defocus-modules/include/defocus/defocus.h

#ifndef DEFOCUS_H
#define DEFOCUS_H

#include <stdint.h>

#ifdef __cplusplus

#ifdef _MSC_VER
#define DF_API extern "C" __declspec(dllexport)
#else
#define DF_API extern "C"
#endif

#else

#ifdef _MSC_VER
#define DF_API __declspec(dllexport)
#else
#define DF_API
#endif

#endif /* __cplusplus */

/* Useful constants */
#define DF_EPSF32 0.00001f
#define DF_PIF32 3.1415926f
#define DF_PI_OVER_4F32 (DF_PIF32 / 4.f)
#define DF_PI_OVER_2F32 (DF_PIF32 / 2.f)
#define DF_PI_OVER_180F32 (DF_PIF32 / 180.f)

#define DF_DEGREES_TO_RADIANS(deg) ((deg) * DF_PI_OVER_180F32)

#define DF_ARRAY_COUNT(A) (sizeof((A)) / sizeof((A)[0]))
#define DF_UNUSED(x) ((void)sizeof((x)))

/* Math stuff */

typedef struct
{
    float x;
    float y;
    float z;
} df_v3;

typedef struct
{
    float x;
    float y;
} df_v2;

typedef struct
{
    int x;
    int y;
} df_v2i;

/* Images */
typedef unsigned int df_image_handle;

DF_API df_image_handle df_load_image(const char *path, int *w, int *h);

/* cameras */

/* The camera data structs (df_pinhole_camera_data etc.) are defined here
 * to enable you to store these on the stack.
 * However - unless you know what you are doing (-: - you should treat these
 * structs as opaque.
 */

typedef struct
{
    df_v3 origin;
    df_v3 dir;
} df_ray;

/* A camera function takes the uv coordinates of the output pixel and generates a ray.
 * The sample index can be used to introduce some randomness for multi-sampling. */
typedef df_ray (*df_camera_fn)(float u, float v, unsigned int sample_idx, void *camera_data);

typedef struct
{
    df_v3 horizontal;
    df_v3 vertical;
    df_v3 lower_left;
    df_v3 origin;
} df_pinhole_camera_data;

/* Creates data for a pinhole camera.
 * The vertical fov (vfov) is given in degrees.
 */
DF_API df_pinhole_camera_data df_create_pinhole_camera_data(df_v3 look_from, df_v3 look_at, df_v3 up,
    float vfov, float aspect);

DF_API df_ray df_pinhole_camera(float u, float v, unsigned int sample_idx, void *camera_data);

typedef struct
{
    df_v3 horizontal;
    df_v3 vertical;
    df_v3 lower_left;
    df_v3 origin;
    float lens_radius;
} df_thin_lense_camera_data;

DF_API df_thin_lense_camera_data df_create_thin_lense_camera_data(df_v3 look_from, df_v3 look_at, df_v3 up,
    float vfov, float aspect, float aperture, float focal_distance);

DF_API df_ray df_thin_lense_camera(float u, float v, unsigned int sample_idx, void *camera_data);

/* Settings for the basic ray tracing function. */
typedef struct
{
    /* Width needs to be divisible by 4! */
    int image_width;
    int image_height;
    int samples_per_pixel;

    df_v3 look_from;
    df_v3 look_at;

    df_camera_fn camera;
    void *camera_data;
} df_trace_rays_settings;

/* Sphere shape */
typedef struct
{
    float center_x;
    float center_y;
    float center_z;
    float radius;
} df_sphere;

typedef struct
{
    float base_x;
    float base_y;
    float base_z;
    float normal_x;
    float normal_y;
    float normal_z;

    /* Coordinates on the plane */
    float img_p0_x;
    float img_p0_y;
    float img_p0_z;
    float img_w;
    float img_h;

    /* TODO(Kevin): These could be calculated from p0 and p1 (p0+wh)... */
    float img_ax0_x;
    float img_ax0_y;
    float img_ax0_z;
    float img_ax1_x;
    float img_ax1_y;
    float img_ax1_z;
    df_image_handle image;
} df_plane;

DF_API float df_max_f32(const float *list, unsigned int count);

/* Core function, implements raytracing.
 *  
 * The result buffer receives RGB pixels, with 8 bits per channel stored in RGB order.
 * It is allocated via malloc().
 * 
 * Returns 1 on success, 0 if allocating the result image failed.
 */
DF_API int df_trace_rays(df_trace_rays_settings settings, const df_sphere *spheres, unsigned int sphere_count,
    const df_plane *planes, unsigned int plane_count, uint8_t **result);

#endif