Hi I'm working on the book SDL Game Development by Shaun Mitchell trying to build his game engine for my own use. I am a c++ and sdl noob, I had problems getting the include statements right for this section of the book but I managed to get an executable in the end by making my object files first then linking them together with g++ e.g g++ -c main.cpp, g++ Game.cpp, g++ TextureManager.cpp then g++ TextureManager.o Game.o main.o to get my executable, I managed to run it and it shows a dog in the top left over a red background, the only thing is the dog is supposed to be animated as a running dog. Can anybody explain to me what I have done wrong in the coding or the linking/compilation process that stops the dog moving? Thanks.
main.cpp
#include "Game.h"
//our game object
Game* g_game = 0;
int main(int argc, char* argv[])
{
g_game = new Game(); // on the freestore
g_game->init("Chapter 1",100,100,640,480,SDL_WINDOW_SHOWN);
//game loop
while(g_game->running())
{
g_game->handleEvents();
g_game->update();
g_game->render();
}
g_game->clean();
return 0;
}Game.h
#ifndef __Game__
#define __Game__
#include "TextureManager.h"
#include<SDL2/SDL.h>
#include<SDL2/SDL_image.h>
class Game
{
public:
Game() {}
~Game() {}
// init function passed to SDL_CreateWindow
bool init(const char* title, int xpos, int ypos, int width,
int height, int flags);
void render();
void update();
void handleEvents();
void clean();
// a function to access the private running variable
bool running() { return m_bRunning; }
private:
SDL_Window* m_pWindow = 0;
SDL_Renderer* m_pRenderer = 0;
SDL_Texture* m_pTexture= 0; // the new SDL_Texture variable
//SDL_Rect m_sourceRectangle; // the first rectangle
//SDL_Rect m_destinationRectangle; // another rectangle
bool m_bRunning;
int m_currentFrame;
TextureManager m_textureManager;
};
#endif /* defined(__Game__) */
Game.cpp
#include <iostream>
#include "Game.h"
bool Game::init(const char* title, int xpos, int ypos, int width,
int height, int flags)
{
m_bRunning = true;
//attempt to initialize SDL
if(SDL_Init(SDL_INIT_EVERYTHING) == 0)
{
std::cout<<"SDL init sucess\n";
//init the window
m_pWindow = SDL_CreateWindow(title, xpos, ypos,
width, height, flags);
if(m_pWindow !=0) // window init success
{
std::cout << "window creation success\n";
m_pRenderer = SDL_CreateRenderer(m_pWindow, -1, 0);
if(m_pRenderer !=0) // renderer init success
{
std::cout << "renderer creation success\n";
SDL_SetRenderDrawColor(m_pRenderer,
255,0,0,255);
}
else
{
std::cout<<"renderer init fail\n";
return false; // renderer init fail
}
}
else
{
std::cout <<"window init fail\n";
return false; // window init fail
}
}
else
{
std::cout<<"SDL init fail\n";
return false; // SDL init fail
}
std::cout <<"init success\n";
m_bRunning= true; // everything inited successfully,
//start the main loop
m_textureManager.load("assets/animate-alpha.png","animate",
m_pRenderer);
//SDL_Surface* pTempSurface = IMG_Load("assets/animate-alpha.png");
//m_pTexture = SDL_CreateTextureFromSurface(m_pRenderer, pTempSurface);
//SDL_FreeSurface(pTempSurface);
//SDL_QueryTexture(m_pTexture, NULL, NULL,
//&m_sourceRectangle.w, &m_sourceRectangle.h);
//m_destinationRectangle.x = m_sourceRectangle.x = 0;
//m_destinationRectangle.y = m_sourceRectangle.y = 0;
//m_destinationRectangle.w = 128;
//m_destinationRectangle.h = 82;
//m_sourceRectangle.w = 128;
//m_sourceRectangle.h = 82;
//m_sourceRectangle.x = 0;
//m_sourceRectangle.y = 0;
//m_destinationRectangle.x = 0;
//m_destinationRectangle.y = 0;
return true;
}
void Game::render()
{
SDL_RenderClear(m_pRenderer); // clear the renderer to the
// draw color
m_textureManager.draw("animate", 0,0,128,82, m_pRenderer);
m_textureManager.drawFrame("animate",100,100,128,82,
1, m_currentFrame, m_pRenderer);
//SDL_RenderCopy(m_pRenderer, m_pTexture, &m_sourceRectangle,
//&m_destinationRectangle);
SDL_RenderPresent(m_pRenderer); // draw to the screen
}
void Game::update()
{
m_currentFrame = int(((SDL_GetTicks() / 100) % 6));
}
void Game::handleEvents()
{
SDL_Event event;
if(SDL_PollEvent(&event))
{
switch (event.type)
{
case SDL_QUIT:
m_bRunning = false;
break;
default:
break;
}
}
}
void Game::clean()
{
std::cout<<"cleaning game\n";
SDL_DestroyWindow(m_pWindow);
SDL_DestroyRenderer(m_pRenderer);
SDL_Quit();
}TextureManager.h
#ifndef __TextureManager__
#define __TextureManager__
#include<map>
#include<string>
#include<SDL2/SDL.h>
class TextureManager
{
public:
bool load(std::string filename, std::string id,
SDL_Renderer* pRenderer);
//draw
void draw(std::string id, int x, int y, int width, int
height, SDL_Renderer* pRenderer, SDL_RendererFlip flip =
SDL_FLIP_NONE);
//draw function
void drawFrame(std::string id, int x, int y, int width, int
height, int currentRow, int currentFrame, SDL_Renderer*
pRenderer, SDL_RendererFlip flip= SDL_FLIP_NONE);
std::map<std::string, SDL_Texture*> m_textureMap;
private:
};
#endif /* defined(__TextureManager__) */TextureManager.cpp
#include "TextureManager.h"
#include<SDL2/SDL_image.h>
bool TextureManager::load(std::string fileName, std::string
id, SDL_Renderer* pRenderer)
{
SDL_Surface* pTempSurface = IMG_Load(fileName.c_str());
if(pTempSurface == 0)
{
return false;
}
SDL_Texture* pTexture =
SDL_CreateTextureFromSurface(pRenderer, pTempSurface);
SDL_FreeSurface(pTempSurface);
// everything went ok, add the texture to our list
if(pTexture != 0)
{
m_textureMap[id] = pTexture;
return true;
}
// reaching here means something went wrong
return false;
}
void TextureManager::draw(std::string id, int x, int y,
int width, int height, SDL_Renderer* pRenderer, SDL_RendererFlip flip)
{
SDL_Rect srcRect;
SDL_Rect destRect;
srcRect.x = 0;
srcRect.y = 0;
srcRect.w = destRect.w = width;
srcRect.h = destRect.h = height;
destRect.x = x;
destRect.y = y;
SDL_RenderCopyEx(pRenderer, m_textureMap[id], &srcRect,
&destRect, 0, 0, flip);
}
void TextureManager::drawFrame(std::string id, int x, int y,
int width, int height, int currentRow, int currentFrame,
SDL_Renderer *pRenderer, SDL_RendererFlip flip)
{
SDL_Rect srcRect;
SDL_Rect destRect;
srcRect.x = width * currentFrame;
srcRect.y = height * currentRow -1;
srcRect.w = destRect.w = width;
srcRect.h = destRect.h = height;
destRect.x = x;
destRect.y = y;
SDL_RenderCopyEx(pRenderer, m_textureMap[id], &srcRect,
&destRect, 0, 0, flip);
}
