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raytracing.html
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raytracing.html
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<html>
<head>
<title>RayTracing example</title>
</head>
<script type="x-shader/x-vertex" id="passThruVS">
attribute vec2 coord;
varying vec2 pos;
void main(void) {
pos = coord;
gl_Position = vec4(coord, 0, 1.0);
gl_PointSize = 1.0;
}
</script>
<script type="x-shader/x-fragment" id="rayTracingFS">
precision highp float;
varying vec2 pos;
const float THRESHOLD = 1e-4;
struct PointLight {
vec3 location;
vec3 color;
float attenuation;
};
struct Object {
// object origin
vec3 offs;
// Object rotation and scale matrices
mat3 rs, inv_rs;
vec3 color;
// Light coefficients
float ambient, diffuse, specular, reflect;
int type; // 1 <- sphere, 2 <- plane, 3 <- checkered sphere, 4 <- checkered plane
};
struct Camera {
vec3 location;
mat3 rotation;
};
struct Ray {
vec3 origin, dir;
};
struct SurfaceProps {
// Light coefficients
float ambient, diffuse, specular, reflect;
vec3 point;
vec3 color;
vec3 norm;
};
float sqr(float x) { return x*x; }
float sqr(vec3 x) { return dot(x, x);}
// Returns intersection point between ray and object or ray origin if there are no interesction
vec3 ObjectIntersect(in Object obj, in Ray ray) {
Ray lr = Ray(obj.rs * (ray.origin - obj.offs), obj.rs * ray.dir);
float distance = 0.0;
if (obj.type == 2 || obj.type == 4) {
// Intersection of ray with plane is a linear equation
float cf = lr.dir.z;
// Return early if ray directions is perpendicular to plane normal
if (abs(cf) < THRESHOLD) {
return ray.origin;
}
distance = -lr.origin.z / cf;
}
if (obj.type == 1 || obj.type == 3) {
// Intersection of ray with unit sphere is a quadratic equation
// len(lr.origin + distance*lr.dir) = 1
// which is identical to
// sqr(lr.dir)*sqr(distance) + 2*distance*dot(lr.dir, -lr.orig) + sqr(lr.orig) - 1 = 0
float dirlen = sqr(lr.dir);
float ocd = dot(-lr.origin, lr.dir);
float d4 = sqr(ocd) - dirlen*(sqr(lr.origin)-1.0);
if (d4 < 0.0) {
return ray.origin;
}
d4 = sqrt(d4);
distance = (ocd - d4) / dirlen;
if (distance < THRESHOLD) {
distance = (ocd + d4) / dirlen;
}
}
if (distance >= THRESHOLD) {
return ray.origin + obj.inv_rs * distance * lr.dir;
}
return ray.origin;
}
void ObjectFillProps(in Object obj, in vec3 point, out SurfaceProps props) {
props.point = point;
props.color = obj.color;
props.ambient = obj.ambient;
props.diffuse = obj.diffuse;
props.specular = obj.specular;
props.reflect = obj.reflect;
vec3 lpoint = obj.rs * (point - obj.offs);
vec2 uv;
// Compute norm
if (obj.type == 1 || obj.type == 3) {
// Normal to the sphere is vec from origin to point on surface
props.norm = normalize(props.point - obj.offs);
// UV coords of the sphere are spherical coords of point
uv = 3.0 * vec2(atan(lpoint.z, lpoint.x), asin(lpoint.y))/3.1415926;
} else {
// Normal to plane is constant
props.norm = obj.inv_rs * vec3(0, 0, 1);
// UV coords are simple xy of point in plane local coordinates
uv = .5 * lpoint.xy;
}
// Checkered pattern
if (obj.type == 3 || obj.type == 4) {
