Question

我正在使用SDL2创建一个简单的基于平铺的游戏。我把瓷砖画在两层上。问题是第二层，你可以看到下面的图像由于某种原因，下面已经绘制的东西的瓷砖有一个偏红色调。例如，草的角落和侧面瓷砖应该是完全相同的颜色。

这是我的问题的图像：

这是我的瓷砖表：

这是我的代码：

#include <iostream>
#include <string>
#include <SDL.h>
#include <SDL_image.h>

//Screen dimension constants
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 640;
//The window we'll be rendering to
SDL_Window* window = NULL;
//The surface contained by the window
SDL_Surface* screenSurface = NULL;
//Holds built base layer of tilemap.
SDL_Surface* baseLayer = NULL;
//Map Data array
char mapLayerOne[20][20] = {
{4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4    },
{4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4    },
{4,4,4,6,6,6,6,6,6,4,4,4,4,4,4,4,4,4,4,4    },
{4,4,4,6,8,8,6,6,6,6,6,6,6,4,4,4,4,4,4,4    },
{4,4,4,6,8,8,6,6,6,6,6,6,6,4,4,4,4,4,4,4    },
{4,4,4,6,6,8,6,6,6,6,6,6,6,4,4,4,4,4,4,4    },
{4,4,4,6,6,8,8,8,8,6,6,6,6,6,4,4,4,4,4,4    },
{4,4,4,6,6,6,6,6,8,6,6,6,6,6,6,4,4,4,4,4    },
{4,4,4,6,6,14,6,6,8,8,6,6,6,6,6,4,4,4,4,4   },
{4,4,4,6,14,16,14,6,6,8,6,6,6,6,6,4,4,4,4,4 },
{4,4,4,14,16,16,16,12,8,8,8,8,6,6,6,4,4,4,4,4   },
{4,4,4,6,16,16,16,6,6,6,6,8,8,8,6,4,4,4,4,4 },
{4,4,4,6,6,16,6,6,6,6,6,6,6,8,6,4,4,4,4,4   },
{4,4,13,6,6,6,6,6,6,6,6,6,6,8,6,4,4,4,4,4   },
{4,4,4,14,14,14,14,14,14,14,14,14,14,14,14,15,4,4,4,4   },
{4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4    },
{4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4    },
{4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4    },
{4,4,4,4,4,4,4,4,4,4,4,4,6,6,6,6,4,4,4,4    },
{4,4,4,4,4,4,4,4,4,4,4,6,6,6,6,6,4,4,4,4    }
};
char mapLayerTwo[20][20] = {
{ 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 },
{ 0,0,1,2,2,2,2,2,3,0,0,0,0,0,0,0,0,0,0,0 },
{ 0,0,5,0,0,0,0,0,0,2,2,2,2,3,0,0,0,0,0,0 },
{ 0,0,5,0,0,0,0,0,0,0,0,0,0,7,0,0,0,0,0,0 },
{ 0,0,5,0,0,0,0,0,0,0,0,0,0,7,0,0,0,0,0,0 },
{ 0,0,5,0,0,0,0,0,0,0,0,0,0,7,0,0,0,0,0,0 },
{ 0,0,5,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0,0 },
{ 0,0,5,0,0,0,0,0,0,0,0,0,0,0,0,3,0,0,0,0 },
{ 0,0,5,0,0,10,0,0,0,0,0,0,0,0,0,7,0,0,0,0 },
{ 0,0,5,0,11,18,9,0,0,0,0,0,0,0,0,7,0,0,0,0 },
{ 0,0,5,7,19,0,12,12,0,0,0,0,0,0,0,7,0,0,0,0 },
{ 0,0,5,0,3,0,1,0,0,0,0,0,0,0,0,7,0,0,0,0 },
{ 0,0,5,0,0,2,0,0,0,0,0,0,0,0,0,7,0,0,0,0 },
{ 0,0,9,0,0,0,0,0,0,0,0,0,0,0,0,7,0,0,0,0 },
{ 0,0,17,9,10,10,10,10,10,10,10,10,10,12,10,11,0,0,0,0 },
{ 0,0,0,17,18,18,18,18,18,18,18,18,18,12,18,19,0,0,0,0 },
{ 0,0,0,0,0,0,0,0,0,0,0,0,0,12,0,0,0,0,0,0 },
{ 0,0,0,0,0,0,0,0,0,0,0,1,2,12,2,3,0,0,0,0 },
{ 0,0,0,0,0,0,0,0,0,0,0,5,0,8,0,0,3,0,0,0 },
{ 0,0,0,0,0,0,0,0,0,0,1,0,0,8,0,0,7,0,0,0 }
};
bool init();
void DrawTiles(SDL_Surface *image, char mapLayer);

int main(int argc, char* args[])
{
  //Main loop flag
  bool quit = false;
  //Event handler
  SDL_Event e;

  if(init())
  {
    //Load images
    SDL_Surface *image = IMG_Load("Images/TileSheet_01.png");
    if (!image)
    std::cout << "Failed to load TileSheet_01.png!" << std::endl;
    //Create BaseLayers of map
    DrawTiles(image, 1);
    DrawTiles(image, 2);

