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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<link rel="stylesheet" href="/index.css">
<title>Physics for Games</title>
<link rel="shortcut icon" href="/favicon/favicon.ico" type="image/x-icon">
<meta name="description" content="A place to learn all about real-time physics simulations through descriptions, code snippets, and example programs all written in C++ and OpenGL.">
<meta name="og:description" content="A place to learn all about real-time physics simulations through descriptions, code snippets, and example programs all written in C++ and OpenGL.">
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<body>
<header>
<h1><a title="physicsforgames.com" href="/">Physics for Games</a></h1>
</header>
<main>
<nav>
<ul class="outer-tree">
<li><a href="/">Introduction</a></li>
<li>
<span>🏀<span>2D</span></span>
<ul class="inner-tree">
<li><label>Rigidbody</label></li>
<li><a title="/2d/rigidbody/rigidbody_1.html" href="/2d/rigidbody/rigidbody_1.html">Linear Forces</a></li>
<li><a title="/2d/rigidbody/rigidbody_2.html" href="/2d/rigidbody/rigidbody_2.html">Rotational Forces</a></li>
<li><a title="/2d/rigidbody/rigidbody_3.html" href="/2d/rigidbody/rigidbody_3.html">Collisions</a></li>
<li><label>Collisions</label></li>
<li><a title="/2d/_collisions/rectangle_line.html" href="/2d/_collisions/rectangle_line.html">Rectangle-Line</a></li>
<li><a title="/2d/_collisions/rectangle_rectangle.html" href="/2d/_collisions/rectangle_rectangle.html">Rectangle-Rectangle</a></li>
<li><a title="/2d/_collisions/polygon_polygon.html" href="/2d/_collisions/polygon_polygon.html">Separating Axis Theorem</a></li>
</ul>
</li>
<li>
<span>🌠<span>3D</span></span>
<ul class="inner-tree">
<li><label>Rigidbody</label></li>
<li><a title="/3d/rigidbody.html" href="/3d/rigidbody.html">Rigidbody in 3D</a></li>
</ul>
</li>
<li>
<span>🔧<span>WebAssembly</span></span>
<ul class="inner-tree">
<li><a title="/intro/intro.html" href="/intro/intro.html">Introduction</a></li>
</ul>
</li>
<li>
<span>🛈<span>About</span></span>
<ul class="inner-tree">
<li><a title="/roadmap.html" href="/roadmap.html">Roadmap</a></li>
</ul>
</li>
</ul>
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<style>
section ul {
list-style: none;
padding-left: 0;
}
section li {
position: relative;
padding-left: 1.5em; /* space to preserve indentation on wrap */
}
section li:before {
content: '';
position: absolute;
left: 0;
width: 1rem;
height: 1rem;
}
section ul {
list-style: none;
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section ul li:before {
content: '-';
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.abandoned {
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section ul li.failed:before {
content: '✗'
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</style>
<article>
<section>
<h1>July 2021: 2D loose ends and 3D headway</h1>
<ul>
<li class="halfway">Finish SAT Collision Info (very close)</li>
<li class="halfway">2D rigidbody explanation 3</li>
<li>3D Rigid Body Collisions</li>
<li>ZIP file creator for downloads</li>
<li>Explanation of Quaternions</li>
</ul>
<p>
The last two months went almost as planned. I think I misjudged how long and how much brainpower it would
take me to write explanations for all of these things. A classic engineer mistake. We see writing,
and we think, "Easy, I can do that." And I usually can, but I am a bit rusty as of late. Additionally, this
writing involved a lot of diagrams and math equations that I struggled to put into HTML. I even had to learn
to make some simple drawings in gimp, which was a bit of a hurdle.
<br /><br />
That being said, I am fairly configdent that I can finish the above items in the month of July (maybe minus the
quaternion work, but we will see). To get my confidence up, I am going to begin with the ZIP file creator for
downloading individual projects. That will definitely be worthwhile.
</p>
</section>
<section>
<h1>May/June 2021: More Collisions</h1>
<ul>
<li class="halfway">SAT Collisions for Convex Polygons with Explanation</li>
<li class="done">2D rigidbody physics demo + explanation 1</li>
<li class="done">2D rigidbody physics demo + explanation 2</li>
<li class="halfway">2D rigidbody physics demo + explanation 3</li>
<li class="done">Remove (or hide) ellipse collision pages for now</li>
<li class="done">3D scene setup</li>
<li class="abandoned">3D scene basic physics with spheres bouncing around a scene</li>
<li class="abandoned">Pill Collisions</li>
</ul>
<p style="font-size: 18px;">
Obviously, the month of April did not go as planned. I got caught up with a number of tasks that I couldn't handle,
namely, the pill collisions. These, as I discovered, were quite unfeasible and involved a lot of complex maths
that I didn't quite yet understand. They are also unreasonable for game development's sake, so I will ditch that
effort and focus on doing other things. This, of course, is not time entirely wasted, as I now I have a somewhat
better understanding of why ellipses (and by extension ellipsoids, although I am not entirely sure of this). I should
<i>instead</i> try to figure out the intersection using pills, not ellipses. Pills are simply 2D shapes made of a
rectangle in the middle and two half-circles at either ends. This is a far less expensive collision to calculate.
<br/><br/>
I also failed when it came to getting a good physics collision system going. This stemmed from a general misunderstanding
of moment of inertia and how it can properly be implemented for each shape. I think I am getting a better grip on it now,
however.
<br/><br/>
And that brings me to May/June. I am combining these two months because I am quite busy in May with family stuff,
and hence won't be able to give my full attention to the project. That being said, as a high-level goal, I hope to
get some more 2D collisions going, and maybe move onto 3D fairly soon. For 3D, I would simply like to get the physics
simulation up and running with simple objects (spheres, cubes, etc.). From there, I want to begin exploring more complex
physics simulation topics like oct-trees, multiple collision resolution, etc. We will see what happens, but I am optimistic,
so long as I stay the course.
<br/><br/>
<i>Edit:</i> I am going to focus on SAT collision and AABB collision detection going forward for this month. In addition,
I am going to finish the descriptions/demos for regular rigidbody collision. Afterwards, if I have time, I will move onto
3D collisions.
</p>
</section>
<hr/>
<section>
<h1>April 2021: Ground Work and Initial Collisions</h1>
<ul>
<li class="done">Orthographic rendering basics</li>
<li class="done">Uniform build Process for WebAssembly</li>
<li class="done">WASM Framework with simulation loop</li>
</ul>
<h2>2D Collisions with Descriptions</h1>
<ul>
<li class="halfway">Ellipse-Line Collision</li>
<li class="failed">Ellipse-Ellipse Collisions</li>
<li class="failed">Ellipse-Circle Collisions</li>
<li class="failed">Ellipse-Square Collisions</li>
<li class="done">Rectangle-Line Collisions</li>
<li class="halfway">Circle-Line Collisions (Redo)</li>
<li class="failed">Rectangle-Circle Collision</li>
</ul>
<h2>Brief Wasm Series</h1>
<ul>
<li class="halfway">Getting started with WASM docs</li>
<li class="halfway">Wasm examples</li>
</ul>
<p style="color: black; font-size: 18px;">
Everything above has a due date of <b>April 30th, 2021</b>. None of it is that hard, so this should be a very doable timeline.
</p>
</section>
</article>
</main>
</body>
</html>
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