Я пишу игровой движок в C с SDL2, и я пытаюсь использовать бит twiddling для хранения моего текущего направления движения.
Я не совсем уверен, как воспроизвести его, но вот видео показывает ошибку:
https://youtu.be/RnPZaUDPElUПочему игрок иногда двигается в неправильном направлении при переключении направления
А вот проблемный код:
#define BMXSPEED 0x01
#define BMYSPEED 0x04
void BEvent (btree_t *t) {
SDL_Event event;
while (SDL_PollEvent(&event)) {
switch (event.type) {
case SDL_QUIT:
t->run = 0;
break;
case SDL_KEYDOWN:
switch (event.key.keysym.scancode) {
case SDL_SCANCODE_ESCAPE:
t->run = 0;
break;
case SDL_SCANCODE_D:
if (!event.key.repeat) {
t->player->speed |= BMXSPEED;
}
break;
case SDL_SCANCODE_A:
if (!event.key.repeat) {
t->player->speed |= (BMXSPEED << 1);
}
break;
case SDL_SCANCODE_S:
if (!event.key.repeat) {
t->player->speed |= BMYSPEED;
}
break;
case SDL_SCANCODE_W:
if (!event.key.repeat) {
t->player->speed |= (BMYSPEED << 1);
}
break;
}
break;
case SDL_KEYUP:
switch (event.key.keysym.scancode) {
case SDL_SCANCODE_D:
t->player->speed &= ~BMXSPEED;
break;
case SDL_SCANCODE_A:
t->player->speed &= ~(BMXSPEED << 1);
break;
case SDL_SCANCODE_S:
t->player->speed &= ~BMYSPEED;
break;
case SDL_SCANCODE_W:
t->player->speed &= ~(BMYSPEED << 1);
break;
}
break;
}
}
/* X movement */
if (t->player->speed & BMXSPEED && (t->player->speed & (BMXSPEED << 1)) != (BMXSPEED << 1))
t->player->xspeed += (t->player->xspeedMax - abs(t->player->xspeed))/t->player->xspeedMax;
else
if (t->player->speed & (BMXSPEED << 1) && (t->player->speed & BMXSPEED) != BMXSPEED)
t->player->xspeed -= (t->player->xspeedMax - abs(t->player->xspeed))/t->player->xspeedMax;
else
t->player->xspeed += (t->player->xspeedMin - t->player->xspeed)/t->player->xspeedMax;
/* Y movement */
if (t->player->speed & BMYSPEED && (t->player->speed & (BMYSPEED << 1)) != (BMYSPEED << 1))
t->player->yspeed += (t->player->yspeedMax - abs(t->player->yspeed))/t->player->yspeedMax;
else
if (t->player->speed & (BMYSPEED << 1) && (t->player->speed & BMYSPEED) != BMYSPEED)
t->player->yspeed -= (t->player->yspeedMax - abs(t->player->yspeed))/t->player->yspeedMax;
else
t->player->yspeed += (t->player->yspeedMin - t->player->yspeed)/t->player->yspeedMax;
t->player->rect.x += (int)t->player->xspeed;
t->player->rect.y += (int)t->player->yspeed;
}
EDIT: После изменения метода направления хранения, я определил, что проблема не связана с сверлением бит. Я подозреваю, что это метод ускорения.
что об использовании отладчика ?? –