    //While application is running
    while (!quit)
    {
        //Handle events on queue
        while (SDL_PollEvent(&e) != 0)
        {
            //User requests quit
            if (e.type == SDL_QUIT)
                quit = true;
        }
        //Get window surface
        screenSurface = SDL_GetWindowSurface(window); 

        //Blit base layer of map to screenSurface
        SDL_BlitSurface(baseLayer, NULL, screenSurface, NULL);
        //Update the surface
        SDL_UpdateWindowSurface(window);
        //Delay in milliseconds to improve performance
        SDL_Delay(1);
    }
  }
  //Destroy window
  SDL_DestroyWindow(window);
  //Quit SDL subsystems
  SDL_Quit();
  return 0;
}

void DrawTiles(SDL_Surface *image, char mapLayer)
{
  SDL_Rect baseTile[20];
  int tileX = 0;
  int tileY = 0;
  for (int i = 1; i < 20; i++)
  {
    baseTile[i].h = 32;
    baseTile[i].w = 32;
    baseTile[i].x = tileX;
    baseTile[i].y = tileY;
    tileX += 32;
    if (tileX == 128) { tileY += 32; tileX = 0; }
  }
  //Fill the surface
  SDL_FillRect(screenSurface, NULL, SDL_MapRGB(screenSurface->format, 150, 50, 50));
  SDL_Rect tileLoc;
  tileLoc.x = 0;
  tileLoc.y = 0;
  // Draw tiles
  for (int i = 0; i < 20; i++)
  {
     for (int j = 0; j < 20; j++)
     {
        if (mapLayer == 1 && mapLayerOne[i][j] != 0)
            SDL_BlitSurface(image, &baseTile[mapLayerOne[i][j]], baseLayer, &tileLoc);
        else if (mapLayer == 2 && mapLayerTwo[i][j] != 0)
            SDL_BlitSurface(image, &baseTile[mapLayerTwo[i][j]], baseLayer, &tileLoc);
        tileLoc.x += 32;
        if (tileLoc.x == 640)
        {
            tileLoc.x = 0;
            tileLoc.y += 32;
        }
    }
  }
}

bool init()
{
  //Initialization flag
  bool success = true;

  //Initialize SDL
  if (SDL_Init(SDL_INIT_VIDEO) < 0)
  {
    std::cout << "SDL could not initialize!" << std::endl;
    success = false;
  }
  else
  {
    //Create window
    window = SDL_CreateWindow("My SDL TileMap", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN);
    if (window == NULL)
    {
        std::cout << "Window could not be created!" << std::endl;
        success = false;
    }
    else 
    {
        //Initialize PNG loading
        int imgFlags = IMG_INIT_PNG;
        if (!(IMG_Init(imgFlags) & imgFlags))
        {
            //std::cout << "SDL_image could not initialize!" << std::endl;
            printf("SDL_image could not initialize! SDL_image Error: %s\n", IMG_GetError());
            success = false;
        }
        else
        {
            //Get window surface
            screenSurface = SDL_GetWindowSurface(window);
            //Surface to hold baselayer of map.
            baseLayer = SDL_CreateRGBSurface(0, SCREEN_WIDTH, SCREEN_HEIGHT, 16, 0, 0, 0, 0);
        }
    }
}
SDL_Delay(300);
return success;
}

造成这种情况的原因是什么？

Answer 1

baseLayer = SDL_CreateRGBSurface( 0, SCREEN_WIDTH, SCREEN_HEIGHT, 16, 0, 0, 0, 0 );
                                                                  ^^ ...but you're using 32bpp PNGs

使用32位表面而不是16并填充蒙版：

    // https://wiki.libsdl.org/SDL_CreateRGBSurface#Code_Examples
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
    const Uint32 rmask = 0xff000000;
    const Uint32 gmask = 0x00ff0000;
    const Uint32 bmask = 0x0000ff00;
    const Uint32 amask = 0x000000ff;
#else
    const Uint32 rmask = 0x000000ff;
    const Uint32 gmask = 0x0000ff00;
    const Uint32 bmask = 0x00ff0000;
    const Uint32 amask = 0xff000000;
#endif
    baseLayer = SDL_CreateRGBSurface( 0, SCREEN_WIDTH, SCREEN_HEIGHT, 32, rmask, gmask, bmask, amask );

SDL2获得奇怪的颜色

1 个答案: