C++ SDL2/Scrolling Collision Issue

Question

タイトルが示唆するように、私はスクロールとの衝突を実装しようとしています。 ここのコードは最上位ではなく、オブジェクト指向プログラミングを利用していません。しかし、このコードは、私がそのゲームで再利用できるように、私が作っているゲームの衝突のプロトタイプです。 とにかく、このコードを書いてスクロールを実装しなかったとき、衝突は正常に機能しました。しかし、私がスクロールを実装すると、突然、プレーヤーを表す矩形の1ピクセルが、私が衝突をテストするために使用した長方形に突き当たりました。

ここにコードがあります。

MAIN.CPP：

#include "SDL.h" 
#include "SDL_image.h" 
#include "SDL_mixer.h" 
#include "SDL_ttf.h" 
using namespace std; 

int main(int argc, char *argv[]) { 

    SDL_Init(SDL_INIT_EVERYTHING); 
    IMG_Init(IMG_INIT_PNG | IMG_INIT_JPG); 
    Mix_Init(MIX_INIT_MP3); 
    Mix_OpenAudio(MIX_DEFAULT_FREQUENCY, MIX_DEFAULT_FORMAT, 2, 640); 
    TTF_Init(); 

    SDL_Window *Window = SDL_CreateWindow("Test", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1000, 600, SDL_WINDOW_SHOWN); 
    SDL_Renderer *Renderer = SDL_CreateRenderer(Window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC); 

    bool quit = false; 
    SDL_Event Event; 

    SDL_Rect Box; 
    Box.w = 25; 
    Box.h = 25; 
    Box.x = 500 - int(Box.w/2); 
    Box.y = 300 - int(Box.h/2); 

    int CAMERA_X = 0; 
    int CAMERA_Y = 0; 

    int xVel = 0; 
    int yVel = 0; 

    SDL_Rect RECTS[3]; 
    RECTS[0].x = 50; 
    RECTS[0].y = 50; 
    RECTS[0].w = 50; 
    RECTS[0].h = 100; 
    RECTS[1].x = 150; 
    RECTS[1].y = 50; 
    RECTS[1].w = 50; 
    RECTS[1].h = 100; 
    RECTS[2].x = 250; 
    RECTS[2].y = 50; 
    RECTS[2].w = 50; 
    RECTS[2].h = 100; 

    SDL_Rect CAM_RECTS[3]; 
    CAM_RECTS[0].x = 50; 
    CAM_RECTS[0].y = 50; 
    CAM_RECTS[0].w = 50; 
    CAM_RECTS[0].h = 100; 
    CAM_RECTS[1].x = 150; 
    CAM_RECTS[1].y = 50; 
    CAM_RECTS[1].w = 50; 
    CAM_RECTS[1].h = 100; 
    CAM_RECTS[2].x = 250; 
    CAM_RECTS[2].y = 50; 
    CAM_RECTS[2].w = 50; 
    CAM_RECTS[2].h = 100; 

    const Uint8 *Input = NULL; 

    while (!quit) { 

     Input = SDL_GetKeyboardState(NULL); 

     while (SDL_PollEvent(&Event)) { 

      if (Event.type == SDL_QUIT) { 

       quit = true; 

      } 

     } 

     if (Input[SDL_SCANCODE_RIGHT]) { 

      xVel = -7; 

     } else if (Input[SDL_SCANCODE_LEFT]) { 

      xVel = 7; 

     } else { 

      xVel = 0; 

     } 

     if (Input[SDL_SCANCODE_UP]) { 

      yVel = 7; 

     } else if (Input[SDL_SCANCODE_DOWN]) { 

      yVel = -7; 

     } else { 

      yVel = 0; 

     } 

     for (unsigned int i = 0; i < 3; i++) { 

      CAM_RECTS[i].x = RECTS[i].x + CAMERA_X; 
      CAM_RECTS[i].y = RECTS[i].y + CAMERA_Y; 

     } 

     CAMERA_X += xVel; 

     for (unsigned int i = 0; i < 3; i++) { 

      if (Box.x <= CAM_RECTS[i].x + CAM_RECTS[i].w && Box.x + Box.w >= CAM_RECTS[i].x && Box.y <= CAM_RECTS[i].y + CAM_RECTS[i].h && Box.y + Box.h >= CAM_RECTS[i].y) { 

       if (Box.x <= CAM_RECTS[i].x + CAM_RECTS[i].w && Box.x + Box.w >= CAM_RECTS[i].x) { 

        CAMERA_X += -xVel; 

