Inconsistent Behaviour Between 2 Players of Game - c++

Question

I've been making a game for an English presentation (I know right?) and I've been having a few weird problems recently.
At this stage, there are two squares for the players that can fire bullets. When the bullets hit the side of the screen or the middle border, they should disappear and possibly be reused later.
The problem is, first of all, when either player shoots up or down, the bullets disappear into the top/bottom/middle of the screen like they're supposed to. If player 2 shoots a few to the side, as soon as one hits, they seem to all disappear (only player 2's bullets) and I have to wait a few seconds before it starts shooting again.
The main problem though, is that even when I use the exact same code modified for player 1 instead of player 2, when player 1's first shot to hit the side of the screen gets there, it segfaults the program.
The REALLY odd thing is that at one point, this happened, and without changing anything, I ran it again and it all worked perfectly fine. It might have to do with the order of bullets between player 1 and 2, or even where I shoot first. I've tried recreating it, but no results yet.
Just a note before you try to compile the code, I used a wrapper I made to make the window with ease. I noted down what goes on behind the scenes with /// comments though, so adding that info into whatever method you use to make your windows will work just as well.
Problem areas are listed near the bottom:
///Works best on 1280x1024 resolution
///1 vs 1 splitscreen game that involves flying around and shooting things
///angles start at 0 facing upwards and increase clockwise
#include <window.h> //incomplete wrapper, but works perfectly for quick, easy window creation
#define _USE_MATH_DEFINES //for M_PI
#include <cmath> //for M_PI
#include <iostream> //used for debugging
using std::cout; //output
struct Actions //actions a player can take
{
bool up; //if player is moving in these 4 directions, they will be true
bool left;
bool down;
bool right;
bool shoot; //if player is shooting, this will be true
};
struct Player //a player
{
Player() {};
void fire(); //fire a bullet
void checkActions (HWND); //check what actions player is taking
double x; //position (centre of square)
double y;
double angle; //angle (might add diagonals so...)
int pnum; //player number (0 or 1)
COLORREF colour; //player's colour
Actions action; //player's actions
};
struct Bullet //a bullet
{
double x; //position (centre of square)
double y;
Player owner; //owner of bullet
int index; //bullet's index in array
double angle; //bullet's angle
};
Player *p = new Player[2]; //2 players
Bullet **bullet; //2d array of bullets
int bcount[2] = {0}; //number of bullets for each player
int btime [2] = {0}; //timer for bullets
const double PLSIZE = 10; //player size = 20x20 square (10 from centre outwards)
const double BSIZE = 2; //bullet size = 4x4 square
const double SPEED = 1; //player's moving speed is 1
const int BDELAY = 100; //delay between bullets is 100ms
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM); //window procedure
void OnPaint (HDC, HWND); //painting function
void moveBullets (HWND); //calculates bullet positions
void deleteBullet (int, int); //"deletes" a bullet
int main() //main function
{
//hide(console()); //hides console window (currently showing for debugging)
bullet = new Bullet*[2]; //create bullet array of 1000/player (I'll size down the 1000 later)
bullet[0] = new Bullet[1000];
bullet[1] = new Bullet[1000];
p[0].x = 630; //player 1's position
