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//
// Created by Keuin on 2022/4/12.
//
#ifndef RT_HITLIST_H
#define RT_HITLIST_H
#include "viewport.h"
#include "timer.h"
#include "bitmap.h"
#include "ray.h"
#include "vec.h"
#include "object.h"
#include <cstdlib>
#include <memory>
#include <limits>
#include <vector>
#include <iostream>
#include <cstdint>
//#define T_SIMPLE_COLOR
//#define T_NORM_VISUAL
#define T_DIFFUSE
// A world, T is color depth
template<typename T>
class hitlist {
std::vector<std::shared_ptr<object>> objects;
public:
hitlist() = default;
hitlist(hitlist &other) = delete; // do not copy the world
// Add an object to the world.
void add_object(std::shared_ptr<object> &&obj) {
objects.push_back(std::move(obj));
}
// Given a ray, compute the color.
pixel<T> color(ray3d r, random_uv_gen_3d &ruvg, uint_fast32_t max_recursion_depth = 64) const {
double decay = 1;
while (max_recursion_depth-- > 0) {
// Detect hits
bool hit = false;
double hit_t = std::numeric_limits<double>::infinity();
std::shared_ptr<object> hit_obj;
// Check the nearest object we hit
for (const auto &obj: objects) {
double t_;
if (obj->hit(r, t_, 0.0) && t_ < hit_t) {
hit = true;
hit_t = t_;
hit_obj = obj;
}
}
if (hit) {
#ifdef T_SIMPLE_COLOR
// simply returns color of the object
return hit_obj->color();
#endif
#ifdef T_NORM_VISUAL
// normal vector on hit point
const auto nv = hit_obj->normal_vector(r.at(hit_t));
// visualize normal vector at hit point
return pixel<T>::from_normalized(nv);
#endif
#ifdef T_DIFFUSE
const auto hit_point = r.at(hit_t); // hit point, on the surface
auto nv = hit_obj->normal_vector(hit_point);
if (dot(nv, r.direction()) > 0) return pixel<T>::black(); // discard rays from inner (or invert nv)
vec3d diffuse_target = hit_point + nv + ruvg();
decay *= 0.5; // lose 50% light when diffused
r = ray3d{hit_point, diffuse_target - hit_point}; // the new diffused ray we trace on
continue;
#endif
}
// Does not hit anything. Get background color (infinity)
const auto u = (r.direction().y + 1.0) * 0.5;
const auto c = mix(
pixel<T>::from_normalized(1.0, 1.0, 1.0),
pixel<T>::from_normalized(0.5, 0.7, 1.0),
1.0 - u,
u
);
#ifdef T_DIFFUSE
return decay * c;
#else
return c;
#endif
}
return pixel<T>::black(); // reached recursion time limit, very little light
}
};
using hitlist8b = hitlist<uint8_t>;
#endif //RT_HITLIST_H
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