if (sign((fract(uv.x)-.5)*(fract(uv.y)-.5)) > 0.0) {
props.color = vec3(1.0)-obj.color;
}
}
}
// Scene defenition
const int numLights = 1;
const int numObjects = 5;
uniform Object objects[numObjects];
uniform PointLight lights[numLights];
uniform Camera camera;
bool Scene_Intersects(in Ray ray) {
for(int idx = 0; idx < numObjects; ++idx) {
if (sqr(ObjectIntersect(objects[idx], ray) - ray.origin) > THRESHOLD) {
return true;
}
}
return false;
}
int Scene_Intersect(in Ray ray, out SurfaceProps props) {
float bestDistance2 = 1e12;
int bestIdx = -1;
vec3 bestPoint;
for(int idx = 0; idx < numObjects; ++idx) {
vec3 point = ObjectIntersect(objects[idx], ray);
float d2 = sqr(point - ray.origin);
if (d2 >= THRESHOLD && d2 < bestDistance2) {
bestDistance2 = d2;
bestIdx = idx;
bestPoint = point;
}
}
if (bestIdx < 0) return bestIdx;
for(int idx = 0; idx < numObjects; ++idx) {
if (idx != bestIdx) continue;
ObjectFillProps(objects[idx], bestPoint, props);
}
// Invert normal if origin is under the surface pointing by normal
if (dot(ray.origin - props.point, props.norm) < 0.0) {
props.norm *= -1.0;
}
return bestIdx;
}
void main(void) {
Ray ray = Ray(camera.location, normalize(camera.rotation * vec3(.6 * pos.x, .6 * pos.y, 1.0)));
vec3 color = vec3(0.0);
float weight = 1.0;
SurfaceProps props;
for(int depth = 0; depth < 5; ++depth) {
int objIdx = Scene_Intersect(ray, props);
if (objIdx < 0) {
color += weight * vec3(0.196, 0.6, 0.8);
break;
}
color += weight * props.ambient * props.color;
for(int idx = 0; idx < numLights; ++idx) {
vec3 lightDir = lights[idx].location - props.point;
Ray lightRay = Ray(props.point, normalize(lightDir));
// Check if light is occluded
if (Scene_Intersects(lightRay)) continue;
float attenuation = sqr(lights[idx].attenuation)/dot(lightDir, lightDir);
float angle = abs(dot(lightRay.dir, props.norm));
if (angle < THRESHOLD) continue;
// Add diffuse light component
if (props.diffuse >= THRESHOLD)
color += weight*props.diffuse*angle*attenuation*lights[idx].color*props.color;
// Add specular light component using Blinn–Phong reflection mode
if (props.specular >= THRESHOLD) {
vec3 halfway = normalize(lightRay.dir - ray.dir);
color += weight*props.specular*attenuation*pow(dot(halfway, props.norm), 30.0)*lights[idx].color;
}
}
if (weight * props.reflect < THRESHOLD) {
break;
}
float viewAngle = dot(ray.dir, props.norm);
weight *= props.reflect;
ray.dir -= props.norm * 2.0 * viewAngle;
ray.origin = props.point;
}
gl_FragColor = vec4(color, 1.0);
}
</script>
<script type="text/javascript">
function rotateX(angle) {
const cos = Math.cos(angle);
const sin = Math.sin(angle);
return [
1, 0, 0,
0, cos, -sin,
0, sin, cos,
];
}
function rotateY(angle) {
const cos = Math.cos(angle);
const sin = Math.sin(angle);
return [
cos, 0, sin,
0, 1, 0,
-sin, 0, cos,
];
}
function rotateZ(angle) {
const cos = Math.cos(angle);
const sin = Math.sin(angle);
return [
cos, -sin, 0,
sin, cos, 0,
0, 0, 1,
];
}
function identity(scale=1) {
return [
scale, 0, 0,
0, scale, 0,
0, 0, scale,
];
}
function mulMatVec(mat, vec) {
return [
vec[0]*mat[0] + vec[1]*mat[1] + vec[2]*mat[2],
vec[0]*mat[3] + vec[1]*mat[4] + vec[2]*mat[5],