       } 

      } 

     } 

     CAMERA_Y += yVel; 

     for (unsigned int i = 0; i < 3; i++) { 

      if (Box.x <= CAM_RECTS[i].x + CAM_RECTS[i].w && Box.x + Box.w >= CAM_RECTS[i].x && Box.y <= CAM_RECTS[i].y + CAM_RECTS[i].h && Box.y + Box.h >= CAM_RECTS[i].y) { 

       if (Box.y <= CAM_RECTS[i].y + CAM_RECTS[i].h && Box.y + Box.h >= CAM_RECTS[i].y) { 

        CAMERA_Y += -yVel; 

       } 

      } 

     } 

     SDL_SetRenderDrawColor(Renderer, 0, 0, 0, 255); 
     SDL_RenderClear(Renderer); 

     SDL_SetRenderDrawColor(Renderer, 255, 255, 255, 255); 
     SDL_RenderFillRect(Renderer, &Box); 

     SDL_SetRenderDrawColor(Renderer, 255, 255, 255, 255); 

     for (unsigned int i = 0; i < 3; i++) { 

      SDL_RenderFillRect(Renderer, &CAM_RECTS[i]); 

     } 

     SDL_RenderPresent(Renderer); 

    } 

    Input = NULL; 

    SDL_DestroyRenderer(Renderer); 
    SDL_DestroyWindow(Window); 

    TTF_Quit(); 
    Mix_CloseAudio(); 
    Mix_Quit(); 
    IMG_Quit(); 
    SDL_Quit(); 

    return 0; 

} 

助けてください。 ありがとうありがとうございました:)

Answer 1

私は答えを変更しました。今はジッタなく動作するはずです。

これは間違いなく最適な解決策ではありませんが、プログラムのより広い概念に左右されます。

int sign(int x) 
{ 
    return (x > 0) - (x < 0); 
} 

/* Movement values are updated by referenced arguments.*/ 
void check_collisions(SDL_Rect* obj_rects, unsigned num_of_obj, 
     SDL_Rect obstacle, int& horizontal_move, int& vertical_move) 
{ 
    for (unsigned int i = 0; i < num_of_obj; i++) 
    { 

     int obj_new_x = obj_rects[i].x + horizontal_move; 

     // Horizontal collision 
     if (obj_new_x < (obstacle.x + obstacle.w) 
      && (obj_new_x + obj_rects[i].w) > obstacle.x 
      && obj_rects[i].y < (obstacle.y + obstacle.h) 
      && (obj_rects[i].h + obj_rects[i].y) > obstacle.y) 
     { 
      // Calculate maximal possible horizontal movement. 
      if (sign(horizontal_move) == 1) 
       horizontal_move = obstacle.x - (obj_rects[i].x + obj_rects[i].w); 
      else if (sign(horizontal_move) == -1) 
       horizontal_move = (obstacle.x + obstacle.w) - obj_rects[i].x; 
     } 

     int obj_new_y = obj_rects[i].y + vertical_move; 

     // Vertical collision 
     if (obj_rects[i].x < (obstacle.x + obstacle.w) 
      && (obj_rects[i].x + obj_rects[i].w) > obstacle.x 
      && obj_new_y < (obstacle.y + obstacle.h) 
      && (obj_new_y + obj_rects[i].h) > obstacle.y) 
     { 
      if (sign(vertical_move) == 1) 
       vertical_move = obstacle.y - (obj_rects[i].y + obj_rects[i].h); 
      else if (sign(vertical_move) == -1) 
       vertical_move = (obstacle.y + obstacle.h) - obj_rects[i].y; 
     } 
    } 
} 

int cam_velocity = 5; 
... 

while (!quit) { 
... 
    if (Input[SDL_SCANCODE_RIGHT]) 
    { 
     x_movement = cam_velocity; 
    } 
    else if (Input[SDL_SCANCODE_LEFT]) 
    { 
     x_movement = -cam_velocity; 
    } 

    if (Input[SDL_SCANCODE_UP]) 
    { 
     y_movement = -cam_velocity; 
    } 
    else if (Input[SDL_SCANCODE_DOWN]) 
    { 
     y_movement = cam_velocity; 
    } 

    check_collisions(CAM_RECTS, 3, Box, x_movement, y_movement); 

    CAMERA_X += x_movement; 
    CAMERA_Y += y_movement; 

    for (unsigned int i = 0; i < 3; i++) { 

     CAM_RECTS[i].x = RECTS[i].x + CAMERA_X; 
     CAM_RECTS[i].y = RECTS[i].y + CAMERA_Y; 
    } 
...