TheRock/rocm-libraries/projects/hipthreads/examples/InOneWeekendRaytracer/step4-simdize/camera.h

#ifndef CAMERAH
#define CAMERAH
//==================================================================================================
// Written in 2016 by Peter Shirley <ptrshrl@gmail.com>
//
// To the extent possible under law, the author(s) have dedicated all copyright and related and
// neighboring rights to this software to the public domain worldwide. This software is distributed
// without any warranty.
//
// You should have received a copy (see file COPYING.txt) of the CC0 Public Domain Dedication along
// with this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
//==================================================================================================

#include "random.h"
#include "ray.h"

// M_PI is missing definiton on Windows
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif


__host__ __device__ vec3 random_in_unit_disk(RandState *randState) {
    vec3 p;
    do {
        p = 2.0f*vec3(random_double(randState),random_double(randState),0) - vec3(1,1,0);
    } while (dot(p,p) >= 1.0f);
    return p;
}

class camera {
    public:
        __host__ __device__ camera(vec3 lookfrom, vec3 lookat, vec3 vup, float vfov, float aspect, float aperture, float focus_dist) {
            // vfov is top to bottom in degrees
            lens_radius = aperture / 2.0f;
            float theta = vfov*((float)M_PI)/180.0f;
            float half_height = tan(theta/2.0f);
            float half_width = aspect * half_height;
            origin = lookfrom;
            w = unit_vector(lookfrom - lookat);
            u = unit_vector(cross(vup, w));
            v = cross(w, u);
            lower_left_corner = origin  - half_width*focus_dist*u -half_height*focus_dist*v - focus_dist*w;
            horizontal = 2.0f*half_width*focus_dist*u;
            vertical = 2.0f*half_height*focus_dist*v;
        }
        __device__ ray get_ray(float s, float t, RandState *randState) const {
            vec3 rd = lens_radius*random_in_unit_disk(randState);
            vec3 offset = u * rd.x() + v * rd.y();
            return ray(origin + offset, lower_left_corner + s*horizontal + t*vertical - origin - offset);
        }

        vec3 origin;
        vec3 lower_left_corner;
        vec3 horizontal;
        vec3 vertical;
        vec3 u, v, w;
        float lens_radius;
};

#endif