c++ - Wierd Raytracing Artifacts -


i trying create ray tracer using qt, have weird artifacts going on.

before implemented shading, had 4 spheres, 3 triangles , 2 bounded planes in scene. showed expected , color expected however, planes, see dots same color background. these dots stay static view position, if moved camera around dots move around well. affected planes , triangles , never appear on spheres. 1 implemented shading issue got worse. dots appear on spheres in light source, part affected diffuse. also, 1 plane of pure blue (rgb 0,0,255) has gone straight black. since have 2 planes switched colors , again blue 1 went black, it's color issue , not plane issue.

with shading, sorry color change on items

no shading, artifact seen in pink plane

if has suggestions problem or wants see particular code let me know.

#include "plane.h"  #include "intersection.h"    #include <math.h>  #include <iostream>    plane::plane(qvector3d bottomleftvertex, qvector3d toprightvertex, qvector3d normal, qvector3d point, material *material)  {      mincoords_.setx(qmin(bottomleftvertex.x(),toprightvertex.x()));      mincoords_.sety(qmin(bottomleftvertex.y(),toprightvertex.y()));      mincoords_.setz(qmin(bottomleftvertex.z(),toprightvertex.z()));      maxcoords_.setx(qmax(bottomleftvertex.x(),toprightvertex.x()));      maxcoords_.sety(qmax(bottomleftvertex.y(),toprightvertex.y()));      maxcoords_.setz(qmax(bottomleftvertex.z(),toprightvertex.z()));      normal_ = normal;      normal_.normalize();      point_ = point;      material_ = material;  }    plane::~plane()  {    }    void plane::intersect(qvector3d rayorigin, qvector3d raydirection, intersection* result)  {      if(normal_ == qvector3d(0,0,0)) //plane degenerate      {          cout << "degenerate plane" << endl;          return;      }      float mint;      //t = -normal*(origin-point) / normal*direction      float numerator = (-1)*qvector3d::dotproduct(normal_, (rayorigin - point_));      float denominator = qvector3d::dotproduct(normal_, raydirection);      if (fabs(denominator) < 0.0000001) //plane orthogonal view      {          return;      }      mint = numerator / denominator;      if (mint < 0.0)      {          return;      }      qvector3d intersectpoint = rayorigin + (raydirection * mint);      //check inside plane dimensions      if(intersectpoint.x() < mincoords_.x() || intersectpoint.x() > maxcoords_.x() ||         intersectpoint.y() < mincoords_.y() || intersectpoint.y() > maxcoords_.y() ||         intersectpoint.z() < mincoords_.z() || intersectpoint.z() > maxcoords_.z())      {          return;      }      //only update if closest object      if(result->distance_ > mint)      {          result->hit_ = true;          result->intersectpoint_ = intersectpoint;          result->normalatintersect_ = normal_;          result->distance_ = mint;          result->material_ = material_;      }  }

qvector3d mainwindow::traceray(qvector3d rayorigin, qvector3d raydirection, int depth)  {      if(depth > maxdepth)      {          return backgroundcolour;      }      intersection* rayresult = new intersection();      foreach (shape* shape, shapelist)      {          shape->intersect(rayorigin, raydirection, rayresult);      }      if(rayresult->hit_ == false)      {          return backgroundcolour;      }      else      {          qvector3d intensity = qvector3d(0,0,0);          qvector3d shadowray = pointlight - rayresult->intersectpoint_;          shadowray.normalize();          intersection* shadowresult = new intersection();          foreach (shape* shape, shapelist)          {              shape->intersect(rayresult->intersectpoint_, shadowray, shadowresult);          }          if(shadowresult->hit_ == true)          {              intensity += shadowresult->material_->diffuse_ * intensityambient;          }          else          {              intensity += rayresult->material_->ambient_ * intensityambient;              // diffuse              intensity += rayresult->material_->diffuse_ * intensitylight * qmax(qvector3d::dotproduct(rayresult->normalatintersect_,shadowray), 0.0f);              // specular              qvector3d r = ((2*(qvector3d::dotproduct(rayresult->normalatintersect_,shadowray))* rayresult->normalatintersect_) - shadowray);              r.normalize();              qvector3d v = rayorigin - rayresult->intersectpoint_;              v.normalize();              intensity += rayresult->material_->specular_ * intensitylight * pow(qmax(qvector3d::dotproduct(r,v), 0.0f), rayresult->material_->specularexponent_);          }          return intensity;      }  }

so figured out issues. due float being terrible @ precision, check < 0.0 intermittently fail because of floats precision. had add offset checks checking < 0.001.


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