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RayTracer.cpp
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RayTracer.cpp
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#include "RayTracer.h"
#include <fstream>
#include <cmath>
#include <cfloat>
static bool valid = true;
struct Hit
{
Vector3d point;
Geometry* obj;
Hit& operator=(const Hit& hit)
{
point = hit.point;
obj = hit.obj;
return *this;
}
};
#pragma region Main Structure
RayTracer::RayTracer(nlohmann::json json_file)
:json_file(json_file)
{
PRINT("JSON file acquired!");
}
RayTracer::~RayTracer() {}
void RayTracer::run()
{
BuildScene();
for (Output* output : scene.GetOutputs())
{
SetupCamera(*output);
Trace(*output);
SaveToPPM(*output);
}
}
/// Builds scene from json file
void RayTracer::BuildScene()
{
PRINT("Building scene...");
nlohmann::json geo = json_file.at("geometry");
nlohmann::json light = json_file.at("light");
nlohmann::json output = json_file.at("output");
JSONReadGeometries(scene.GetGeometries(), geo);
JSONReadLights(scene.GetLights(), light);
JSONReadOutput(scene.GetOutputs(), output);
//#if _DEBUG
// scene->PrintGeometries();
// scene->PrintLights();
// scene->PrintOutput();
//#endif
}
void RayTracer::SetupCamera(const Output& output)
{
PRINT("Setting up the camera...");
Camera::GetInstance().SetData(output, RESOLUTION);
}
void RayTracer::Trace(const Output& output)
{
PRINT("Tracing...");
Camera& camera = Camera::GetInstance();
auto& output_buffer = camera.GetOutputBuffer();
size_t buffer_size = output_buffer.size();
Vector3d px, py;
uint32_t counter = 0;
bool use_AA = (output.HasGlobalIllumination() || output.AntiAliase()) && !scene.HasAreaLight(); // If scene has GL or AreaL then no AA
bool use_specular = !output.HasGlobalIllumination(); // If scene has GL then no specular light
// For each height, trace its row
for (uint32_t y = 0; y < camera.Height(); y++)
{
//std::cout << std::endl;
for (uint32_t x = 0; x < camera.Width(); x++)
{
Color final_ambient;
Color final_diffuse;
Color final_specular;
px = (camera.ScaledPixel() - (2.0f * x + 1.0f) * camera.PixelCenter()) * camera.Right(); //(2.0f * y + 1.0f) == 2k + 1 aka odd number
py = (camera.HalfImage() - (2.0f * y + 1.0f) * camera.PixelCenter()) * camera.Up(); //(2.0f * y + 1.0f) == 2k + 1 aka odd number
Vector3d pixel_shoot_at = camera.OriginLookAt() + px + py;
Ray ray = camera.MakeRay(pixel_shoot_at);
bool hit = Raycast(ray);
if (use_AA)
{
UseMSAA(px, py, final_ambient, final_diffuse, output, output.HasGlobalIllumination());
}
else // No AA
{
if (hit)
{
final_diffuse = GetDiffuseColor(ray, false);
final_ambient = GetAmbientColor(ray);
}
else
{
final_ambient = output.GetBgColor();
}
}
if (hit && use_specular) final_specular = GetSpecularColor(ray);
output_buffer[counter] = (final_ambient * camera.AmbientIntensity() + final_diffuse + final_specular).Clamp();
counter++;
}
}
}
void RayTracer::SaveToPPM(const Output& output)
{
Camera& camera = Camera::GetInstance();
PRINT("Saving output as " + output.GetFileName() + ".");
#if STUDENT_SOLUTION || COURSE_SOLUTION
std::ofstream ofs(output.GetFileName(), std::ios_base::out | std::ios_base::binary);
#else
std::ofstream ofs(".\\outputs\\" + output.GetFileName(), std::ios_base::out | std::ios_base::binary);
#endif
ofs << "P6" << std::endl << camera.Width() << ' ' << camera.Height() << std::endl << "255" << std::endl;
auto& buffer = camera.GetOutputBuffer();
size_t size = buffer.size();
for (uint32_t i = 0; i < size; i++) {
ofs << (char)(255.0f * buffer[i].r) << (char)(255.0f * buffer[i].g) << (char)(255.0f * buffer[i].b);
}
ofs.close();
PRINT("Done saving!");
}
#pragma endregion
#pragma region Raytracer Core
bool RayTracer::Raycast(Ray& ray, double max_distance)
{
auto hits = RaycastAll(ray, max_distance);
if (hits.empty()) return false;
// Find the nearest obj
for (auto& hit : hits)
{
if (ray.IsCloser(hit.point))
{
ray.SetClosestHit(hit.point, *hit.obj);
}
}
return true;
}
// Shoot a ray in the scene to find all objects that intersects it.
