Move rendering functions to own module
This commit is contained in:
155
src/camera.c
155
src/camera.c
@@ -1,125 +1,16 @@
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#include "camera.h"
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#include "ray.h"
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#include "rng.h"
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#include <float.h>
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#include <math.h>
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#include <stdatomic.h>
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#include <stdio.h>
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#include <threads.h>
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#ifndef M_PI
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#define M_PI 3.14159265258979323846264
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#endif
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#define MAX_ITER 200
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#define MIN_T 1e-6
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#define SAMPLE_STDDEV 0.333
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#define GAMMA 2.2
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#define NTHREADS 20
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typedef struct {
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const camera_t *camera;
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const scene_t *scene;
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pix_t *pixels;
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rng_t rng;
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unsigned start_y, row_count;
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atomic_uint *progress;
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} work_slice_t;
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static const vec3_t up = { 0.0, 1.0, 0.0 };
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static const vec3_t white = { 1.0, 1.0, 1.0 };
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static const vec3_t black = { 0.0, 0.0, 0.0 };
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static vec3_t trace(ray_t ray, const scene_t *scene, rng_t *rng)
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{
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vec3_t colour = white;
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for (unsigned i = 0; i < MAX_ITER; ++i) {
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hit_t hit = { .t = DBL_MAX };
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material_t material = {};
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for (unsigned j = 0; j < scene->obj_count; ++j) {
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const obj_t *obj = scene->objs + j;
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if (obj->intersect(obj->params, ray, &hit, MIN_T, hit.t))
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material = obj->material;
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}
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if (hit.t == DBL_MAX) {
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const double a = (ray.dir.y + 1.0) / 2.0;
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const vec3_t bg = vec3_add(
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vec3_scale(scene->sky_colour, a), vec3_scale(white, 1 - a));
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return vec3_hadamard(colour, bg);
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}
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vec3_t atten;
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if (!material.scatter(material.params, hit, rng, &ray, &atten))
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return black;
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colour = vec3_hadamard(colour, atten);
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}
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return black;
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}
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static double linear_to_gamma(double channel)
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{
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return pow(fmin(channel, 1.0), 1.0 / GAMMA);
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}
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static void setpix(vec3_t col, pix_t *out)
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{
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out->r = UINT16_MAX * linear_to_gamma(col.x);
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out->g = UINT16_MAX * linear_to_gamma(col.y);
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out->b = UINT16_MAX * linear_to_gamma(col.z);
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out->a = UINT16_MAX;
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}
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static int render_thread(void *arg)
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{
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work_slice_t *slice = (work_slice_t *)arg;
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const camera_t *camera = slice->camera;
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const uint32_t w = camera->img_width;
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const double sample_weight = 1.0 / (double)camera->samples_per_pixel;
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const unsigned stop_y = slice->start_y + slice->row_count;
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for (unsigned y = slice->start_y; y < stop_y; ++y) {
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const vec3_t row
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= vec3_add(camera->pix_origin, vec3_scale(camera->y_step, y));
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for (unsigned x = 0; x < w; ++x) {
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const vec3_t pix = vec3_add(row, vec3_scale(camera->x_step, x));
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vec3_t colour = black;
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for (unsigned i = 0; i < camera->samples_per_pixel; ++i) {
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const vec3_t jitter
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= rng_gaussian_xy(&slice->rng, SAMPLE_STDDEV);
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const vec3_t offset = vec3_add(
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vec3_scale(camera->x_step, jitter.x),
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vec3_scale(camera->y_step, jitter.y));
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const vec3_t jittered_pix = vec3_add(pix, offset);
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const ray_t ray = {
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.orig = camera->pos,
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.dir = vec3_unit(vec3_sub(jittered_pix, camera->pos)),
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};
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const vec3_t sample = trace(ray, slice->scene, &slice->rng);
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colour = vec3_add(colour, vec3_scale(sample, sample_weight));
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}
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setpix(colour, slice->pixels + (w * y + x));
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}
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atomic_fetch_add(slice->progress, 1);
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}
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return 0;
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}
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camera_t camera_init(
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vec3_t pos, vec3_t target, double fov, uint32_t img_width,
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uint32_t img_height, unsigned samples_per_pixel)
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uint32_t img_height)
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{
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const double fov_rad = M_PI * fov / 180.0;
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const double aspect = (double)img_width / (double)img_height;
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@@ -148,49 +39,5 @@ camera_t camera_init(
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.y_step = y_step,
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.img_width = img_width,
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.img_height = img_height,
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.samples_per_pixel = samples_per_pixel,
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};
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}
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void camera_render(
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const camera_t *camera, const scene_t *scene, img_t *img_out)
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{
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img_out->w = camera->img_width;
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img_out->h = camera->img_height;
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const unsigned rows = camera->img_height;
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const unsigned rows_per_thread = rows / NTHREADS;
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const unsigned rem_rows = rows % NTHREADS;
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atomic_uint progress = 0;
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thrd_t threads[NTHREADS];
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work_slice_t slices[NTHREADS];
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for (unsigned i = 0; i < NTHREADS; ++i) {
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slices[i].camera = camera;
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slices[i].scene = scene;
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slices[i].pixels = img_out->pix;
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slices[i].rng = rng_init(i);
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slices[i].start_y = i * rows_per_thread;
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slices[i].row_count = rows_per_thread;
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if (rem_rows != 0 && i == NTHREADS - 1)
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slices[i].row_count += rem_rows;
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slices[i].progress = &progress;
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thrd_create(threads + i, render_thread, slices + i);
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}
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const unsigned digits = (unsigned)floor(log(rows) / log(10)) + 1;
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unsigned done;
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do {
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thrd_sleep(&(struct timespec) { .tv_nsec = 50'000'000 }, nullptr);
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done = atomic_load(&progress);
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fprintf(stderr, "\r[%*d/%d]", digits, done, rows);
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fflush(stderr);
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} while (done < rows);
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for (unsigned i = 0; i < NTHREADS; ++i)
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thrd_join(threads[i], 0);
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}
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