p[0].y = 250;
p[0].colour = RGB(255,0,0); //player 1 is red
p[0].pnum = 0; //player 1's number is 0
p[0].angle = 0; //face upwards
p[0].action = {0}; //player 1 is doing nothing
p[1].x = 630; //player 2's position
p[1].y = 750;
p[1].colour = RGB(0,0,255); //player 2 is blue
p[1].pnum = 1; //player 2's number is 1
p[1].angle = 0; //face upwards
p[1].action = {0}; //player 2 is doing nothing
Window window; //create window object (part of wrapper, sets default values for class and window)
///background = (HBRUSH)COLOR_WINDOW
///class name = "Default Wrapper Class"
///hInstance = GetModuleHandle (NULL)
///all others are standard default or 0
window.createClass(WndProc); //create class using earlier-mentioned window procedure
window.setStyle(WS_OVERLAPPEDWINDOW | WS_MAXIMIZE); //set window style to overlapped and maximized
window.setTitle (L"Word Blaster"); //set window title to "Word Blaster" (it's an English project, shush)
///x/y/width/height = CW_USEDEFAULT
///class name = other class name
///hInstance = GetModuleHandle (NULL)
///all others are standard default or 0
HWND hwnd = window.createWindow(); //create window
MSG msg; //message loop
while(GetMessage(&msg,0,0,0) > 0)
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) //window proc
{
HDC hdc; //hdc for painting
PAINTSTRUCT ps; //paintstruct for painting
bool ret = false; //return value (you'll see later)
switch(msg)
{
case WM_CREATE: //currently not in use
break;
case WM_KEYDOWN: //check for pressed keys
switch (wParam) //keycode
{
case 0x57: //'w'
p[0].action.up = true; //player 1 wants to move up (couldn't just change position here or no diagonal movement)
break;
case 0x41: //'a', left
p[0].action.left = true;
break;
case 0x53: //'s', down
p[0].action.down = true;
break;
case 0x44: //'d', right
p[0].action.right = true;
break;
case 0x20: // space, shoot
p[0].action.shoot = true;
break;
case VK_UP: //up arrow, player 2 up
p[1].action.up = true;
break;
case VK_LEFT: //left arrow
p[1].action.left = true;
break;
case VK_DOWN: //down arrow
p[1].action.down = true;
break;
case VK_RIGHT: //right arrow
p[1].action.right = true;
break;
case VK_RETURN: //either enter key, p2 shoot
p[1].action.shoot = true;
break;
}
break;
case WM_KEYUP: //check for unpressed keys
switch (wParam)
{
case 0x57: //'w', player 1 should stop moving up
p[0].action.up = false;
break;
case 0x41: //all same order as above
p[0].action.left = false;
break;
case 0x53:
p[0].action.down = false;
break;
case 0x44:
p[0].action.right = false;
break;
case 0x20: // space
p[0].action.shoot = false;
break;
case VK_UP:
p[1].action.up = false;
break;
case VK_LEFT:
p[1].action.left = false;
break;
case VK_DOWN:
p[1].action.down = false;
break;
case VK_RIGHT:
p[1].action.right = false;
break;
case VK_RETURN:
p[1].action.shoot = false;
break;
}
break;
case WM_PAINT: //draw on screen
hdc = BeginPaint (hwnd, &ps); //prepare window for drawing
OnPaint (hdc,hwnd); //draw
EndPaint (hwnd, &ps); //finish drawing
break;
case WM_CLOSE: //if ready to close
show(console()); //show console window in case it doesn't close
end(); //close console window (PostMessage (GetConsoleWindow(),WM_CLOSE,0,0))
DestroyWindow(hwnd); //close main window
break;
case WM_DESTROY: //window is closing
PostQuitMessage(0); //post WM_QUIT to end (probably won't get here since console closes earlier)
break;
case WM_ERASEBKGND: //if background is going to be erased, don't let it (causes flicker)
ret = true; //hold that thought for a bit
break;
}
p[0].checkActions(hwnd); //check player 1's actions
p[1].checkActions(hwnd); //check player 2's actions