vec[0]*mat[6] + vec[1]*mat[7] + vec[2]*mat[8],
];
}
function mulMatMat(mata, matb) {
const c1 = mulMatVec(mata, [matb[0], matb[3], matb[6]])
const c2 = mulMatVec(mata, [matb[1], matb[4], matb[7]])
const c3 = mulMatVec(mata, [matb[2], matb[5], matb[8]])
return [
c1[0], c2[0], c3[0],
c1[1], c2[1], c3[1],
c1[2], c2[2], c3[2],
];
}
class GLContext {
constructor(canvas) {
if (canvas == null)
throw 'Can not find canvas';
const ctx = canvas.getContext('webgl');
if (ctx == null)
throw 'Can not get WebGL context...';
ctx.viewport(0, 0, canvas.clientWidth, canvas.clientHeight);
ctx.clearColor(0, 0, 0, 1.0);
ctx.clear(ctx.COLOR_BUFFER_BIT);
this._ctx = ctx;
this.PRIMITIVES = {
POINTS: ctx.POINTS,
LINE_STRIP: ctx.LINE_STRIP,
LINES: ctx.LINES,
TRIANGLE_STRIP: ctx.TRIANGLE_STRIP,
TRIANGLES: ctx.TRIANGLES,
};
this.VERTEX_SHADER = ctx.VERTEX_SHADER;
this.FRAGMENT_SHADER = ctx.FRAGMENT_SHADER;
}
getGLContext() {
if (!this._ctx) throw 'Missing context';
return this._ctx;
}
compileShader(type, source) {
const glCtx = this.getGLContext();
var rc = glCtx.createShader(type);
glCtx.shaderSource(rc, source);
glCtx.compileShader(rc);
if (!glCtx.getShaderParameter(rc, glCtx.COMPILE_STATUS)) {
throw glCtx.getShaderInfoLog(rc) + ' in ' + source;
}
return rc;
}
getElementById(id) {
const element = document.getElementById(id);
if (element == null) {
throw 'Can not find shader by element id ' + id;
}
return element;
}
compileShaderById(id) {
const glCtx = this.getGLContext();
const element = this.getElementById(id);
const source = element.innerHTML;
if (element.type === 'x-shader/x-vertex') {
return this.compileShader(glCtx.VERTEX_SHADER, source);
}
if (element.type === 'x-shader/x-fragment') {
return this.compileShader(glCtx.FRAGMENT_SHADER, source);
}
throw 'Unknown shader type ' + element.type;
}
linkProgram(shaders) {
const glCtx = this.getGLContext();
const rc = glCtx.createProgram();
for(var cnt = 0; cnt < shaders.length; cnt++) {
if (!shaders[cnt]) {
throw 'Can not link program with null shaders';
}
glCtx.attachShader(rc, shaders[cnt]);
}
glCtx.linkProgram(rc);
if (!glCtx.getProgramParameter(rc, glCtx.LINK_STATUS)) {
throw glCtx.getProgramInfoLog(rc);
}
return rc;
}
setUniformf(name) {
const glCtx = this.getGLContext();
const prog = glCtx.getParameter(glCtx.CURRENT_PROGRAM);
const idx = glCtx.getUniformLocation(prog, name);
if (arguments.length == 2)
glCtx.uniform1f(idx, arguments[1]);
else if (arguments.length == 3)
glCtx.uniform2f(idx, arguments[1], arguments[2]);
else if (arguments.length == 4)
glCtx.uniform3f(idx, arguments[1], arguments[2], arguments[3]);
else if (arguments.length == 5)
glCtx.uniform4f(idx, arguments[1], arguments[2], arguments[3], arguments[4]);
else
throw "Unsupported number of uniform arguments";
}
setMatrix3fv(name, v) {
const glCtx = this.getGLContext();
const prog = glCtx.getParameter(glCtx.CURRENT_PROGRAM);
const idx = glCtx.getUniformLocation(prog, name);
if (v.length != 9)
throw "Unexpected number of 3x3 matrix arguments";
glCtx.uniformMatrix3fv(idx, false, v);
}
setUniformi(name) {
const glCtx = this.getGLContext();
const prog = glCtx.getParameter(glCtx.CURRENT_PROGRAM);
