game.cpp

#include "Game.h"
#include <SDL.h>

const float paddleH = 100.0f;

Game::Game() 
	:mWindow(nullptr)
	,mRenderer(nullptr)
	,mIsRunning(true)
	
{
	mBallVel.x = -200.0f;
	mBallVel.y = 235.0f;
}

bool Game::Initialize()
{
	int sdlResult = SDL_Init(SDL_INIT_VIDEO);
	if (sdlResult != 0) {
		SDL_Log("Unable to initialize SDL: %s", SDL_GetError());
		return false;
	}

	mWindow = SDL_CreateWindow(
		"Game Programming in C++ (Chapter1)",
		100,
		100,
		1024,
		768,
		0
	);

	if (!mWindow)
	{
		SDL_Log("Failed to create window: %s", SDL_GetError());
		return false;
	}

	mRenderer = SDL_CreateRenderer(mWindow, -1, SDL_RENDERER_ACCELERATED|SDL_RENDERER_PRESENTVSYNC);
	if (!mRenderer) 
	{
		SDL_Log("Failed to create renderer: &s", SDL_GetError());
		return false;
	}

	mPaddlePos.x = 10.0f;
	mPaddlePos.y = 768.0f / 2.0f;

	mBallPos.x = 1024.0f / 2.0f;
	mBallPos.y = 768.0f / 2.0f;

	return true;
}

void Game::RunLoop()
{
	while (mIsRunning)
	{
		ProcessInput();
		UpdateGame();
		GenerateOutput();
	}
}

void Game::Shutdown()
{
	SDL_DestroyWindow(mWindow);
	SDL_DestroyRenderer(mRenderer);
	SDL_Quit();
}

Game::~Game()
{
}

void Game::ProcessInput()
{
	SDL_Event event;
	mPaddleDir = 0;
	while (SDL_PollEvent(&event))
	{
		switch (event.type)
		{
		case SDL_QUIT:
			mIsRunning = false;
			break;
		default:
			break;
		}
	}
	const Uint8* state = SDL_GetKeyboardState(NULL);
	if (state[SDL_SCANCODE_ESCAPE]) 
	{
		mIsRunning = false;
	}
	if (state[SDL_SCANCODE_W])
	{
		mPaddleDir -= 1;
	}
	if (state[SDL_SCANCODE_S])
	{
		mPaddleDir += 1;
	}

}

void Game::UpdateGame()
{
	while (!SDL_TICKS_PASSED(SDL_GetTicks(), mTicksCount + 16));

	float deltaTime = (SDL_GetTicks() - mTicksCount) / 1000.0f;

	if (deltaTime > 0.05f) {
		deltaTime = 0.05f;
	}

	if (mPaddleDir != 0) {
		mPaddlePos.y += mPaddleDir * 300.0f*deltaTime;
		if (mPaddlePos.y < paddleH / 2.0f + thickness) 
		{
			mPaddlePos.y = paddleH / 2.0f + thickness;
		}
		else if (mPaddlePos.y > (768.0f - paddleH / 2.0f - thickness)) 
		{
			mPaddlePos.y = 768.0f - paddleH / 2.0f - thickness;
		}
	}

	mBallPos.x += mBallVel.x * deltaTime;
	mBallPos.y += mBallVel.y * deltaTime;

	if (mBallPos.y <= thickness && mBallVel.y<0.0f)
	{
		mBallVel.y *= -1;
	}

	if(mBallPos.y >= 768 - thickness && mBallVel.y > 0.0f)
	{
		mBallVel.y *= -1;
	}

	if (mBallPos.x <= 0 && mBallVel.x < 0.0f)
	{
		mBallVel.x *= -1;
	}

	if (mBallPos.x >= 1024.0f - thickness && mBallVel.x > 0.0f)
	{
		mBallVel.x *= -1;
	}


	mTicksCount = SDL_GetTicks();
}

void Game::GenerateOutput()
{
	SDL_SetRenderDrawColor(mRenderer, 0, 0, 100, 255);

	SDL_RenderClear(mRenderer);

	SDL_SetRenderDrawColor(mRenderer, 255, 255, 255, 255);

	SDL_Rect wall{
		0,0,1024,thickness
	};
	SDL_RenderFillRect(mRenderer, &wall);

	wall.y = 768 - thickness;
	SDL_RenderFillRect(mRenderer, &wall);

	wall.x = 1024 - thickness;
	wall.y = 0;
	wall.w = thickness;
	wall.h = 1024;
	SDL_RenderFillRect(mRenderer, &wall);

	SDL_Rect paddle{
		static_cast<int>(mPaddlePos.x),
		static_cast<int>(mPaddlePos.y-paddleH/2),
		thickness,
		static_cast<int>(paddleH),
	};
	SDL_RenderFillRect(mRenderer, &paddle);

	SDL_Rect ball{
		static_cast<int>(mBallPos.x - thickness / 2),
		static_cast<int>(mBallPos.y - thickness / 2),
		thickness,
		thickness
	};

	SDL_RenderFillRect(mRenderer, &ball);


	SDL_RenderPresent(mRenderer);
}