explain - from a programmer's persepctive - what they mean to me: + <ul> + <li> + <b>Kinematics</b> is the study of how an object's movement changes over time. These are the classic position, velocity, and acceleration equations + that you're most likely familiar with from high school or college physics. + </li> + <li> + <b>Dynamics</b> is the study of whats <i>causes</i> kinematic movement. These are the classic force and momentum equations that you may already be familiar + with as well. + </li> + </ul> + </p> + <p> + Finally, I must provide a disclaimer that all of rigid body systems are very math-y. You will need to know a decent amount of vector calculus and linear algebra to really understand + what's going on here. I am going to assume that you have this knowledge. If you don't already have this knowledge, I will try and provide some resources on the Books + n' References page of the website. + </p> + </section> + <hr /> + <section id="linear-forces"> + <h2>Part 1: Linear Forces</h2> + <p> + The first - and perhaps easiest - part of implementing any rigid body physics system is getting the entities in your scene to move in response to linear forces. + With this implementation alone, you can achieve an interesting level of realism in your 2D (and even 3D) scene. + </p> + <p> + Let's begin by recalling the relationships between acceleration, velocity, and position. + </p> + <p> + Knowing all this, you should be able to understand the following source code fairly easily; + <pre> + <code> +<span class="code_keyword">function</span> update(dtSeconds) { + <span class="code_comment">// Add up the forces acting on the circle</span> + <span class="code_keyword">const</span> GRAVITY = 9.8; + <span class="code_keyword">const</span> lGravityForce = vec2(0, -1.0 * (lCircle.mass * <span class="code_constant">GRAVITY</span>)); + lCircle.force = addVec2(lCircle.force, lGravityForce); + + <span class="code_comment">// Figure out acceleration (a = F / m)</span> + <span class="code_keyword">const</span> lCurrentAcceleration = scaleVec2(lCircle.force, 1.0 / lCircle.mass); + + <span class="code_comment">// Calculate the new velocity: v = v0 + a * t</span> + lCircle.velocity = addVec2(lCircle.velocity, scaleVec2(lCurrentAcceleration, dtSeconds)); + + <span class="code_comment">// Update the position based on velocity: x = x0 + v * t</span> + lCircle.position = addVec2(lCircle.position, scaleVec2(lCircle.velocity, dtSeconds)); + + <span class="code_comment">// Update the model matrix accordingly</span> + lCircle.model = translateMatrix(mat4(), lCircle.position.x, lCircle.position.y, 0); + + <span class="code_comment">// Reset the force vector for the next update</span> + lCircle.force = vec2() +} + </code> + </pre> + </p> + <div id="rigidbody_1" class="opengl_canvas_container"> + <canvas width="640" height="480"></canvas> + <div class="opengl_canvas_sidebar"> + <ul class="opengl_value_tracker"> + <li><b>Force:</b><span id="rigidbody_1_force_field">N/A</span></li> + <li><b>Acceleration:</b><span id="rigidbody_1_acceleration_field">N/A</span></li> + <li><b>Velocity:</b><span id="rigidbody_1_velocity_field">N/A</span></li> + <li><b>Position:</b><span id="rigidbody_1_position_field">N/A</span></li> + </ul> + <form id="rigidbody_1_force_submit_button" style="text-align: right; padding: 0.5rem;"> + <div class="vec2_input_group"> + <input class="vec2_x_input" type="number" value="0"/> + <input class="vec2_y_input" type="number" value="5000"/> + </div> + <input type="submit" value="Apply Force"></input> + </form> + </div> + <button class="play_button"> + Play + </button> + <button class="stop_button"> + Stop + </button> + </div> + </section> + <hr /> + <section id="rotational-forces"> + <h2>Part 2: Rotational Forces</h2> + <p> + </p> + <div id="rigidbody_2" class="opengl_canvas_container"> + <canvas width="640" height="480"></canvas> + <div class="opengl_canvas_sidebar"> + + </div> + <button class="play_button"> + Play + </button> + <button class="stop_button"> + Stop + </button> + </div> + </section> + + <section style="height: 50vh;"></section> + </main> + </body> +</html>
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