defocus-modules/include/defocus/base.h

#ifndef DEFOCUS_BASE_H
#define DEFOCUS_BASE_H

#include <inttypes.h>
#include <string.h>

/** @file base.h
 * @brief basic utilities
 */

/** @brief Result codes used throughout the codebase */
typedef enum
{
    /** @brief operation successfull */
    df_result_success = 0,

    /** @brief an opengl error occured */
    df_result_gl_error = 1,

    /** @brief memory allocation failed */
    df_result_out_of_memory = 2,

    /** @brief file i/o error */
    df_result_io_error = 3,
} df_result;

/** @brief Used to silence warnings about unused variables */
#define DF_UNUSED(x) ((void)sizeof((x)))

/** @brief Evaluates to the number of elements in a static array. */
#define DF_ARRAY_COUNT(a) (sizeof((a)) / sizeof((a)[0]))

/** @brief Zero a memory range */
#define DF_ZERO_MEMORY(ptr, n) memset((ptr), 0, (n))

/** @brief Zero a struct */
#define DF_ZERO_STRUCT(ptr) DF_ZERO_MEMORY(ptr, sizeof(*(ptr)))

/** @brief Zero an array */
#define DF_ZERO_ARRAY(a, n) DF_ZERO_MEMORY(a, sizeof((a)[0]) * (n))

/* Simple logging function */

#ifndef DF_ENABLE_LOGGING
#define DF_ENABLE_LOGGING 1
#endif

enum
{
    df_log_level_verbose = 0,
    df_log_level_info = 1,
    df_log_level_warn = 2,
    df_log_level_error = 3,
};

#if DF_ENABLE_LOGGING

/** @brief The actual log implementation.
 *
 * There should be no need to call this directly.
 *
 * Instead use one of:
 * - df_log_verbose()
 * - df_log_info()
 * - df_log_warn()
 * - df_log_error()

 * @param level the log level. Used to filter the messages.
 * @param file file name of the log location
 * @param line line number of the log location
 * @param fmt format string of the message.
 */
void df_log_impl(int level, const char *file, int line, const char *fmt, ...);

#define df_log_verbose(...) df_log_impl(df_log_level_verbose, __FILE__, __LINE__, __VA_ARGS__)
#define df_log_info(...) df_log_impl(df_log_level_info, __FILE__, __LINE__, __VA_ARGS__)
#define df_log_warn(...) df_log_impl(df_log_level_warn, __FILE__, __LINE__, __VA_ARGS__)
#define df_log_error(...) df_log_impl(df_log_level_error, __FILE__, __LINE__, __VA_ARGS__)

#else /* DF_ENABLE_LOGGING = 0 */

#define df_log_verbose(fmt, ...)
#define df_log_info(fmt, ...)
#define df_log_warn(fmt, ...)
#define df_log_error(fmt, ...)

#endif

/* Basic types */

/** @brief RGBA color */
typedef union {
    struct
    {
        uint8_t r;
        uint8_t g;
        uint8_t b;
        uint8_t a;
    };
    uint8_t e[4];
} df_color;

/** @brief Linear interpolation between two colors.
 *
 * @param a first color
 * @param b second color
 * @param t interpolation factor
 * @return a + (b - a) * t
 */
df_color df_lerp_color(df_color a, df_color b, double t);

/** @brief 2d vector */
typedef union {
    struct
    {
        float x;
        float y;
    };
    struct
    {
        float u;
        float v;
    };
    float e[2];
} df_v2;

/** @brief 3d vector */
typedef union {
    struct
    {
        float x;
        float y;
        float z;
    };
    float e[3];
} df_v3;

/** @brief Add two 3d vectors */
df_v3 df_add_v3(df_v3 a, df_v3 b);

/** @brief Subtract two 3d vectors */
df_v3 df_sub_v3(df_v3 a, df_v3 b);

/** @brief Calculate the dot product of 3d vectors a and b.
 */
float df_dot_v3(df_v3 a, df_v3 b);

/** @brief Multiply a 3d vector with a scalar.
 */
df_v3 df_mul_v3(float t, df_v3 v);

/** @brief Returns the normalized version of a 3d vector v
 */
df_v3 df_normalize_v3(df_v3 v);

/** @brief A plane in 3d space.
 *
 * Expressed as the set of all points p for which
 * dot((p - base), normal) = 0
 */
typedef struct
{
    df_v3 base;
    df_v3 normal;
} df_plane;

/** @brief A line in 3d space.
 *
 * Expressed as the vector equation p = base + t * direction.
 */
typedef struct
{
    df_v3 base;
    df_v3 direction;
} df_line;

/** @brief The three possible result types of a line-plane intersection test.
 */
typedef enum
{
    /** The line and plane intersect in one point */
    df_line_plane_intersection_vector,

    /** The line is contained in the plane */
    df_line_plane_intersection_contained,

    /** The line and plane don't intersect (-> they are parallel) */
    df_line_plane_intersection_none,
} df_line_plane_intersection_type;

/** @brief Result of a line-plane intersection test.
 * The contained vector is only valid if @c type = @c df_line_plane_intersection_vector.
 */
typedef struct
{
    df_line_plane_intersection_type type;
    df_v3 vec;
} df_line_plane_intersection;

/** @brief Calculate the intersection between a line and a plane in 3d space */
df_line_plane_intersection df_calc_line_plane_intersection(df_line line, df_plane plane);

#endif