C++＆SDL纹理不会加载，但SDL_GetError（）不会返回任何东西

Question

当我发现真正奇怪的东西时，我在SDL2中玩耍。我试图绘制一个优化的纹理，但它不会工作。将表面转换为纹理的代码不起作用。根据文档，SDL_GetError（）应该给我错误，但它不会返回任何东西......任何帮助，将不胜感激！下面的代码：

Main.cpp的：

#include "SDLHelper.h" 
#include "Player.h" 

#define WIDTH 640 
#define HEIGHT 480 
#define NAME "TILES BOI!" 

int main(int args, char* argv[]){ 
    SDL_Window* gWindow; 
    SDL_Renderer* gRenderer; 
    if(!init(NAME, WIDTH, HEIGHT, &gWindow, &gRenderer)){ 
     printf("Failed to initialize!\n"); 
    }else{ 
      bool quit = false; 
      SDL_Event e; 
      Player* player = new Player(100, 100, 0, 0); 
      player->texture = loadTexture("sprites/people/male_walkcycle.png", &gRenderer); 
     while(!quit){ 
      while(SDL_PollEvent(&e) != 0){ 
       if(e.type == SDL_QUIT){ 
         quit = true; 
       } 
      } 

      SDL_RenderClear(gRenderer); 

      SDL_RenderCopy(gRenderer, player->texture, &(player->currentTexturePos), &(player->position)); 

      SDL_RenderPresent(gRenderer); 
     } 
     close(&gWindow, &gRenderer); 
    } 

    return 0; 
} 

SDLHelper.h：

#ifndef SDLHELPER_H 
    #define SDLHELPER_H 

    #include <SDL2/SDL.h> 
    #include <SDL2/SDL_image.h> 
    #include <stdio.h> 

    bool init(const char* name, int width, int height, SDL_Window** window, SDL_Renderer** renderer); 
    SDL_Texture* loadTexture(const char* path, SDL_Renderer** renderer); 
    void close(SDL_Window** gWindow, SDL_Renderer** gRenderer); 

    #endif 

SDLHelper.cpp：

#include "SDLHelper.h" 

bool init(const char* name, int width, int height, SDL_Window** window, SDL_Renderer** renderer){ 
    bool success = true; 
    if(SDL_Init(SDL_INIT_EVERYTHING) < 0){ 
     printf("SDL could not initialize! SDL Error: %s\n", SDL_GetError()); 
     success = false; 
    }else{ 
     if(!SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "1")){ 
      printf("Warning: Linear texture filtering is not enabled!\n"); 
     } 

     *window = SDL_CreateWindow(name, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, width, height, SDL_WINDOW_SHOWN); 
     if(*window == NULL){ 
      printf("Window could not be created! SDL Error: %s\n", SDL_GetError()); 
      success = false; 
     }else{ 
      *renderer = SDL_CreateRenderer(*window, -1, SDL_RENDERER_ACCELERATED); 
      if(*renderer == NULL){ 
       printf("Renderer could not be created! SDL Error: %s\n", SDL_GetError()); 
       success = false; 
      }else{ 
       SDL_SetRenderDrawColor(*renderer, 0xFF, 0xFF, 0xFF, 0xFF); 
       int imgFlags = IMG_INIT_PNG; 
       if(!(IMG_Init(imgFlags) & imgFlags)){ 
        printf("SDL_Image could not initialize! SDL_Image Error: %s\n",IMG_GetError()); 
        success = false; 
       } 
      } 
     } 
    } 
    return success; 
} 

SDL_Texture* loadTexture(const char* path, SDL_Renderer** renderer){ 
    SDL_Texture* newTexture = NULL; 
    SDL_Surface* loaded = IMG_Load(path); 
    if(loaded == NULL){ 
     printf("Unable to load image %s! SDL_Image Error: %s\n", path, IMG_GetError()); 
    }else{ 
     newTexture == SDL_CreateTextureFromSurface(*renderer, loaded); 
     if(newTexture == NULL){ 
      printf("Unable to create texture from %s! SDL Error: %s\n", path, SDL_GetError()); 
     } 
     SDL_FreeSurface(loaded); 
    } 

    return newTexture; 
} 

void close(SDL_Window** gWindow, SDL_Renderer** gRenderer){ 
    SDL_DestroyRenderer(*gRenderer); 
    SDL_DestroyWindow(*gWindow); 
    *gWindow = NULL; 
    *gRenderer = NULL; 

    //Quit SDL subsystems 
    IMG_Quit(); 
    SDL_Quit(); 
} 

Player.h：

#ifndef PLAYER_H 
#define PLAYER_H 

#include <SDL2/SDL.h> 

class Player 
{ 
public: 
    Player(int h, int m, int x, int y); 
    ~Player(); 
    SDL_Texture* texture; 
    SDL_Rect position; 
    SDL_Rect currentTexturePos; 
    int health; 
    int mana; 
    const char* name = "Bobby"; 
}; 
#endif 

Player.cpp：

#include "Player.h" 

Player::Player(int h, int m, int x, int y){ 
    health = h; 
    mana = m; 
    position.x = x; 
    position.y = y; 
    position.h = 64; 
    position.w = 64; 
    currentTexturePos.x = 64; 
    currentTexturePos.y = 0; 
    currentTexturePos.h = 64; 
    currentTexturePos.w = 64; 
} 

Player::~Player(){ 
    SDL_DestroyTexture(texture); 
    texture = NULL; 
} 

的Makefile：

CC = g++ 
FLAGS = -w -lSDL2 -lSDL2_image 
OBJECTS = main.cpp SDLHelper.cpp Player.cpp 
NAME = tileBasedRPG 

all: $(OBJECTS) 
    $(CC) $(OBJECTS) $(FLAGS) -o $(NAME) 

clean: 
    rm -rf *.o 

Answer 1

你永远不分配newTexture：

newTexture == SDL_CreateTextureFromSurface(*renderer, loaded); 

当它意味着是

newTexture = SDL_CreateTextureFromSurface(*renderer, loaded);