moveBullets (hwnd); //move any bullets
InvalidateRect (hwnd,NULL,true); //update window
Sleep (1); //delay a bit
if (!ret) return DefWindowProc(hwnd, msg, wParam, lParam); //if WM_ERASEBKGND wasn't called, take default action
}
void Player::fire() //fire a bullet
{
bullet [pnum][bcount[pnum]].x = x; //bullet starts in player's centre
bullet [pnum][bcount[pnum]].y = y;
bullet [pnum][bcount[pnum]].owner = *this; //owner of bullet is the object calling this function
bullet [pnum][bcount[pnum]].index = bcount[pnum]; //index of bullet is the number of bullets for player
bullet [pnum][bcount[pnum]].angle = angle; //angle of bullet is player's angle
while (
(bullet[pnum][bcount[pnum]].x - BSIZE < x + PLSIZE && bullet[pnum][bcount[pnum]].x - BSIZE > x - PLSIZE //left side of bullet inside player OR
|| bullet[pnum][bcount[pnum]].x + BSIZE < x + PLSIZE && bullet[pnum][bcount[pnum]].x + BSIZE > x - PLSIZE) //right side in player --- AND ---
&& (bullet[pnum][bcount[pnum]].y - BSIZE < y + PLSIZE && bullet[pnum][bcount[pnum]].y - BSIZE > y - PLSIZE //top in player OR
|| bullet[pnum][bcount[pnum]].y + BSIZE < y + PLSIZE && bullet[pnum][bcount[pnum]].y + BSIZE > y - PLSIZE) //bottom in player
)
{
bullet[pnum][bcount[pnum]].x += sin (bullet[pnum][bcount[pnum]].angle * M_PI / 180); //start moving bullet until it's out
bullet[pnum][bcount[pnum]].y -= cos (bullet[pnum][bcount[pnum]].angle * M_PI / 180);
}
btime [pnum] = GetTickCount(); //set up bullet delay for that player
++bcount[pnum]; //increase number of bullets for that player
}
void Player::checkActions (HWND hwnd) //check player's actions
{
RECT r;
GetClientRect (hwnd, &r); //get canvas space
if (action.up) //if moving up
{
y -= SPEED; //change y position
angle = 0; //change angle
if (pnum == 0) //if player 1
{
if (y - PLSIZE < 1) y = PLSIZE + 1; //check top of screen boundary
}
else //if player 2
{
if (y - PLSIZE < r.bottom / 2 + 5) y = r.bottom / 2 + 5 + PLSIZE; //check middle boundary
}
}
if (action.left) //if moving left
{
x -= SPEED; //change x position
angle = 270; //change angle
if (x - PLSIZE < 1) x = PLSIZE + 1; //check left of screen boundary
}
if (action.down) //down is opposite of up
{
y += SPEED;
angle = 180;
if (pnum == 0)
{
if (y + PLSIZE > r.bottom / 2 - 5) y = r.bottom / 2 - 5 - PLSIZE;
}
else
{
if (y + PLSIZE > r.bottom) y = r.bottom - PLSIZE;
}
}
if (action.right) //right is opposite of left
{
x += SPEED;
angle = 90;
if (x + PLSIZE > r.right) x = r.right - PLSIZE;
}
if (action.shoot && GetTickCount() - btime [pnum] > BDELAY) fire(); //if player wants to shoot and enough time has passed, fire bullet
}
void OnPaint (HDC hdc, HWND hwnd) //draw stuff
{
RECT r;
GetClientRect (hwnd, &r); //get canvas area
HDC buffer = CreateCompatibleDC (hdc); //create buffer DC
HBITMAP bitmap = CreateCompatibleBitmap (hdc,r.right,r.bottom); //create buffer bitmap
HBITMAP oldBM = (HBITMAP)SelectObject (buffer, bitmap); //create another bitmap
HBRUSH player1brush = CreateSolidBrush(p[0].colour); //player 1's brush
HBRUSH player2brush = CreateSolidBrush(p[1].colour); //player 2's brush
HBRUSH blackBrush = CreateSolidBrush (RGB(0,0,0)); //black brush
HPEN /*player1*/pen = CreatePen (PS_NULL,1,RGB(255,0,0)); //don't need pen
BitBlt(buffer,0,0,r.right,r.bottom,NULL,0,0,WHITENESS); //erase bitmap background
SelectObject(buffer,pen); //select pen (since I need one to do anything)
SelectObject (buffer, blackBrush); //select black brush
Rectangle (buffer, 0, r.bottom / 2 - 5, r.right, r.bottom / 2 + 5); //draw middle line
// MoveTo () //these comments are because I was about to change the graphics to ships
