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camera.c
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camera.c
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#include <math.h>
#include "vec3.h"
#include "ray.h"
#include "camera.h"
#include "rand.h"
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
void cray_camera_init(cray_camera *cam)
{
cray_camera_aperture(cam, 1.3);
cray_camera_lookfrom(cam, 3, 3, 2);
cray_camera_lookat(cam, 0, 0, -1);
cray_camera_vup(cam, 0, 1, 0);
cray_camera_vfov(cam, 20);
cray_camera_aspect(cam, 2.0);
cray_camera_focus_dist(cam, cray_camera_dist(cam));
cray_camera_update(cam);
}
cray_ray cray_camera_get_ray(cray_camera *cam, CRAYFLT s, CRAYFLT t)
{
cray_ray r;
vec3 tmp[2];
vec3 rd;
vec3 offset;
CRAYFLT var;
/* tmp[0] = s*horizontal + t*vertical - origin */
VEC3_MULS(cam->horizontal, s, tmp[0]);
VEC3_MULS(cam->vertical, t, tmp[1]);
VEC3_ADD(tmp[0], tmp[1], tmp[0]);
VEC3_ADD(cam->lower_left_corner, tmp[0], tmp[0]);
VEC3_SUB(tmp[0], cam->origin, tmp[0]);
rd = random_in_unit_disk();
VEC3_MULS(rd, cam->lens_radius, rd);
/* offset = u*rd.x + v*rd.y */
var = rd.x;
VEC3_MULS(cam->u, var, tmp[1]);
var = rd.y;
VEC3_MULS(cam->v, var, rd);
VEC3_ADD(tmp[1], rd, offset);
/* tmp[1] = origin + offset */
VEC3_ADD(cam->origin, offset, tmp[1]);
/* tmp[0] = tmp[0] - offset */
VEC3_SUB(tmp[0], offset, tmp[0]);
RAY_SET(r, tmp[1], tmp[0]);
return r;
}
void cray_camera_aperture(cray_camera *cam, CRAYFLT aperture)
{
cam->lens_radius = aperture / 2.0;
}
void cray_camera_vfov(cray_camera *cam, CRAYFLT vfov)
{
cam->vfov = vfov;
}
void cray_camera_update(cray_camera *cam)
{
CRAYFLT theta;
CRAYFLT half_height;
CRAYFLT half_width;
vec3 tmp[2];
CRAYFLT var;
/* TODO: fix redundancy here */
cam->origin = cam->lookfrom;
theta = cam->vfov * M_PI / 180.0;
half_height = tan(theta / 2.0);
half_width = cam->aspect * half_height;
/* w = unit_vector(lookfrom - lookat) */
VEC3_SUB(cam->lookfrom, cam->lookat, cam->w);
VEC3_UNIT_VECTOR(cam->w, var, cam->w);
/* u = unit_vector(cross(vup, w)) */
VEC3_CROSS(cam->vup, cam->w, cam->u);
VEC3_UNIT_VECTOR(cam->u, var, cam->u);
/* v = cross(w, u) */
VEC3_CROSS(cam->w, cam->u, cam->v);
/* tmp[0] = hw * fd * u */
var = half_width * cam->focus_dist;
VEC3_MULS(cam->u, var, tmp[0]);
/* tmp[1] = hh * fd * v */
var = half_height * cam->focus_dist;
VEC3_MULS(cam->v, var, tmp[1]);
/* tmp[0] = origin - tmp[0] */
VEC3_SUB(cam->origin, tmp[0], tmp[0]);
/* tmp[0] = tmp[0] - tmp[1] */
VEC3_SUB(tmp[0], tmp[1], tmp[0]);
/* tmp[1] = w * fd */
VEC3_MULS(cam->w, cam->focus_dist, tmp[1]);
/* lower_left_corner = tmp[0] - tmp[1] */
VEC3_SUB(tmp[0], tmp[1], cam->lower_left_corner);
/* horiz = 2 * hw * fd * u */
var = 2 * half_width * cam->focus_dist;
VEC3_MULS(cam->u, var, cam->horizontal);
/* vert = 2 * hh * fd * v */
var = 2 * half_height * cam->focus_dist;
VEC3_MULS(cam->v, var, cam->vertical);
}
void cray_camera_lookat(cray_camera *cam, CRAYFLT x, CRAYFLT y, CRAYFLT z)
{
VEC3_SET(cam->lookat, x, y, z);
}
void cray_camera_lookfrom(cray_camera *cam, CRAYFLT x, CRAYFLT y, CRAYFLT z)
{
VEC3_SET(cam->lookfrom, x, y, z);
}
void cray_camera_vup(cray_camera *cam, CRAYFLT x, CRAYFLT y, CRAYFLT z)
{
VEC3_SET(cam->vup, x, y, z);
}
void cray_camera_focus_dist(cray_camera *cam, CRAYFLT focus_dist)
{
cam->focus_dist = focus_dist;
}
void cray_camera_aspect(cray_camera *cam, CRAYFLT aspect)
{
cam->aspect = aspect;
}
CRAYFLT cray_camera_dist(cray_camera *cam)
{
vec3 tmp;
VEC3_SUB(cam->lookfrom, cam->lookat, tmp);
return VEC3_LENGTH(tmp);
}