std::vector<Hit> RayTracer::RaycastAll(const Ray& ray, double max_distance = DBL_MAX)
{
auto& geometries = scene.GetGeometries();
std::vector<Hit> hits;
for (Geometry* geo : geometries)
{
bool hit = false;
Vector3d intersect;
if (geo->GetType().compare(RECTANGLE) == 0)
{
hit = IntersectCoor(ray, *((Rectangle*)geo), intersect);
}
else if (geo->GetType().compare(SPHERE) == 0)
{
hit = IntersectCoor(ray, *((Sphere*)geo), intersect);
}
if (hit && ray.GetDistance(intersect) < max_distance)
{
hits.push_back(Hit{ intersect, geo });
}
}
return hits;
}
/// SPHERE ///
bool RayTracer::IntersectCoor(const Ray& ray, Sphere& sphere, Vector3d& intersect)
{
double a, b, c;
Vector3d distance = ray.GetOrigin() - sphere.GetCenter();
a = ray.GetDirection().dot(ray.GetDirection());
b = 2.0f * ray.GetDirection().dot(distance);
c = distance.dot(distance) - sphere.GetRadius() * sphere.GetRadius();
double disc = YuMath::Discriminant(a, b, c);
if (disc < 0) return false; // Imaginary numbers
auto t = YuMath::Quadratic(a, b, c, disc);
double b_pos_length = (ray.GetPoint(t->b_pos) - ray.GetOrigin()).norm();
double b_neg_length = (ray.GetPoint(t->b_neg) - ray.GetOrigin()).norm();
// Saves the closest sphere hit point.
if (b_pos_length < b_neg_length) intersect = (ray.GetPoint(t->b_pos)); // point at b_pos is closer
else intersect = (ray.GetPoint(t->b_neg)); // point at b_neg is closer
return true;
}
/// RECTANGLE
bool RayTracer::IntersectCoor(const Ray& ray, Rectangle& rect, Vector3d& intersect)
{
auto vn = ray.GetDirection().dot(rect.GetNormal());
if (vn == 0) return false; // Checks if ray is parallele to plane, if parallele return false
auto t = (rect.GetP1() - ray.GetOrigin()).dot(rect.GetNormal()) / vn;
if (t == 0) return false;
auto hit_point = ray.GetPoint(t);
// Area Triangle Implementation
long double area1 = YuMath::TriangleArea(hit_point, rect.GetP1(), rect.GetP2());
long double area2 = YuMath::TriangleArea(hit_point, rect.GetP2(), rect.GetP3());
long double area3 = YuMath::TriangleArea(hit_point, rect.GetP3(), rect.GetP4());
long double area4 = YuMath::TriangleArea(hit_point, rect.GetP4(), rect.GetP1());
auto area_delta = rect.GetArea() - area1 - area2 - area3 - area4;
if (!(std::abs(area_delta) < 0.05f)) return false;// 0.05f is for truncation errors.
// To get this formula, first find formula for intersection between a plane and a line(ray)
// then to get your d = -(rect.GetP1().dot(rect.GetNormal())); // derived from "Scalar Form of the Equation of a Plane"
// finally, simplify it due to the cluster of negative sign and dot product.
