javascript - Triangle intersection in raytracer not working -


i trying make own raytracer in javascript. far spheres work well. want expand capabilities include triangles, , there can go squares, cubes , beyond. code have finding intersections triangles follows

function triangleintersection(t, r) { var norm = trianglenormal(t); var dist = triangledistance(t); var = vector.dotproduct(r.vector, norm);  if (a === 0) {     return -1; } else {     var b = vector.dotproduct(norm, vector.add(r.point, vector.negative(vector.multiply(norm, dist))));     var d = -1 * b / a;      var qx = vector.scale(r.vector, d).x + r.point.x;     var qy = vector.scale(r.vector, d).y + r.point.y;     var qz = vector.scale(r.vector, d).z + r.point.z;      var q = new vector(qx, qy, qz);      var ca = vector.subtract(t.points[2], t.points[0]);     var qa = vector.subtract(q, t.points[0]);     var t1 = vector.dotproduct(vector.crossproduct(ca, qa), norm);      var bc = vector.subtract(t.points[1], t.points[2]);     var qc = vector.subtract(q, t.points[2]);     var t2 = vector.dotproduct(vector.crossproduct(bc, qc), norm);      var ab = vector.subtract(t.points[0], t.points[1]);     var qb = vector.subtract(q, t.points[1]);     var t3 = vector.dotproduct(vector.crossproduct(ab, qb), norm);      if ((t1 >= 0) && (t2 >= 0) && (t3 >= 0)) {         return 1 * b / a;     } else {         return -1;     } }

}

triangle objects have point array (points[]) , item 0 point a, item 1 point b , item 2 point c. parameter t 1 of these triangles. parameter r ray object, properties point origin, , vector, direction.

i have these functions finding normal , distance of triangle.

function trianglenormal(s) { var ca = vector.subtract(s.points[2], s.points[0]); var ba = vector.subtract(s.points[1], s.points[0]); var norm = vector.unitvector(vector.crossproduct(ca, ba));  return norm; }  function triangledistance(t) {     return vector.dotproduct(trianglenormal(t, 0), t.points[0]); }

when render scene triangle use in scene red colored. no matter how far move camera triangle fills whole scene red. not know why happens.

an important error in plane intersection code comparison operation:

a === 0

there 2 things wrong it:

  1. for ray tracing want ray hit planes in front of source, not behind it, need a < 0.

  2. even if did want ray hit planes behind it, must never equality operations between floating point values, because floating point calculations not exact. (you must abs(a) < 1e-6f or small value)


Comments

Post a Comment

Popular posts from this blog

What is happening when Matlab is starting a "parallel pool"? -

running parallel cpu processes in matlab starts command parpool() according documentation , function: [creates] special job on pool of workers, , [connects] matlab client parallel pool. this function takes bit of time execute, on order of 30 seconds. in other multi-cpu paradigms openmp, parallel execution seems totally transparent -- i've never noticed behavior analogous matlab (granted i'm not experienced parallel programming). so, happening between time parpool() called , when finishes executing? takes long? parallel computing toolbox enables run matlab code in parallel using several different paradigms (e.g. jobs , tasks, parfor , spmd , parfeval , batch processing), , run either locally (parallelised across cores in local machine) or remotely (parallelised across machines in cluster - either 1 own, or 1 in cloud). in of these cases, code run on matlab workers , copies of matlab without interactive desktop. if you're intending run on remo...
Read more

angular - DownloadURL return null in below code -

when change file updated in firebase storage when try downloadurl show null. filechange(event: any) { const imagefolder: string = this.employee.id; const filelist: filelist = event.target.files; const file: file = filelist[0]; const storageref = firebase.storage().ref().child(`${imagefolder}/profile.jpg`).put(file); console.log(storageref.snapshot.downloadurl); } the put() asynchronous. if want url after file uploaded have this: firebase.storage().ref().child(`${imagefolder}/profile.jpg`).put(file).then((snapshot) => { storageref = snapshot.downloadurl: console.log(snapshot.downloadurl); });
Read more

php - Cannot override Laravel Spark authentication with own implementation -

during login process of laravel spark need request token of remote api. api stores exact same users , passwords laravel spark application. therefore need username , non hashed password of user during authentication process. i thought overriding authenticated method solution problem. in routes/web.php override post /login endpoint , pointing endpoint own logincontroller: <?php namespace app\http\controllers\auth; use illuminate\support\facades\log; use illuminate\http\request; use laravel\spark\http\controllers\auth\logincontroller sparklogincontroller; class logincontroller extends sparklogincontroller { /** * create new login controller instance. * * @return void */ public function __construct() { parent::__construct(); } /** * handle successful authentication attempt. * * @param request $request * @param \illuminate\contracts\auth\authenticatable $user * @return response */ public fu...
Read more