Conway's Game of life

We have a few objectives to accomplish with the tutorial:

- Use Code::Blocks to create projects, add classes, configure libraries, etc.
- Setting up SDL with Code::Blocks
- Creating a simplistic game engine.
- Loading and displaying a image tile set on the screen.
- Basic use of mouse, keyboard, timing.

Our prerequisite for the tutorial is a simple tile set image:

I have made it using Gimp, we have 5 different tiles, from left to right: empty cell, living cell, new born cell, death cell and the mouse cursor.

Conway's Game of Life is a simulation of "living" cells, let's suppose our world is a big 2D grid, now let's suppose again that each cell in the grid can have 4 different states :

- 0 > Empty cell , a void in the map.
- 1 > A living cell.
- 2 > A new born cell.
- 3 > A dying cell.

//We need a grid to store data, we have a map of 50 x 50 cells Uint8 CellMap[50][50]; // A temporary counter of surrounding cells Uint8 counter; // Variables used when working with the 2d array "CellMap" Uint8 x,y; //Now let's initialize the array, it's always a very good idea to initialize variables to prevent unexpected results in the program. for (x=0;x<50;x++){ for (y=0;y<50;y++){ CellMap[x][y]=0; //We will start with an empty map }; //end y for }; // end x for //We will start with just 5 living cells in a configuration called "slider" CellMap[1][5]=1; CellMap[2][5]=1; CellMap[3][5]=1; CellMap[3][4]=1; CellMap[2][3]=1; // program main loop bool done = false; while (!done) //Will make an infinity loop unless we set done=true { //Clear screen with a light greymyengine.FillColour(200,200,200);//FIRST LOOP //x loop for for (x=1;x<50;x++){ //y loop for for (y=1;y<50;y++){ //Counter of the adjacent cells Counter=0; //Count the number of adjacent living cells if (CellMap[x-1][y-1]==1 or CellMap[x-1][y-1]==3)Counter++; if (CellMap[x-1][y]==1 or CellMap[x-1][y]==3)Counter++; if (CellMap[x-1][y+1]==1 or CellMap[x-1][y+1]==3)Counter++; if (CellMap[x][y-1]==1 or CellMap[x][y-1]==3)Counter++; if (CellMap[x][y+1]==1 or CellMap[x][y+1]==3)Counter++; if (CellMap[x+1][y-1]==1 or CellMap[x+1][y-1]==3)Counter++; if (CellMap[x+1][y]==1 or CellMap[x+1][y]==3)Counter++; if (CellMap[x+1][y+1]==1 or CellMap[x+1][y+1]==3)Counter++; //minimum adjacent cells = 0 //maximum adjacent cells = 8 //if a cell has is dead "0" and is surrounded by 3 cells will born if (CellMap[x][y]==0 and Counter==3)CellMap[x][y]=2; //Born //if a cell is living "1" and is surrounded by less than 2 cells, //or more than 3 cells, will die // the problem is that if we change the state from 0 to 1 or 1 to 0, //when we continue counting, the results will not be correct, so we //use a temporary state (2 for new born and 3 for dying cell), so //when we continue counting adjacent cells the result will be ok if (CellMap[x][y]==1){ if (Counter<2 or Counter >3)CellMap[x][y]=3; //Die } //draw the cell on the screen myengine.BlitTileset(x,y,CellMap[x][y]); }; //End for y }; //End for x //Update the screen with the back buffermyengine.Flip();} //SECOND LOOP //x loop for for (x=1;x<50;x++){ //y loop for for (y=1;y<50;y++){ //now we clean the map with the final cell state (1 or 0) if (CellMap[x][y]==2)CellMap[x][y]=1; //Born if (CellMap[x][y]==3)CellMap[x][y]=0; //Die //draw the cell on the screen myengine.BlitTileset(x,y,CellMap[x][y]); }; }; //update the screenmyengine.Flip();//wait 50 miliseconds to limit frame ratemyengine.Wait(50);} //End of main loop

Notice i have written a few lines of code with red color, I'm going to create a c++ class to encapsulate a simple engine so many SDL functions will be integrated in it, making easier the process to write programs; i have removed too code from the program to make it more readable, I will show the complete code later.

On the next post, our first Code::Blocks c++ project!

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