intersect = hit_point;
return true;
}
// SPECULAR
Color RayTracer::GetSpecularColor(const Ray& ray)
{
//Keep for ref
//auto adjacent = normal * incoming.dot(normal);
//auto opposite = incoming - adjacent;
//Vector3d reflect = adjacent - opposite ;
Vector3d towards_camera = (Camera::GetInstance().Position() - ray.GetHitCoor()).normalized();
Color specular;
Vector3d hit_normal = GetNormal(ray);
auto& lights = scene.GetLights();
for (auto& light : lights)
{
if (light->GetType().compare(POINT_LIGHT) == 0)
{
PointLight& point = *(PointLight*)light;
Vector3d towards_light = (point.GetCenter() - ray.GetHitCoor()).normalized();
if (IsLightHidden(point.GetCenter(), ray))
{
specular += Color::Black();
continue;
}
//Phong
//Vector3d reflect = Reflect(hit_normal, towards_light);
//double cos_angle = towards_camera.dot(reflect) / (towards_camera.norm() * reflect.norm());
//Blinn-Phong
double cos_angle = BlinnPhong(hit_normal, towards_light, towards_camera);
if (cos_angle < 0.0f) continue;
specular += (light->GetSpecularIntensity() * ray.hit_obj->GetSpecularCoeff() * ray.hit_obj->GetSpecularColor() * std::pow(cos_angle, ray.hit_obj->GetPhongCoeff()));
}
else if (light->GetType().compare(AREA_LIGHT) == 0)
{
AreaLight& area = *(AreaLight*)light;
auto& hit_points = area.GetHitPoints();
Color spec;
for (Vector3d& point : hit_points)
{
Vector3d towards_light = (point - ray.GetHitCoor()).normalized();
if (IsLightHidden(point, ray))
{
specular += Color::Black();
continue;
}
//Phong
//Vector3d reflect = YuMath::Reflect(hit_normal, towards_light);
//double cos_angle = towards_camera.dot(reflect) / (towards_camera.norm() * reflect.norm());
double cos_angle = BlinnPhong(hit_normal, towards_light, towards_camera);
if (cos_angle < 0.0f) continue;
spec += (light->GetSpecularIntensity() * ray.hit_obj->GetSpecularCoeff() * ray.hit_obj->GetSpecularColor() * std::pow(cos_angle, ray.hit_obj->GetPhongCoeff()));
}
specular = spec / (double)hit_points.size();
}
}
return specular;
}
inline double RayTracer::BlinnPhong(const Vector3d& normal, const Vector3d& towards_light, const Vector3d& towards_camera)
{
return normal.dot((towards_light + towards_camera).normalized());
}
// DIFFUSE
Color RayTracer::GetDiffuseColor(const Ray& ray, bool gl = true)
{
auto& lights = scene.GetLights();
Color diffuse;
for (auto& light : lights)
{
if (light->GetType().compare(POINT_LIGHT) == 0)
{
PointLight& point = *(PointLight*)light;
diffuse += CalculatePointLightDiffuse(point.GetCenter(), light->GetDiffuseIntensity(), ray, gl);
}
else if (light->GetType().compare(AREA_LIGHT) == 0)
{
AreaLight& area = *(AreaLight*)light;
if (area.GetUseCenter())
{
diffuse += CalculatePointLightDiffuse(area.GetCenter(), light->GetDiffuseIntensity(), ray, gl);
}
else
{
auto& hit_points = area.GetHitPoints();
Color color;
for (Vector3d& point : hit_points)
{
color += CalculatePointLightDiffuse(point, light->GetDiffuseIntensity(), ray, gl);
}
diffuse += (color / (double)hit_points.size());
}
}
}
return diffuse;
}
Color RayTracer::CalculatePointLightDiffuse(const Vector3d& light_center, const Color& light_diffuse_intensity, const Ray& ray, bool& gl)
{
return Helper_CalculatePointLightDiffuse(light_center, light_diffuse_intensity, ray, 0, gl);
}
Color RayTracer::Helper_CalculatePointLightDiffuse(const Vector3d& light_center, const Color& light_diffuse_intensity, const Ray& ray, unsigned int hit_count, bool& gl)
{
Vector3d hit_normal = GetNormal(ray);
if (!gl // Not using global illum
|| hit_count >= Camera::GetInstance().MaxBounce()
|| CustomRandom::GetInstance().Generate() <= Camera::GetInstance().ProbeTerminate())
{
if (IsLightHidden(light_center, ray))
{
return Color::Black();
}
else
{
Vector3d towards_light = (light_center - ray.GetHitCoor()).normalized();
double cos_angle = towards_light.dot(hit_normal);
if (cos_angle < 0.0f) cos_angle = 0.0f;
Geometry* geo = ray.hit_obj;
return (geo->GetDiffuseColor() * geo->GetDiffuseCoeff() * light_diffuse_intensity * cos_angle);
}
}
//// Find next bounce (Try again)
for (size_t i = 0; i < 3; i++)
{
Ray next_ray(ray.GetHitCoor(), YuMath::RandomDir(hit_normal));
if (Raycast(next_ray))
{
Geometry* geo = ray.hit_obj;
Color color = (geo->GetDiffuseColor() * geo->GetDiffuseCoeff() * light_diffuse_intensity);
return color * (1.0f / (2.0f * PI)) + Helper_CalculatePointLightDiffuse(light_center, light_diffuse_intensity, next_ray, hit_count + 1, gl);
}
}
valid = false;
return Color::Black(); // If all else fails return black.
