Episode 9

/*
Compile command:
g++ -o test main.cpp -lSDLmain -lSDL -lGL -lSDL_image
 */

// specific headers
#include "SDL/SDL.h"
#include "SDL/SDL_opengl.h"
#include "SDL/SDL_image.h"
#include <iostream>
#include <string>

//Function for loading an image into an texture
GLuint loadTexture( const std::string &fileName )
{
  SDL_Surface *image = IMG_Load( fileName.c_str() );

  SDL_DisplayFormatAlpha(image);

  unsigned object(0);

  glGenTextures(1, &object);

  glBindTexture(GL_TEXTURE_2D, object);

  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image->w, image->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, image->pixels);

  //Free surface
  SDL_FreeSurface(image);

  return object;
}

bool checkCollision(float Ax, float Ay, float Aw, float Ah, float Bx, float By, float Bw, float Bh) //Funcfion for checking collision
{
  if ( Ay+Ah < By ) return false; //if A is more to the left than B
  else if ( Ay > By+Bh ) return false; //if A is more to the right than B
  else if ( Ax+Aw < Bx ) return false; //if A is higher than B
  else if ( Ax > Bx+Bw ) return false; //if A is lower than B

  return true; //There is a collision because none of above returned false
}

struct Brick //Brick structures which holds 4 elements
{
  //Elements are used for x and y position of the brick and its width and height
  float x;
  float y;
  float width;
  float height;
  bool alive; //Alive variable. We use to to store in which state the brick is (broken, not broken)
};

//start of the program
int main( int argc, char* args[] )
{
  //initialize SDL
  SDL_Init(SDL_INIT_EVERYTHING);

  //Set OpenGL memory usage
  SDL_GL_SetAttribute( SDL_GL_RED_SIZE, 8 );
  SDL_GL_SetAttribute( SDL_GL_GREEN_SIZE, 8);
  SDL_GL_SetAttribute( SDL_GL_BLUE_SIZE, 8 );
  SDL_GL_SetAttribute( SDL_GL_ALPHA_SIZE, 8);
  SDL_GL_SetAttribute( SDL_GL_BUFFER_SIZE, 32);
  SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16 );
  SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 );

  //Caption of the window
  SDL_WM_SetCaption( "Our first game", NULL );

  //Size of the window
  SDL_SetVideoMode(600,400,32, SDL_OPENGL );

  //Specific the clear color
  glClearColor(1,1,1,1); //RED,GREEN,BLUE,ALPHA

  //What portion of the screen we will display
  glViewport(0,0,600,400);

  //Shader model - Use this
  glShadeModel(GL_SMOOTH);

  //2D rendering
  glMatrixMode(GL_PROJECTION);

  //"Save" it
  glLoadIdentity();

  //Disable depth checking
  glDisable(GL_DEPTH_TEST);

  //We enable blending of textures and set how we are going to blend it
  glEnable( GL_BLEND );
  glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);


  std::cout << "OpenGL is running\n";
  std::cout << "Main loop has started\n";

  //Handles the main loop
  bool isRunning = true;

  //For handling with event
  SDL_Event event;

  float myX = 300; //starting x position of rectangle
  float myY = 370; //starting y position of rectangle
  float width = 80; //width of the rectangle
  float height = 20; //height of the rectangle

  bool left = false,right = false; //we save in which state the button is

  //The ball variables
  float ballX = 50; //x position
  float ballY = 350; //y position
  float ballWH = 30; //width and height of the ball

  float vellX = 0.2; //x speed
  float vellY = -0.2; //y speed

  //Brick elements
  const static int BRICKS = 45; //Constant number where we define how many bricks we want

  Brick bricks[BRICKS]; //We create an array of bricks

  for ( int n = 0, x = 4, y = 10; n < BRICKS; n++, x+=66 ) //A for loop that goes throught the array so we can set the positions
    {
      if ( x > 560 ) //If x is near the right edge of the screen
    {
      x = 4; //We start going from the left again
      y += 25; //And move a down a little
    }
      bricks[n].x = x; //Set currents bricks x position
      bricks[n].y = y; //Y position
      bricks[n].width = 60; //Width
      bricks[n].height = 20; //Height
      bricks[n].alive = true; //Set alive to true (not broken)
    }

  //Create an texture
  unsigned int pad_texture = 0;
  //Load the image into the texture using the function
  pad_texture = loadTexture("test.png");

  //Main game loop
  while ( isRunning )
    {
      //EVENTS
      while ( SDL_PollEvent(&event) )
    {
      //if the window was closed
      if ( event.type == SDL_QUIT )
        {
          isRunning = false;
        }

      //If a button was released and the button is escape
      if ( event.type == SDL_KEYUP && event.key.keysym.sym == SDLK_ESCAPE )
        {
          isRunning = false;
        }

      if ( event.type == SDL_KEYUP && event.key.keysym.sym == SDLK_r )
        {
          glClearColor(1,0,0,1);
        }

      if ( event.type == SDL_KEYDOWN ) //Check for presed down buttons
        {
          if ( event.key.keysym.sym == SDLK_LEFT ) //Check left key
        {
          left = true; //Set the boolean value for left key to true (it is pressed)
        }

          else if ( event.key.keysym.sym == SDLK_RIGHT ) //Check Right key
        {
          right = true; //Set the boolean value for right key to true (it is pressed)
        }

        }

      else if ( event.type == SDL_KEYUP ) //Checking for released buttons
        {
          if ( event.key.keysym.sym == SDLK_LEFT ) //Left key
        {
          left = false; //Set the value to false (key is released)
        }

          else if ( event.key.keysym.sym == SDLK_RIGHT ) //Right key
        {
          right = false; //Key is released
        }
        }

