Live Demo

Ray Marched Volume

In order to hit the volumetric fire-y look that I wanted, I faked a volume by ray marching. In my vertex shader I displaced the original sphere with two levels of noise (one low frequency high aplitude pass to make the overall shape less sphere like, and one high frequency low aplitude pass to give the surface more detailed distortion). Both of these displacements are animated over time by moving the input position based on time so the fire appears to be moving up.

Then in my fragment shader I mimicked ray marching an SDF. For my "SDF" (in quotes because its not fully accurate, more on that later), I added distance from the sphere with amount of displacement for the noise. I return color of each fragment based the distance this "SDF" returns, giving the fire a layer multicolored look. However, I wanted a way to make the fire look smaller and less dense so it could fade out at the top and pulse with the music. To do this, I actually use a fake radius (not the actual radius of the orignal sphere) in my "SDF". When this is lower it has the effect of looking like a smaller, thinner volume. I use an easing function to mix between values for this fake radius from the bottom to the top of the fire to give the illusion that the fire fades into smoke at the top. I also use another easing function to change the color and transparency of the smoke from bottom to top.

Audio Input

The other main feature I focused on was having my fire change based on audio input. I made it so a button in the website plays a song (I chose a song called burn lol I thought it was funny at first but around time 100 of hearing it I kind of regretted not picking a song I liked more). The amplitude of the lower frequency sounds in the song affects the fake radius, making the fire appear to pulse with the lower beats. The amplitude of the higher frequency sounds affect the color, so the fire seems to glow bright red at higher pitched percussion and vocals. Specifically, this value is plugged into a bias for the value that affects the transition between bottom and top colors of the fire.

Input controls

Color controls: These control the colors of the fire. The smoke controls are the color of the top of the mesh, and the fire controls are the color of the bottom of the mesh. The inner, middle, outer layers refer to the distance from the edge of the fire that the color is applied.

Burn speed: Burn speed controls how quickly the input position of the fbm is changed based on time, giving the illusion of the fire rising faster/slower.

Fire density: The fire density controls both the transparency of the fire and the "fake radius" in the SDF function. Combined, these make it look like the fire is getting denser/thinner.

Reset: This button resets the above settings to defaults.

Play music: This button plays and pauses the music (which loops when the song finishes).

Project 1: Noise

Objective

Get comfortable with using WebGL and its shaders to generate an interesting 3D, continuous surface using a multi-octave noise algorithm.

Getting Started

1. Fork and clone this repository.

2. Copy your hw0 code into your local hw1 repository.

3. In the root directory of your project, run npm install. This will download all of those dependencies.

4. Do either of the following (but I highly recommend the first one for reasons I will explain later).

   a. Run npm start and then go to localhost:7000 in your web browser

   b. Run npm run build and then go open index.html in your web browser

   You should hopefully see the framework code with a 3D cube at the center of the screen!

Developing Your Code

All of the JavaScript code is living inside the src directory. The main file that gets executed when you load the page as you may have guessed is main.js. Here, you can make any changes you want, import functions from other files, etc. The reason that I highly suggest you build your project with npm start is that doing so will start a process that watches for any changes you make to your code. If it detects anything, it'll automagically rebuild your project and then refresh your browser window for you. Wow. That's cool. If you do it the other way, you'll need to run npm build and then refresh your page every time you want to test something.

Publishing Your Code

We highly suggest that you put your code on GitHub. One of the reasons we chose to make this course using JavaScript is that the Web is highly accessible and making your awesome work public and visible can be a huge benefit when you're looking to score a job or internship. To aid you in this process, running npm run deploy will automatically build your project and push it to gh-pages where it will be visible at username.github.io/repo-name.

Setting up main.ts

Alter main.ts so that it renders the icosphere provided, rather than the cube you built in hw0. You will be writing a WebGL shader to displace its surface to look like a fireball. You may either rewrite the shader you wrote in hw0, or make a new ShaderProgram instance that uses new GLSL files.

Noise Generation

Across your vertex and fragment shaders, you must implement a variety of functions of the form h = f(x,y,z) to displace and color your fireball's surface, where h is some floating-point displacement amount.

• Your vertex shader should apply a low-frequency, high-amplitude displacement of your sphere so as to make it less uniformly sphere-like. You might consider using a combination of sinusoidal functions for this purpose.
• Your vertex shader should also apply a higher-frequency, lower-amplitude layer of fractal Brownian motion to apply a finer level of distortion on top of the high-amplitude displacement.
• Your fragment shader should apply a gradient of colors to your fireball's surface, where the fragment color is correlated in some way to the vertex shader's displacement.
• Both the vertex and fragment shaders should alter their output based on a uniform time variable (i.e. they should be animated). You might consider making a constant animation that causes the fireball's surface to roil, or you could make an animation loop in which the fireball repeatedly explodes.
• Across both shaders, you should make use of at least four of the functions discussed in the Toolbox Functions slides.

Noise Application

View your noise in action by applying it as a displacement on the surface of your icosahedron, giving your icosahedron a bumpy, cloud-like appearance. Simply take the noise value as a height, and offset the vertices along the icosahedron's surface normals. You are, of course, free to alter the way your noise perturbs your icosahedron's surface as you see fit; we are simply recommending an easy way to visualize your noise. You could even apply a couple of different noise functions to perturb your surface to make it even less spherical.

In order to animate the vertex displacement, use time as the third dimension or as some offset to the (x, y, z) input to the noise function. Pass the current time since start of program as a uniform to the shaders.

For both visual impact and debugging help, also apply color to your geometry using the noise value at each point. There are several ways to do this. For example, you might use the noise value to create UV coordinates to read from a texture (say, a simple gradient image), or just compute the color by hand by lerping between values.

Interactivity

Using dat.GUI, make at least THREE aspects of your demo interactive variables. For example, you could add a slider to adjust the strength or scale of the noise, change the number of noise octaves, etc.

Add a button that will restore your fireball to some nice-looking (courtesy of your art direction) defaults. :)

Extra Spice

Choose one of the following options:

• Background (easy-hard depending on how fancy you get): Add an interesting background or a more complex scene to place your fireball in so it's not floating in a black void
• Custom mesh (easy): Figure out how to import a custom mesh rather than using an icosahedron for a fancy-shaped cloud.
• Mouse interactivity (medium): Find out how to get the current mouse position in your scene and use it to deform your cloud, such that users can deform the cloud with their cursor.
• Music (hard): Figure out a way to use music to drive your noise animation in some way, such that your noise cloud appears to dance.

Submission

• Update README.md to contain a solid description of your project
• Publish your project to gh-pages. npm run deploy. It should now be visible at http://username.github.io/repo-name
• Create a pull request to this repository, and in the comment, include a link to your published project.
• Submit the link to your pull request on Canvas.