}
/// OTHERS
/// Finds the number to intersecting item between a light and a point
bool RayTracer::IsLightHidden(const Vector3d& light_center, const Ray& ray)
{
Vector3d towards_light = (light_center - ray.GetHitCoor());
double towards_light_distance = towards_light.norm();
towards_light.normalize();
Ray ray_towards_light(ray.GetHitCoor(), towards_light);
auto hits = RaycastAll(ray_towards_light, towards_light_distance);
std::vector<Hit> filtered_hits;
// Filter out objects that are not in between light & hit
for (Hit& hit : hits)
{
double to_light_dist = (hit.point - light_center).norm();
double to_hit_coor_dist = (hit.point - ray.GetHitCoor()).norm();
if (to_light_dist > 0.001f // Object is embedded in light
&& to_hit_coor_dist > 0.001f // Object is hit coordinate
&& to_light_dist <= towards_light_distance) // object is behind hit coor
{
filtered_hits.push_back(hit);
}
}
if (filtered_hits.size() > 0) return true;
return false;
}
void RayTracer::UseMSAA(const Vector3d& px, const Vector3d& py, Color& out_final_ambient, Color& out_final_diffuse, const Output& output, const bool& gl)
{
const uint16_t grid_height = Camera::GetInstance().GridHeight();
const uint16_t grid_width = Camera::GetInstance().GridWidth();
const double sample_size = Camera::GetInstance().SampleSize();
const double subpixel_center = Camera::GetInstance().PixelCenter() / (grid_height); // Why height, cause it is the "a" value
const unsigned int grid_cell_count = grid_height * grid_width;
const double subpixel_size = subpixel_center + subpixel_center;
//Scanline for each row -> column
for (uint32_t grid_y = 0; grid_y < grid_width; grid_y++)
{
for (uint32_t grid_x = 0; grid_x < grid_height; grid_x++) // Samples area color around the current pixel
{
Color diffuse, ambient;
unsigned int invalid_samples = 0;
for (uint16_t sample = 0; sample < sample_size; sample++)
{
Vector3d sub_px = px + (Camera::GetInstance().PixelCenter() - (2.0f * grid_x + 1.0f) * subpixel_center + CustomRandom::GetInstance().Generate(subpixel_size)) * Camera::GetInstance().Right(); //(2.0f * y + 1.0f) == 2k + 1 aka odd number
Vector3d sub_py = py + (Camera::GetInstance().PixelCenter() - (2.0f * grid_y + 1.0f) * subpixel_center + CustomRandom::GetInstance().Generate(subpixel_size)) * Camera::GetInstance().Up(); //(2.0f * y + 1.0f) == 2k + 1 aka odd number
Vector3d subpixel_shoot_at = Camera::GetInstance().OriginLookAt() + sub_px + sub_py;
Ray ray = Camera::GetInstance().MakeRay(subpixel_shoot_at);
valid = true;
if (Raycast(ray))
{
ambient += GetAmbientColor(ray) * Camera::GetInstance().AmbientIntensity();
diffuse += GetDiffuseColor(ray, gl);
if (!valid) invalid_samples++;
}
else
{
ambient += output.GetBgColor();
}
}
out_final_ambient += ambient / (sample_size - invalid_samples);
out_final_diffuse += diffuse / (sample_size - invalid_samples);
}
}
//Final Colors
out_final_ambient /= grid_cell_count;
out_final_diffuse /= grid_cell_count;
}
Color RayTracer::GetAmbientColor(const Ray& ray)
{
Geometry& geo = *ray.hit_obj;
return geo.GetAmbientColor() * geo.GetAmbientCoeff();
}
Vector3d RayTracer::GetNormal(const Ray& ray)
{
if (ray.hit_obj->GetType().compare(SPHERE) == 0) return (ray.GetHitCoor() - (*(Sphere*)(ray.hit_obj)).GetCenter()).normalized();
else if (ray.hit_obj->GetType().compare(RECTANGLE) == 0) return (*(Rectangle*)(ray.hit_obj)).GetNormal();
else {
PRINT("Something went wrong...");
return Vector3d();
}
}
#pragma endregion