PENUMBRA

      const float RAYMARCH_MIN_DIST = 0.3;
const float RAYMARCH_MAX_DIST = 50.0;
const float RAYMARCH_HIT_CUTOFF = 0.001;
const int RAYMARCH_MAX_ITERS = 32;
const float CAMERA_FOV = 0.3;
const vec3 LIGHT_POS = vec3(-2.0, 2.0, -1.0);
const float PI = 3.14159265358979323846;
const float DEG2RAD = PI / 180.0;
const float ANIM_SPEED = 1.0;
float clamp01(float x) { return clamp(x, 0.0, 1.0); }
vec3 clamp01(vec3 x) { return clamp(x, 0.0, 1.0); }
vec3 rotateX(vec3 p, float a) {
  float c = cos(a), s = sin(a);    
  return vec3(p.x, c * p.y - s * p.z, s * p.y + c * p.z);    
}
vec3 rotateY(vec3 p, float a) {
  float c = cos(a), s = sin(a);    
  return vec3(c * p.x + s * p.z, p.y, -s * p.x + c * p.z);    
}

getting started.

Penumbra is a Hack Club YSWS (You Ship, We Ship) program, where you ship art made with shaders, and we ship you posters of that art, free of charge! We're also giving away GPUs for the most dedicated.

Join the Slack and setup Hackatime

Create shaders with ShaderToy

Submit and get them as posters

20+ hrs of extra work = GPU!

We will use a local poster printing service in your country in order to ship your poster.

GPU milestones.

If you have more than 4 hours of work on a submission, the extra time will be counted towards getting a GPU. These can be spread across multiple shader submissions. We'll give you a grant depending on how long you've coded for in total.

20 hours: up to $100 - e.g. NVIDIA GeForce GT 1030
30 hours: up to $150 - e.g. AMD RX 560, Intel Arc A380
40 hours: up to $200 - e.g. NVIDIA RTX 3050, AMD RX 6500
50 hours: up to $250 - e.g. AMD RX 6600, Intel Arc B570

If you want all of your coding time to count as extra time, you can choose not to receive a poster. The caveat is that you won't get a really cool poster... :(

setting up.

To get started, join our Slack and set up Hackatime! We use Slack as our primary communication platform. Hackatime is our custom WakaTime server to track your coding time. You can use it with the WakaTime for ShaderToy browser extension!

Join the Slack

Set-up WakaTime with Hackatime

Install the Chrome extension

Install the Firefox extension

Have fun on ShaderToy!

what's a shader?

For each pixel coordinate, a “fragment” shader will return its color!

This language is called GLSL - the OpenGL Shading Language. Try messing around with the sandbox above!

You're given UV coordinates: they range from 0.0 to 1.0. (0.0, 0.0) is the bottom-right corner, and (1.0, 1.0) is the top-left one. The center of the screen is at (0.5, 0.5).

There are multiple approaches to making art with shaders! Because what you're writing is just a function, try using random math formulas, and see what happens!

If you want to do 3D, you are probably searching for raymarching. You can learn more about it with the guides in the next section!

resources & guides.

If you ever are stuck, don't be afraid to ask in the #penumbra Slack channel. For inspiration, take a look at ShaderToy's Browse tab! It's full of fancy shaders, all with code!

If you're just starting out, or need a refresher, watch kishimisu's fantastic introduction to the world of making art with shaders!

If you're interested in 3D raymarching, these might come in handy:

submit.

Before you submit - make sure you:

joined our Slack
measured your coding time with Hackatime
have your shader published on ShaderToy AND a Git repository

You'll need to work at least 4 hours on your shader for it to qualify to get a free poster.

SUBMIT A SHADER

If you work on a shader for more than 4 hours, the extra time is counted towards a GPU. You can choose to opt out of a poster in order to get all of your hours counted towards this goal - but then you won't get a really cool poster...

REQUEST A GPU