const idx = glCtx.getUniformLocation(prog, name);
if (arguments.length == 2)
glCtx.uniform1i(idx, arguments[1]);
else if (arguments.length == 3)
glCtx.uniform2i(idx, arguments[1], arguments[2]);
else if (arguments.length == 4)
glCtx.uniform3i(idx, arguments[1], arguments[2], arguments[3]);
else if (arguments.length == 5)
glCtx.uniform4i(idx, arguments[1], arguments[2], arguments[3], arguments[4]);
else
throw "Unsupported number of uniform arguments";
}
draw2DArray(type, name, arr) {
const glCtx = this.getGLContext();
const prog = glCtx.getParameter(glCtx.CURRENT_PROGRAM);
const idx = glCtx.getAttribLocation(prog, name);
var buf = glCtx.createBuffer();
glCtx.bindBuffer(glCtx.ARRAY_BUFFER, buf);
glCtx.bufferData(glCtx.ARRAY_BUFFER, new Float32Array(arr), glCtx.STATIC_DRAW);
glCtx.enableVertexAttribArray(idx);
glCtx.vertexAttribPointer(idx, 2, glCtx.FLOAT, false, 0, 0);
glCtx.drawArrays(type, 0, arr.length/2);
glCtx.deleteBuffer(buf);
}
}
class RayTracerScene {
constructor(canvas) {
const ctx = new GLContext(canvas);
const prog = ctx.linkProgram(['passThruVS', 'rayTracingFS'].map(_ => ctx.compileShaderById(_)));
ctx.getGLContext().useProgram(prog);
this.ctx = ctx;
this.aspect = canvas.clientWidth/canvas.clientHeight;
this.setCamera();
// Spheres
this.setType(0, 3);
this.setOffs(0, 0, 1, 5);
this.setRotateAndScale(0, 0.0, 0, 0, 1.5);
this.setColor(0, 1, 1, 1);
this.setMaterialProps(0, .1, .5, .6);
this.setType(1, 1);
this.setOffs(1, -3, 0, 4);
this.setRotateAndScale(1, 0, 0, .0, 1);
this.setColor(1, 0, 1, 0);
this.setMaterialProps(1, .1, .5, .6, 0);
this.setType(2, 1);
this.setOffs(2, 2, 0, 3);
this.setRotateAndScale(2, 0, 0, 0, 1);
this.setColor(2, 1, 1, 0);
this.setMaterialProps(2, .2, .5, .6, .3);
this.setType(3, 3);
this.setOffs(3, 10, 3.5, 0);
this.setRotateAndScale(3, 0, 0, 0, 3);
this.setColor(3, 1, 1, 0);
this.setMaterialProps(3, .2, .3, .3, .5);
//plane
this.setType(4, 4);
this.setOffs(4, 0, -1, 0);
this.setRotateAndScale(4, -Math.PI/2, 0, 0, 1);
this.setColor(4, 0, 0, 1);
this.setMaterialProps(4, .1, .5, .4, .4);
// Lights
ctx.setUniformf('lights[0].location', 10, 5, -10);
ctx.setUniformf('lights[0].color', 1, 1, 1);
ctx.setUniformf('lights[0].attenuation', 17);
}
animate(t) {
this.setRotateAndScale(0, 0, 1e-3*t, 0, 1.5);
this.render();
}
render(x0 = -1.0, y0 = -1.0, x1 = 1.0, y1 = 1.0) {
this.ctx.draw2DArray(this.ctx.PRIMITIVES.TRIANGLE_STRIP, 'coord', [x0, y0, x1, y0, x0, y1, x1, y1]);
}
setColor(i, r, g, b) {
this.ctx.setUniformf('objects['+i+'].color', r, g, b);
}
setType(i, t) {
this.ctx.setUniformi('objects['+i+'].type', t);
}
setOffs(i, x, y, z) {
this.ctx.setUniformf('objects['+i+'].offs', x, y, z);
}
setRotateAndScale(i, longitude, latitude, spin, scale) {
var rs = mulMatMat(rotateZ(spin), mulMatMat(mulMatMat(rotateY(-latitude), rotateX(longitude)), identity(1/scale)));
var inv_rs = mulMatMat(rotateZ(-spin), mulMatMat(mulMatMat(rotateY(latitude), rotateX(-longitude)), identity(scale)));
this.ctx.setMatrix3fv('objects['+i+'].rs', rs);
this.ctx.setMatrix3fv('objects['+i+'].inv_rs', inv_rs);
}
setMaterialProps(i, a=0, d=0, s=0, r=0) {
