partially done work on total source tree rework, separation of engine context and game context, generalization of renderer for different backends as well as web platform target

include/twn_util.h

@@ -0,0 +1,167 @@
+#ifndef UTIL_H
+#define UTIL_H
+
+#include "twn_vec.h"
+#include "twn_engine_api.h"
+
+#include <SDL2/SDL.h>
+#include <physfs.h>
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <math.h>
+#include <stdnoreturn.h>
+
+
+/*                   */
+/* GENERAL UTILITIES */
+/*                   */
+
+TWN_API void cry_impl(const char *file, const int line, const char *title, const char *text);
+#define CRY(title, text) cry_impl(__FILE__, __LINE__, title, text)
+#define CRY_SDL(title) cry_impl(__FILE__, __LINE__, title, SDL_GetError())
+#define CRY_PHYSFS(title)                                               \
+cry_impl(__FILE__, __LINE__, title, PHYSFS_getErrorByCode(PHYSFS_getLastErrorCode()))
+
+
+TWN_API void log_info(const char *restrict format, ...);
+TWN_API void log_critical(const char *restrict format, ...);
+TWN_API void log_warn(const char *restrict format, ...);
+
+
+/* for when there's absolutely no way to continue */
+TWN_API noreturn void die_abruptly(void);
+
+
+/* "critical" allocation functions which will log and abort() on failure. */
+/* if it is reasonable to handle this gracefully, use the standard versions. */
+/* the stb implementations will be configured to use these */
+TWN_API void *cmalloc(size_t size);
+TWN_API void *crealloc(void *ptr, size_t size);
+TWN_API void *ccalloc(size_t num, size_t size);
+
+
+/* DON'T FORGET ABOUT DOUBLE EVALUATION */
+/* YOU THINK YOU WON'T, AND THEN YOU DO */
+/* C23's typeof could fix it, so i will */
+/* leave them as macros to be replaced. */
+/* use the macro in tgmath.h for floats */
+#define MAX SDL_max
+#define MIN SDL_min
+
+#ifndef M_PI
+#define M_PI 3.14159265358979323846264338327950288   /**< pi */
+#endif
+
+/* multiply by these to convert degrees <---> radians */
+#define DEG2RAD (M_PI / 180)
+#define RAD2DEG (180 / M_PI)
+
+/* TODO: this is why generics were invented. sorry, i'm tired today */
+TWN_API double clamp(double d, double min, double max);
+TWN_API float clampf(float f, float min, float max);
+TWN_API int clampi(int i, int min, int max);
+
+/* sets buf_out to a pointer to a byte buffer which must be freed. */
+/* returns the size of this buffer. */
+TWN_API int64_t file_to_bytes(const char *path, unsigned char **buf_out);
+
+/* returns a pointer to a string which must be freed */
+TWN_API char *file_to_str(const char *path);
+
+
+/* returns true if str ends with suffix */
+TWN_API TWN_API bool strends(const char *str, const char *suffix);
+
+
+/*                      */
+/* GAME LOGIC UTILITIES */
+/*                      */
+
+/* 32-bit color data */
+typedef struct color {
+_Alignas(4)
+    uint8_t r;
+    uint8_t g;
+    uint8_t b;
+    uint8_t a;
+} t_color;
+
+
+/* a rectangle with the origin at the upper left (integer) */
+typedef struct rect {
+_Alignas(16)
+    int32_t x;
+    int32_t y;
+    int32_t w;
+    int32_t h;
+} t_rect;
+
+
+/* a rectangle with the origin at the upper left (floating point) */
+typedef struct frect {
+_Alignas(16)
+    float x;
+    float y;
+    float w;
+    float h;
+} t_frect;
+
+
+TWN_API bool intersect_rect(const t_rect *a, const t_rect *b, t_rect *result);
+
+TWN_API bool intersect_frect(const t_frect *a, const t_frect *b, t_frect *result);
+
+/* TODO: generics and specials (see m_to_fvec2() for an example)*/
+TWN_API t_frect to_frect(t_rect rect);
+
+TWN_API t_fvec2 frect_center(t_frect rect);
+
+
+typedef struct matrix4 {
+    t_fvec4 row[4];
+} t_matrix4;
+
+
+/* decrements an lvalue (which should be an int), stopping at 0 */
+/* meant for tick-based timers in game logic */
+/*
+ * example:
+ * tick_timer(&player->jump_air_timer);
+ */
+TWN_API void tick_timer(int *value);
+
+/* decrements a floating point second-based timer, stopping at 0.0 */
+/* meant for poll based real time logic in game logic */
+/* note that it should be decremented only on the next tick after its creation */
+TWN_API void tick_ftimer(float *value);
+
+/* same as `tick_ftimer` but instead of clamping it repeats */
+/* returns true if value was cycled */
+TWN_API bool repeat_ftimer(float *value, float at);
+
+/* http://www.azillionmonkeys.com/qed/sqroot.html */
+static inline float fast_sqrt(float x)
+{
+    union {
+        float f;
+        uint32_t u;
+    } pun = {.f = x};
+
+    pun.u += 127 << 23;
+    pun.u >>= 1;
+
+    return pun.f;
+}
+
+
+static inline t_fvec2 fast_cossine(float a) {
+    const float s = sinf(a);
+    return (t_fvec2){
+        .x = fast_sqrt(1.0f - s * s) * (a >= (float)M_PI_2 && a < (float)(M_PI + M_PI_2) ? -1 : 1),
+        .y = s
+    };
+}
+
+#endif