From 2ab6b6cfe81505b029f2da397cef0bb58989444f Mon Sep 17 00:00:00 2001 From: Matthew Kosarek Date: Thu, 17 Jun 2021 21:32:57 -0400 Subject: (mkosarek) Beginning to explain rigidbody physics in a reasonable way --- 2d/rigidbody/rigidbody_1.html | 38 +++- 2d/rigidbody/rigidbody_1.html.content | 38 +++- 2d/rigidbody/rigidbody_1/dist/output.js | 313 ++++++++++++++++++------------ 2d/rigidbody/rigidbody_1/dist/output.wasm | Bin 47023 -> 47394 bytes 2d/rigidbody/rigidbody_1/main.cpp | 10 + 2d/rigidbody/rigidbody_1/snippet1.cpp | 8 + 2d/rigidbody/rigidbody_1/snippet2.cpp | 25 +++ index.html | 32 ++- index.html.content | 32 ++- roadmap.html | 1 + roadmap.html.content | 1 + shared_cpp/mathlib.h | 1 + 12 files changed, 332 insertions(+), 167 deletions(-) create mode 100644 2d/rigidbody/rigidbody_1/snippet1.cpp create mode 100644 2d/rigidbody/rigidbody_1/snippet2.cpp diff --git a/2d/rigidbody/rigidbody_1.html b/2d/rigidbody/rigidbody_1.html index 2c17bac..e7e848d 100644 --- a/2d/rigidbody/rigidbody_1.html +++ b/2d/rigidbody/rigidbody_1.html @@ -68,19 +68,51 @@

Rigidbody #1: Linear Forces

- In this first installment of my 2D rigidbody tutorial, we are going to explore linear forces and how we can begin to simulate them in real time on a computer. As you'll come to see, 2D forces are quite easy to understand and implement if you have some basic knowledge of 2D maths. On top of that, they really add a lot of life into what would otherwise be a static 2D scene. Without further ado, let's jump in. + In this first installment of my 2D rigidbody tutorial, we are going to explore linear forces and how we can begin to simulate them in real time on a computer. As you'll come to see, 2D forces are quite easy to understand and implement if you have some basic knowledge of 2D maths. On top of that, they really add a lot of life into what would otherwise be a static 2D scene.

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What is a Force Anyway?

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What do we mean by 'Rigid Body Physics'?

+ In implementing a rigidy body physics system, we're primarily interested in two sub-fields of physics, namely dynamics and kinematics. Although I'm + far as can be from being an expert in either of these fields, I will explain - from a programmer's perspective - what they mean to me: + + + + Although the distinction between these two subfields may seem inconsequential, it impacts the conceptual way in which we might begin to setup our 2D rigidbody simulation: the kinematic variables are the data that we act upon, while the dynamics variables are the data that we apply. + +
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The Kinematics Data Structure

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+ Now that we have that understanding, we can begin setting up our rigidbody data structure. + + {{{rigidbody_1/snippet1.cpp}}} + + As you can see, the base data structure exactly mirrors what we already know from 2D newtonian physics. +

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The Dynamics Functions

- + Now, let's put that Rigidbody data structure to work! As I mentioned earlier, you can think of dynamics as the input to the system. What we're going to do now is add a way to + + {{{rigidbody_1/snippet2.cpp}}}

Live Example

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+ That's all there is to a rigidbody system with 2D linear forces. Now let's see it in action. Click 'Play' on the WebAssembly demo below to see a square bouncing around the screen. When you drag the pointer through the square, we will apply a force equivalent to how fast you were moving your mouse in the direction that you were moving it. (The speed is capped in the demo, or else things get a little out of hand.) +