      //logic that should happen for a certain event
    }

      //LOGIC
      if ( left == true ) //If left key is pressed
    {
      myX -= 0.5; //Move left
    }

      if ( right == true ) //If right key is pressed
    {
      myX += 0.5; //Move right
    }

      if ( myX < 0 ) //If the left border of the pad is over the left part of the screen
    {
      myX = 0; //Put the pad back so it isn't over the border
    }

      if ( myX+width > 600 ) //If the pad is over the right border of the screen
    {
      myX = 600-width; //Move it back so it only touches the right border
    }

      //The ball logic
      ballX += vellX; //Move the ball on x axis first

      for ( int n = 0; n < BRICKS; n++ ) //Go throught the array of bricks
    {
      if ( bricks[n].alive == true ) //If the bricks is alive
        {
          if ( checkCollision(ballX,ballY,ballWH,ballWH,bricks[n].x,bricks[n].y,bricks[n].width, bricks[n].height) == true ) //Check for collision with the ball
        {
          vellX = -vellX; //Change x velocity of the ball
          bricks[n].alive = false; //Set the alive variable to false (brick is broken)
          break; //Stop checking for collision on x axis
        }
        }
    }

      ballY += vellY; //move the ball on y axis second

      for ( int n = 0; n < BRICKS; n++ ) //Go throught the array of bricks
    {
      if ( bricks[n].alive == true ) //If the brick is alive
        {
          if ( checkCollision(ballX,ballY,ballWH,ballWH,bricks[n].x,bricks[n].y,bricks[n].width, bricks[n].height) == true ) //Check for collision
        {
          vellY = -vellY; //Change y velocity of the ball
          bricks[n].alive = false; //Set alive varible to false
          break; //Stop checking for collision on y axis
        }
        }
    }

      if ( ballX < 0 ) //Check if the ball hit the left edge of screen
    {
      vellX = -vellX; //negate the x velocity
    }

      else if ( ballX+ballWH>600 )
    {
      vellX = -vellX;
    }

      if ( ballY < 0 )
    {
      vellY = -vellY;
    }

      else if ( ballY+ballWH > 400 ) //if the ball hit the bottom edge of screen
    {
      //We set everything back as it was on the start, so we get a restart game impresion

      myX = 300; //starting x position of rectangle
      myY = 370; //starting y position of rectangle
      width = 80; //width of the rectangle
      height = 20; //height of the rectangle

      left = false,right = false; //Set the buttons back to false

      //The ball variables
      ballX = 50; //x position
      ballY = 350; //y position
      ballWH = 30; //width and height of the ball

      vellX = 0.2; //x speed
      vellY = -0.2; //y speed

      for ( int n = 0; n < BRICKS; n++ ) //A for loop that goes throught the array so we can set every bricks alive to true (not broken)
        {
          bricks[n].alive = true;
        }
    }

      if ( checkCollision(ballX,ballY,ballWH,ballWH,myX,myY,width,height) == true ) //if there is a collision between the ball and pad
    {
      vellY = -vellY; //change the ball's y velocity/speed
    }



      //RENDERING to the screen
      glClear(GL_COLOR_BUFFER_BIT);

      glPushMatrix(); //Start rendering phase

      glOrtho(0,600,400,0,-1,1); //Set the matrix

      glColor4ub(255,255,255,255); //White color

      //Enable textures when we are going to blend an texture
      glEnable(GL_TEXTURE_2D);
      //What texture we are going to use
      glBindTexture(GL_TEXTURE_2D,pad_texture);

      glBegin(GL_QUADS); //Start drawing the pad

      //We set the corners of the texture using glTexCoord2d
      glTexCoord2d(0,0); glVertex2f(myX,myY); //Upper-left corner
      glTexCoord2d(1,0); glVertex2f(myX+width,myY); //Upper-right corner
      glTexCoord2d(1,1); glVertex2f(myX+width,myY+height); //Down-right corner
      glTexCoord2d(0,1); glVertex2f(myX,myY+height); //Down-left corner

      glEnd(); //End drawing

      //Disable textures when we are done using them
      glDisable(GL_TEXTURE_2D);

      glColor4ub(255,0,0,255); //Red color

      glBegin(GL_QUADS); //Render of the ball, same method as for the pad
      glVertex2f(ballX,ballY);
      glVertex2f(ballX+ballWH,ballY);
      glVertex2f(ballX+ballWH,ballY+ballWH);
      glVertex2f(ballX,ballY+ballWH);
      glEnd();

      glColor4ub(0,0,255,255); //Blue color

      glBegin(GL_QUADS); //Render the bricks

      for ( int n = 0; n < BRICKS; n++ ) //We go throught all the elements (bricks)
    {
      if ( bricks[n].alive == true ) //We only draw the brick if it's alive
        {
          if ( n%2 == 0 ) glColor4ub(122,0,255,255); //Every 2nd bricks has a different color
          else glColor4ub(0,0,255,255); //Else it has normal blue color

          //The 4 edges of the current brick
          glVertex2f(bricks[n].x,bricks[n].y);
          glVertex2f(bricks[n].x+bricks[n].width,bricks[n].y);
          glVertex2f(bricks[n].x+bricks[n].width,bricks[n].y+bricks[n].height);
          glVertex2f(bricks[n].x,bricks[n].y+bricks[n].height);
        }
    }

      glEnd(); //End drawing

      glPopMatrix(); //End rendering phase

      SDL_GL_SwapBuffers();

      SDL_Delay(1); //Delay / pause
    }

  SDL_Quit();

  return 0;
}