SDL game dev support

[simplelenz]

Hey guys, I have been trying SDL 2.0 lately and I have decided to make a Tetris game as my 1st game.

I have coded to load a square and move around while it is moving vertically down as usually happens in Tetris game.

My problem is I don't know how to make a square appear on the screen after my 1st square reaches the bottom of the screen.

This is my code

#include <SDL.h>
#include <string>
#include <stdio.h>

SDL_Window *gameWindow = NULL; //game window
SDL_Texture *BGTexture = NULL; //SDL texture that holds the background
SDL_Texture *spriteTexture = NULL; // SDL texture that holds the game sprites
SDL_Renderer *gameRenderer = NULL; //game renderer
SDL_Event gameEvent; //main event

//SDL initializing function
bool Init()
{
    bool success = true;
    if (SDL_Init(SDL_INIT_VIDEO) < 0)
    {
        printf("SDL Initilizing error: ", SDL_GetError());
        success = false;
    }
    else
    {
        if (!SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "1"))
        {
            printf("Warning: Linear texture filtering not enabled!");
        }
        gameWindow = SDL_CreateWindow("Tetris", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 640, 480, SDL_WINDOW_SHOWN);
        if (gameWindow == NULL)
        {
            printf("Error in creating the game window: ", SDL_GetError());
            success = false;
        }
        else
        {
            gameRenderer = SDL_CreateRenderer(gameWindow, -1, SDL_RENDERER_ACCELERATED);
            if (gameRenderer == NULL)
            {
                printf("Error in creating the renderer: ", SDL_GetError());
                success = false;
            }
        }
    }
    return success;
}

//function that loads game sprites
bool loadMedia()
{
    bool success = true;
    SDL_Surface *imageSurf = SDL_LoadBMP("background.bmp");
    if (imageSurf == NULL)
    {
        printf("Error in loading the background", SDL_GetError());
        success = false;
    }
    else
    {
        BGTexture = SDL_CreateTextureFromSurface(gameRenderer, imageSurf);
        SDL_FreeSurface(imageSurf);
        if (BGTexture == NULL)
        {
            printf("Error in creating the background texture", SDL_GetError());
        }
    }

    imageSurf = SDL_LoadBMP("spritesheet.bmp");
    if (imageSurf == NULL)
    {
        printf("Error in loading the spritesheet", SDL_GetError());
        success = false;
    }
    else
    {
        spriteTexture = SDL_CreateTextureFromSurface(gameRenderer, imageSurf);
        SDL_FreeSurface(imageSurf);
        if (spriteTexture == NULL)
        {
            printf("Error in creating the sprite texture", SDL_GetError());
        }
    }
    return success;
}

//function that frees the memory which has been allocated by each SDL structures
void Close()
{
    SDL_DestroyTexture(BGTexture);
    SDL_DestroyTexture(spriteTexture);
    SDL_DestroyRenderer(gameRenderer);
    SDL_DestroyWindow(gameWindow);
    SDL_Quit();
}

//Square class for the game squares
class TSquare
{
private:
    // x, y, co-ordinates of the square
    int Xpos, Ypos;

public:
    //Square class constructor
    TSquare();
    //function that handles the user inputs to square objects
    void Input_handle();
    //function that moves the square
    void Move();
    //function that displays the square to the screen
    void Display();
};

TSquare::TSquare()
{
    Xpos = 0;
    Ypos = 0;
}

void TSquare::Input_handle()
{
    if (gameEvent.type == SDL_KEYDOWN)
    {
        switch(gameEvent.key.keysym.sym)
        {
            case SDLK_UP: Ypos -= 25; break;
            case SDLK_DOWN: Ypos += 25; break;
            case SDLK_LEFT: Xpos -= 25; break;
            case SDLK_RIGHT: Xpos += 25; break;
        }
    }
    else if (gameEvent.type == SDL_KEYUP)
    {
            switch(gameEvent.key.keysym.sym)
        {
            case SDLK_UP: Ypos += 0; break;
            case SDLK_DOWN: Ypos -= 0; break;
            case SDLK_LEFT: Xpos += 0; break;
            case SDLK_RIGHT: Xpos -= 0; break;
        }
    }
}

void TSquare::Move()
{
    Ypos += 1;
    //if the square moves to the bottom of the screen, the square will stop
    if (Ypos >= 450)
    {
        Ypos -= 1;
    }
}

void TSquare::Display()
{
    SDL_Rect SrcRect[3]; //rectangles for 4 square sprites
    SDL_Rect DestRect; //sprite rectangle that will be displayed

    SrcRect[0].x = 0;
    SrcRect[0].y = 0;
    SrcRect[0].w = 100;
    SrcRect[0].h = 100;

    SrcRect[1].x = 100;
    SrcRect[1].y = 0;
    SrcRect[1].w = 200;
    SrcRect[1].h = 100;

    SrcRect[2].x = 0;
    SrcRect[2].y = 100;
    SrcRect[2].w = 100;
    SrcRect[2].h = 200;

    SrcRect[3].x = 100;
    SrcRect[3].y = 100;
    SrcRect[3].w = 200;
    SrcRect[3].h = 200;

    DestRect.x = Xpos;
    DestRect.y = Ypos;
    DestRect.w = 25;
    DestRect.h = 25;

    SDL_RenderCopy(gameRenderer, spriteTexture, &SrcRect[1], &DestRect);
}

int main(int argc, char *args[])
 {
    //variable that holds the sdl ticks
    Uint32 loopStart = 0;

    Init();
    loadMedia();

    //1st object square in the game
    TSquare gameSquare;

    bool quit = false;
    while(!quit)
    {
        loopStart = SDL_GetTicks();

        while(SDL_PollEvent(&gameEvent))
        {
            gameSquare.Input_handle();

            if (gameEvent.type == SDL_QUIT)
            {
                quit = true;
            }
        }

        gameSquare.Move();

        SDL_RenderClear(gameRenderer);
        SDL_RenderCopy(gameRenderer, BGTexture, NULL, NULL);

        gameSquare.Display();

        SDL_RenderPresent(gameRenderer);

        //if the time difference at the end of the loop and the begining of
        //the loop is smaller than the time takes to run 60 frames,
        //the remaining time will be dlayed
        if ((SDL_GetTicks() - loopStart) < (1000/60))
        {
            SDL_Delay((1000/60) - (SDL_GetTicks() - loopStart));
        }
    }

    Close();

    return 0;
}