this.ctx.setUniformf('objects['+i+'].ambient',a);
this.ctx.setUniformf('objects['+i+'].diffuse',d);
this.ctx.setUniformf('objects['+i+'].specular',s);
this.ctx.setUniformf('objects['+i+'].reflect',r);
}
setCamera(x=0, y=0, z=-1) {
this.ctx.setUniformf('camera.location', x, y, z);
this.ctx.setMatrix3fv('camera.rotation', [this.aspect, 0, 0, 0, 1, 0, 0, 0, 1]);
}
setCameraRotation(longitude, latitude, spin) {
var mat = mulMatMat(rotateY(-latitude), rotateX(longitude));
for(var i = 0; i < 3; i++) {
mat[3*i] *= this.aspect;
}
this.ctx.setMatrix3fv('camera.rotation', mat);
}
}
var orientationEventReceived = false;
function registerMotionEventListener() {
var compOrientation = {alpha: 0, beta: 0, gamma: 0};
window.addEventListener('devicemotion', function(event) {
orientationEventReceived = true;
compOrientation.alpha += event.rotationRate.alpha*event.interval;
compOrientation.beta += event.rotationRate.beta*event.interval;
compOrientation.gamma += event.rotationRate.gamma*event.interval;
const alpha = Math.PI* compOrientation.alpha / 180;
const beta = Math.PI* compOrientation.beta / 180;
const gamma = Math.PI* compOrientation.gamma / 180;
if (window.orientation == 0.0) {
scene.setCameraRotation(alpha, beta, gamma);
} else if (window.orientation == 90.0) {
scene.setCameraRotation(beta, alpha, alpha);
} else if (window.orientation == -90.0) {
scene.setCameraRotation(-beta, -alpha, alpha);
} else {
scene.setCameraRotation(0, 0, 0);
}
scene.render();
});
}
function requestPermissions() {
if (typeof DeviceMotionEvent === 'undefined') {
return;
}
if (typeof DeviceMotionEvent.requestPermission !== 'function') {
return;
}
DeviceMotionEvent.requestPermission(function(state) {
if (state == 'granted') {
registerMotionEventListener();
}
}).catch(console.error);
}
function displayClickToEnable() {
document.getElementById('click-to-enable').style.visibility='visible';
}
function configureTracer() {
const canvas = document.getElementById('canvas');
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
try {
scene = new RayTracerScene(canvas);
scene.render();
var cameraDistance = -1.0;
var xn = 0.0;
var yn = 0.0;
canvas.addEventListener('mousemove', function(event) {
xn = scene.aspect*(event.x/canvas.clientWidth - .5);
yn = (event.y/canvas.clientHeight - .5);
scene.setCamera(xn, yn, cameraDistance);
scene.render();
});
canvas.addEventListener('wheel', function(event) {
cameraDistance += 1e-3 * event.deltaY;
scene.setCamera(xn, yn, cameraDistance);
scene.render();
});
registerMotionEventListener();
setTimeout(function() {
if (orientationEventReceived) {
return;
}
displayClickToEnable();
}, 1500);
setInterval(function() {
scene.animate(performance.now());
}, 100);
} catch (e) {
alert('Initialization failed: ' + e);
return;
}
}
</script>
</script>
<body onLoad="configureTracer();">
<DIV>
<H1 style="display:inline">RayTracer as fragment shader</H1>
<DIV style="display:inline;visibility:hidden" id="click-to-enable">
<INPUT TYPE="submit" onClick="requestPermissions();" value="Click here to enable orientation events" />
</DIV>
<canvas id="canvas" width="1024px" height="1024px"></canvas>
</body>
</html>