Question

我不断地重新定义默认参数参数1错误，并且由于我将其包含在内，它无法成功构建项目以测试代码。对于C ++和这种构建游戏的形式，我相对较新，具有多个互相引用的标头和cpp文件。

Texture2D.cpp：

#include <iostream>
#include <SDL_image.h>
#include <string>
#include "Texture2D.h"
#include "Constants.h"
#include "Commons.h"
using namespace::std;


Texture2D::Texture2D(SDL_Renderer* renderer)
{
    SDL_Renderer*   mRenderer   = NULL;
    SDL_Texture*    mTexture    = NULL;
    mWidth                  = 0;
    mHeight                 = 0;
}

Texture2D::~Texture2D()
{
    Free();
    mRenderer = NULL;
}

bool Texture2D::LoadFromFile(string path)
{
    //remove the memory used for a previous texture
    Free();
    SDL_Texture* mTexture = NULL;

    //load the image
    SDL_Surface* pSurface = IMG_Load(path.c_str());

    mWidth  = pSurface->w;
    mHeight = pSurface->h;

    if (pSurface != NULL)
    {
        mTexture = SDL_CreateTextureFromSurface(mRenderer, pSurface);

        if (mTexture == NULL)
        {
            cout << "Unable to create texture from surface. Error: " << SDL_GetError() << endl;
        }

        //Color key the image - The color to be transparent
        SDL_SetColorKey(pSurface, SDL_TRUE, SDL_MapRGB(pSurface->format, 0, 0xFF, 0xFF));

        SDL_FreeSurface(pSurface);
        return mTexture;
    }

    else
    {
        cout << "Unable to create texture from surface. Error: " << IMG_GetError() << endl;
    }
}

void Texture2D::Render(Vector2D newPosition, SDL_RendererFlip flip, double angle = 0.0f)
{
    //clear the screen
    SDL_SetRenderDrawColor(mRenderer, 0xFF, 0xFF, 0xFF, 0xFF);
    SDL_RenderClear(mRenderer);

    //set where to render the texture
    SDL_Rect renderLocation = { 0, 0, mWidth, mHeight };

    //render to screen
    SDL_RenderCopyEx(mRenderer, mTexture, NULL, &renderLocation, 0, NULL, SDL_FLIP_NONE);
    SDL_RenderPresent(mRenderer);
}

void Texture2D::Free()
{
    if (mTexture != NULL)
    {
        SDL_DestroyTexture(mTexture);
        mTexture =  NULL;
        mWidth =    0;
        mHeight =   0;
    }
}

Texture2D.h：

#pragma once

#ifndef _TEXTURE2D_H
#define _TEXTURE2D_H
#include <SDL.h>
#include <SDL_image.h>
#include <map>
#include <string>
#include "Commons.h"

class Texture2D
{

public:
    Texture2D(SDL_Renderer* renderer);
    ~Texture2D();

    bool LoadFromFile(std::string path);
    void Free();
    void Render(Vector2D newPosition, SDL_RendererFlip flip, double angle = 0.0f);

    int GetWidth()  { return mWidth; }
    int GetHeight() { return mHeight; }

private:
    SDL_Renderer*   mRenderer;
    SDL_Texture*    mTexture;

    int             mWidth;
    int             mHeight;
};


#endif //_TEXTURE2D_H

Commons.h：

#pragma once
#ifndef _COMMONS_H
#define _COMMONS_H

struct Vector2D
{
    Vector2D()
    {
        x = 0.0f;
        y = 0.0f;
    }

    float x;
    float y;
};

struct InitialVector2D
{
    InitialVector2D()
    {
        initialx = 0.0f;
        initialy = 0.0f;
    }

    float initialx;
    float initialy;
};

enum SCREENS
{
    SCREEN_INTRO = 0,
    SCREEN_MENU,
    SCREEN_LEVEL1,
    SCREEN_LEVEL2,
    SCREEN_GAMEOVER,
    SCREEN_HIGHSCORES
};    
#endif //_COMMONS_H

Answer 1

只需在此处删除默认规范即可：void Texture2D :: Render（Vector2D newPosition，SDL_RendererFlip flip，double angle = 0.0f）正如编译器告诉您的那样，该声明已在函数声明中给出。 – 47分钟前πάνταῥεῖ

Answer 2

提供默认参数时，应仅在标题声明中添加默认参数。因此，更改：

void Texture2D::Render(Vector2D newPosition, SDL_RendererFlip flip, double angle = 0.0f)

收件人：

void Texture2D::Render(Vector2D newPosition, SDL_RendererFlip flip, double angle)

应纠正该错误。

C ++重定义默认参数：参数1（Vector2D）

2 个答案: