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#include "object.hpp"
#include <math.h>
#include <iostream>
#include "common.hpp"
Sphere::Sphere(Vec3d center, double radius) {
m_center = center;
m_radius = radius;
}
Plane::Plane(Vec3d start, Vec3d norm) {
m_start = start;
m_norm = norm;
m_norm.normalize();
}
Vec3d Sphere::norm_at(const Vec3d &point, const Vec3d&) const {
auto res = point - m_center;
res.normalize();
return res;
}
// https://www.scratchapixel.com/lessons/3d-basic-rendering/minimal-ray-tracer-rendering-simple-shapes/ray-sphere-intersection
double Sphere::intersect(const Ray &ray, bool skip_dist) const {
// Calculate O - C used multiple places
auto oc = ray.m_start - m_center;
// Calculate components of quadratic formula
// a = 1 when ray.direction is a unit vector
auto a = 1;
auto b = 2 * ray.m_direction.dot(oc);
auto c = oc.dot(oc) - m_radius * m_radius;
// Solve quadratic function
auto discr = b * b - 4 * a * c;
if (discr < 0) {
// No solution
return -1;
}
if (skip_dist) {
// Do not calculate distance
return 1;
}
auto q = (b > 0) ?
-0.5 * (b + sqrt(discr)):
-0.5 * (b - sqrt(discr));
auto t1 = q; // Assuming a = 1
auto t0 = c / q;
// Find correct result
if (t0 <= ZERO_APPROX) {
t0 = t1;
}
if (t0 <= ZERO_APPROX) {
return -1;
}
return t0;
}
Vec3d Plane::norm_at(const Vec3d&, const Vec3d &indir) const {
auto scale = m_norm.dot(indir);
return scale > 0 ? -m_norm : m_norm;
}
// https://www.scratchapixel.com/lessons/3d-basic-rendering/minimal-ray-tracer-rendering-simple-shapes/ray-plane-and-ray-disk-intersection
// Requires that vectors are normalized
// Skip dist is ignored as distance must be calculated
double Plane::intersect(const Ray &ray, bool) const {
// If ray is parallel
auto nr = m_norm.dot(ray.m_direction);
if (abs(nr) < ZERO_APPROX) {
return -1;
}
// Calculate distance
auto dist = m_norm.dot(m_start - ray.m_start) / nr;
if (dist < 0) {
return -1;
}
return dist;
}
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