49 lines
1.8 KiB
C
49 lines
1.8 KiB
C
#include "camera.h"
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#include "point3.h"
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#include "utils.h"
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#include "vec3.h"
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#include <math.h>
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void camera_init(Camera *camera, Point3 look_from, Point3 look_at, Vec3 up,
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double vertical_fov, double aspect_ratio, double aperture,
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double focus_distance, double shutter_open,
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double shutter_close) {
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double theta = degrees_to_radians(vertical_fov);
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double h = tan(theta / 2.0);
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double viewport_height = 2.0 * h;
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double viewport_width = aspect_ratio * viewport_height;
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camera->w = vec3_normalize(point3_sub(look_from, look_at));
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camera->u = vec3_normalize(vec3_cross(up, camera->w));
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camera->v = vec3_cross(camera->w, camera->u);
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camera->origin = look_from;
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camera->horizontal = vec3_mul(focus_distance * viewport_width, camera->u);
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camera->vertical = vec3_mul(focus_distance * viewport_height, camera->v);
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Vec3 offset =
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vec3_add(vec3_div(camera->horizontal, 2), vec3_div(camera->vertical, 2));
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offset = vec3_add(offset, vec3_mul(focus_distance, camera->w));
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camera->lower_left_corner = point3_add(camera->origin, vec3_neg(offset));
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camera->lens_radius = aperture / 2.0;
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camera->shutter_open = shutter_open;
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camera->shutter_close = shutter_close;
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}
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Ray camera_get_ray(const Camera *camera, double s, double t) {
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Vec3 rd = vec3_mul(camera->lens_radius, vec3_random_in_unit_disk());
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Vec3 offset = vec3_add(vec3_mul(rd.x, camera->u), vec3_mul(rd.y, camera->v));
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Point3 screen_point = point3_add(
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camera->lower_left_corner,
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vec3_add(vec3_mul(s, camera->horizontal), vec3_mul(t, camera->vertical)));
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Vec3 direction = point3_sub(screen_point, camera->origin);
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return (Ray){
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.origin = point3_add(camera->origin, offset),
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.direction = vec3_sub(direction, offset),
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.time =
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random_double_in_range(camera->shutter_open, camera->shutter_close),
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};
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}
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