SelectObject (buffer,player1brush); //select player 1's brush
Rectangle (buffer,p[0].x-PLSIZE,p[0].y-PLSIZE,p[0].x+PLSIZE,p[0].y+PLSIZE); //draw player 1
SelectObject (buffer,player2brush); //do the same for p2
Rectangle (buffer,p[1].x-PLSIZE,p[1].y-PLSIZE,p[1].x+PLSIZE,p[1].y+PLSIZE);
if (bcount[0] > 0) //if p1 has a bullet
{
SelectObject (buffer, blackBrush); //select black brush
for (int i = 0; i < bcount[0]; ++i) //draw bullet(s)
{
Ellipse (buffer, bullet [0][i].x - BSIZE, bullet [0][i].y - BSIZE, bullet [0][i].x + BSIZE, bullet [0][i].y + BSIZE);
}
}
if (bcount[1] > 0) //same goes for p2
{
SelectObject (buffer, blackBrush);
for (int i = 0; i < bcount[1]; ++i)
{
Ellipse (buffer, bullet [1][i].x - BSIZE, bullet [1][i].y - BSIZE, bullet [1][i].x + BSIZE, bullet [1][i].y + BSIZE);
}
}
BitBlt(hdc, 0,0, r.right , r.bottom, buffer, 0,0, SRCCOPY); //copy buffer bitmap to window
DeleteObject (player1brush); //delete stuff
DeleteObject (player2brush);
DeleteObject (pen);
SelectObject (buffer, oldBM);
DeleteObject (bitmap);
DeleteDC(buffer);
}
void moveBullets (HWND hwnd) //move the bullets ***PROBLEM AREA***
{
RECT r;
GetClientRect (hwnd, &r); //get canvas area
if (bcount[0] > 0) //if p1 has bullet(s)
{
for (int i = 0; i < bcount[0]; ++i) //go through p1's bullets
{
///DOESN'T WORK
bullet [0][i].x += sin (bullet [0][i].angle * M_PI / 180); //move the bullet horizontally
if (bullet [0][i].x - BSIZE < 1 || bullet [0][i].x + BSIZE > r.right) //if out of bounds
{
deleteBullet (0, bullet [0][i].index); //delete the bullet
--i; //if bullet [2] was deleted, bullet [2] will now be the old bullet [3] so recheck this one next time
}
///WORKS PERFECTLY
bullet [0][i].y -= cos (bullet [0][i].angle * M_PI / 180); //do same for y, including middle border
if (bullet [0][i].y - BSIZE < 1 || bullet [0][i].y + BSIZE > r.bottom / 2 - 5)
{
deleteBullet (0, bullet [0][i].index);
--i;
}
}
}
if (bcount[1] > 0) //exact same thing (I checked a LOT) for p2
{
for (int i = 0; i < bcount[1]; ++i)
{
///WORKS PERFECTLY (at least in the p1 sense, there is a slight problem)
bullet [1][i].x += sin (bullet [1][i].angle * M_PI / 180);
if (bullet [1][i].x - BSIZE < 1 || bullet [1][i].x + BSIZE > r.right)
{
deleteBullet (1, bullet [1][i].index);
--i;
}
///WORKS PERFECTLY
bullet [1][i].y -= cos (bullet [1][i].angle * M_PI / 180);
if (bullet [1][i].y - BSIZE < r.bottom / 2 + 5 || bullet [1][i].y + BSIZE > r.bottom)
{
deleteBullet (1, bullet [1][i].index);
--i;
}
}
}
}
void deleteBullet (int player, int index) //delete bullet ***PROBLEM AREA***
{
if (index != bcount [player] - 1) //if it isn't the last bullet
{
for (int j = index; j < bcount[player] - 1; ++j) //go from here to the end of the current bullets - 1
{
bullet [player][j] = bullet [player][j+1]; //copy the next bullet into this spot
--bullet [player][j].index; //change the index of the bullet since it was moved back one
}
}
--bcount [player]; //lessen the bullet count, this is all that's needed if it's the last bullet
}
Any help with said problems or with something else you notice would be greatly appreciated.
EDIT: one side thing I forgot to ask was if there was a better way to continuously do things like move bullets for example than to put all that outside of the switch in the window procedure and the DefWindowProc after it.

Answer 1

It looks like deleteBullet may get called twice on the same i inside the loop for (i=0...) in moveBullets. I think this could happen if the bullet is moving diagonally. I'm not sure it's the cause of the trouble, though.
First English question I've seen on stackoverflow!