89 lines
2.3 KiB
C++
89 lines
2.3 KiB
C++
#include <random>
|
|
#include <chrono>
|
|
#include <functional>
|
|
|
|
#include <glm/glm.hpp>
|
|
#include <glm/gtc/constants.hpp>
|
|
|
|
#include "sampling.hpp"
|
|
|
|
using std::uniform_real_distribution;
|
|
using std::mt19937;
|
|
using std::bind;
|
|
using glm::mat3;
|
|
using glm::abs;
|
|
using glm::normalize;
|
|
using glm::cross;
|
|
using glm::radians;
|
|
using glm::pi;
|
|
|
|
const float PDF = (1.0f / (2.0f * pi<float>()));
|
|
|
|
static bool seeded = false;
|
|
static uniform_real_distribution<float> dist(0, 1);
|
|
static mt19937 engine;
|
|
static auto generator = bind(dist, engine);
|
|
|
|
float random01() {
|
|
if (!seeded)
|
|
engine.seed(std::chrono::system_clock::now().time_since_epoch().count());
|
|
return generator();
|
|
}
|
|
|
|
vec2 sample_pixel(int i, int j, float w, float h, float a_ratio, float fov) {
|
|
float pxNDC;
|
|
float pyNDC;
|
|
float pxS;
|
|
float pyS;
|
|
pyNDC = (static_cast<float>(i) + random01()) / h;
|
|
pyS = (1.0f - (2.0f * pyNDC)) * glm::tan(radians(fov / 2.0f));
|
|
pxNDC = (static_cast<float>(j) + random01()) / w;
|
|
pxS = (2.0f * pxNDC) - 1.0f;
|
|
pxS *= a_ratio * glm::tan(radians(fov / 2.0f));
|
|
|
|
return vec2(pxS, pyS);
|
|
}
|
|
|
|
/* Sampling functions pretty much taken from scratchapixel.com */
|
|
void create_coords_system(const vec3 &n, vec3 &nt, vec3 &nb) {
|
|
if (abs(n.x) > abs(n.y))
|
|
nt = normalize(vec3(n.z, 0.0f, -n.x));
|
|
else
|
|
nt = normalize(vec3(0.0f, -n.z, n.y));
|
|
nb = normalize(cross(n, nt));
|
|
}
|
|
|
|
vec3 sample_hemisphere(const float r1, float r2) {
|
|
float sin_t = glm::sqrt(1.0f - (r1 * r1));
|
|
float phi = 2 * pi<float>() * r2;
|
|
float x = sin_t * glm::cos(phi);
|
|
float z = sin_t * glm::sin(phi);
|
|
return vec3(x, r1, z);
|
|
}
|
|
|
|
void rotate_sample(vec3 & sample, const vec3 & n) {
|
|
vec3 nt, nb;
|
|
mat3 rot_m;
|
|
|
|
create_coords_system(n, nt, nb);
|
|
sample = vec3(sample.x * nb.x + sample.y * n.x + sample.z * nt.x,
|
|
sample.x * nb.y + sample.y * n.y + sample.z * nt.y,
|
|
sample.x * nb.z + sample.y * n.z + sample.z * nt.z);
|
|
}
|
|
|
|
vec3 sample_sphere(const vec3 center, const float radius) {
|
|
float theta;
|
|
float u, sqrt1muu, x, y, z;
|
|
|
|
// Sampling formula from Wolfram Mathworld:
|
|
// http://mathworld.wolfram.com/SpherePointPicking.html
|
|
theta = random01()* (2.0f * pi<float>());
|
|
u = (random01() * 2.0f) - 1.0f;
|
|
sqrt1muu = glm::sqrt(1.0f - (u * u));
|
|
x = radius * sqrt1muu * cos(theta);
|
|
y = radius * sqrt1muu * sin(theta);
|
|
z = radius * u;
|
|
|
|
return vec3(vec3(x, y, z) + center);
|
|
}
|