Marbles Rayce

Custom Background Environments:
Background images are 360 degree views stored in equirectangular projection. To use a custom environment image go to Settings and set 'Background Environment' to 'CUSTOM' then click 'Browse' and select your background image file.
The 'Directional Lighting' textbox lets you set the sun direction and color to go along with the background, the first 3 values are the red, green and blue color intensities and the last 2 values is the light direction as yaw/pitch in radians.

HDRIHaven is a good source of CC0 equirectangular images.


Custom Courses:
To load a custom course select 'CUSTOM' and then click 'Browse' and select your custom course file. Be warned loading custom courses executes Javascript that could be malicious.

Designing your own course is a bit more difficult, courses are all procedural defined by code. Custom courses are a mix of Javascript and GLSL(ES 2) code, below is a example of a custom course file.
return [//custom course file begins with javascript that returns array of course information and functions /* marbles - array of marbles objects, used for spawning marbles courseLength - used for scaling course rng - a deterministic rng function used for randomizing the course randomv - an array of random floats from 0-1, the random values from the shader($RND0$,etc) */ function(marbles,courseLength,rng,randomv) { return [//return array of functions function() {//spawn camera function return [0,5,0,//initial camera x,y,z position 0,0//initial camera yaw/pitch rotation ]; }, function(m,sid) {//spawn marble function m.x = sid*0.5;//spawn marbles in row along x-axis m.y = 5; m.z = 0; m.vx = 0;//initial marble velocity m.vy = 0; m.vz = 0; m.red = 0.2+rng()*0.8;//random marble colors m.green = 0.2+rng()*0.8; m.blue = 0.2+rng()*0.8; }, function(x,y,z,g) {//gravity function, outputs gravity(g) at point(x,y,z) g[0] = 0;//x g[1] = -10;//y g[2] = 0;//z }, function(x,y,z) {//physics distance function used for collisions, returns distance to geometry at point(x,y,z) return y;//flat plane }, function(x,y,z) {//finish line function, returns distance to finish line return 1e8;//1e8 constant distance means theres no finish line } ]; }, 1,//physics drag 0//random shader define count, access these with $RND0$, $RND1$, etc and rndv array ]; //DIVIDER marks the end of javascript code and the beginning of GLSL $DIVIDER$ float scene(vec3 p) {//rendering distance function, returns distance to geometry at point(p) return p.y; } void material(vec3 p, out vec4 diffuse, out vec4 specular, out vec2 metal) {//material function outputs material(diffuse,specular,metal) at point(p) metal = vec2(.2,0.01);//metallic(x), roughness(y) float chk = mod(floor(abs(p.x))+floor(abs(p.z)),2.)*.8+.2;//checkerboard texturing diffuse = vec4(chk,chk,chk,0.);//diffuse color specular = vec4(1,1,1,0);//specular color }
Save this to 'customcourse.txt' and try it out. This will create a flat checkboard plane with no finish line, it's a good starting point for your course.

Now we will create a more advanced course that actually has a finish line, a half pipe with the finish line in the center. The distance field is just a flat plane with a sphere subtracted to make the half dome so its easy to do in GLSL and Javascript. Below is the code for the next example course. return [ function(marbles,courseLength,rng,randomv) {//function that returns array of course functions return [ function() {//spawn camera function return [0,0,0,//place camera in center of half pipe 0,0]; }, function(m,sid) {//spawn marble function //spawn marbles around circle var ang = (sid/marbles.length)*Math.PI*2.0, len = courseLength*2.0-0.4; m.x = Math.cos(ang)*len; m.y = 0; m.z = Math.sin(ang)*len; m.vx = 0;//start with zero velocity m.vy = 0; m.vz = 0; m.red = 0.2+rng()*0.8;//random marble colors m.green = 0.2+rng()*0.8; m.blue = 0.2+rng()*0.8; }, function(x,y,z,g) {//gravity function g[0] = 0;//x g[1] = -10;//y g[2] = 0;//z }, function(x,y,z) {//physics distance function return Math.max(y,-(Math.sqrt(x*x+y*y+z*z)-courseLength*2.0));//flat plane with sphere subtracted }, function(x,y,z) {//finish line function y += courseLength*2.0; return Math.sqrt(x*x+y*y+z*z)-0.4;//finish line is a spherical area in the center } ] }, 0.999,//tiny bit of drag to slow down marbles 3//random shader define count ]; $DIVIDER$ float scene(vec3 p) { //p.y is the flat plane from the first tutorial. //-(length(p)-COURSE_LENGTH*2.) with max function is the subtracted sphere. return max(p.y,-(length(p)-COURSE_LENGTH*2.)); } void material(vec3 p, out vec4 diffuse, out vec4 specular, out vec2 metal) { if (length(p.xz) < 0.4) {//check if at finish area in center metal = vec2(0); diffuse = vec4(1);//white emissive material } else { metal = vec2(.5,.5);//half metallic half rough diffuse = vec4($RND0$,$RND1$,$RND2$,0.);//random diffuse color specular = vec4(1,1,1,0); } }

You can also ask quesions and discuss Marble Rayce on the Discord.

Extra Resources:
Here are some more useful links and resources for creating courses:
Javascript Documentation
GLSL ES 2 Quick Reference
Shadertoy
Inigo Quilez