1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
|
#include "render.hpp"
#include "core/vector.hpp"
#include "core/common.hpp"
#include <cstdlib>
#include <math.h>
#include <iostream>
#define FOV 1.74533
// Uniform sampling
#define SAMPLING_POWER 0
const Vec3d up = Vec3d(0, 1, 0);
void Random::seed(unsigned seed) {
for (unsigned i = 0; i < seed; i++) {
rand_r(&m_seed);
}
}
double Random::operator()() {
return (double)rand_r(&m_seed) / (double)RAND_MAX;
}
Sampler::Sampler(Random &src) : m_src(src) { }
Vec3d Sampler::sample(const Vec3d &norm) {
/*
auto theta = asin(pow(1 - random(), (double)1 / (1 + SAMPLING_POWER)));
auto phi = 2 * M_PI * random();
*/
auto theta = 2.0 * M_PI * m_src();
auto phi = acos(2.0 * m_src() - 1.0);
auto sinphi = sin(phi);
auto newvec = Vec3d(cos(theta) * sinphi, sin(theta) * sinphi, cos(phi));
if (newvec.dot(norm) <= 0) {
newvec = -newvec;
}
return newvec;
}
Renderer::Renderer(const Scene &scn, Vec3d eye, Vec3d target, unsigned width, unsigned height, unsigned maxhops) :
m_sampler(m_random),
m_scn(scn)
{
m_eye = eye;
m_target = target;
m_width = width;
m_height = height;
m_maxhops = maxhops;
recalculate();
}
void Renderer::recalculate() {
auto tmp = m_target - m_eye;
// Orthogonal vector to E
auto b = up.cross(tmp);
b.normalize();
tmp.normalize();
auto v = tmp.cross(b);
// Calculate size of viewplane
double gx = tan( FOV / 2);
double gy = gx * ((double) m_height / m_width);
// Calculate scaling vectors
m_qx = b * ((2 * gx) / (m_width - 1));
m_qy = v * ((2 * gy) / (m_height - 1));
// Calculate starting point
m_blc = tmp - (b * gx) - (v * gy);
}
Ray Renderer::findray(double x, double y) const {
auto dir = m_blc + (m_qx * x) + (m_qy * y);
return Ray(m_eye, dir, true);
}
Spectrum Renderer::render(unsigned x, unsigned y, unsigned samples) {
Spectrum sum;
for (unsigned i = 0; i < samples; i++) {
auto r = findray(x + m_random(), y + m_random());
sum += pathtrace_sample(r, 0);
}
if (samples < 2) {
return sum;
} else {
return sum / (double)samples;
}
}
Spectrum Renderer::pathtrace_sample(const Ray &r, unsigned hop) {
if (hop >= m_maxhops) {
return Spectrum();
}
double dist;
auto res = cast_ray(r, 0, &dist);
if (!res) {
return Spectrum();
}
auto col = res->m_mat.emits();
if (res->m_mat.reflects()) {
// Calculate endpoint
auto end = r.m_start + r.m_direction * dist;
auto norm = res->norm_at(end, r.m_direction);
auto randdir = m_sampler.sample(norm);
auto newray = Ray(end, randdir, true);
auto incol = pathtrace_sample(newray, hop+1);
col += res->m_mat.reflect(norm, newray.m_direction, r.m_direction, incol);
}
return col;
}
const Shape* Renderer::cast_ray(const Ray &r, double chk_dist, double *dist_ret) {
const Shape *smallest = nullptr;
double dist = 0;
for (auto obj : m_scn.objs) {
if (!obj) {
continue;
}
auto d = obj->intersect(r, false);
if (d > ZERO_APPROX) {
if (chk_dist > 0 && d < chk_dist) {
dist = d; smallest = obj;
goto exit;
}
if (d < dist || smallest == nullptr) {
dist = d; smallest = obj;
}
}
}
if (chk_dist > 0) {
// If we reach this it means none of the
// object where within distance.
return nullptr;
}
exit:
if (dist_ret) {
*dist_ret = dist;
}
return smallest;
}
|
