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Home » U++ Library support » U++ Widgets - General questions or Mixed problems » Help with a possible design problem?
| Help with a possible design problem? [message #7991] |
Fri, 02 February 2007 22:43  |
snap2000
Messages: 14
Registered: January 2007
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Promising Member |
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I'm trying to create a pong game that I will later add some power-ups to (affecting ball speed and paddle size). I've been making nice progress, however, I've hit a problem that I can't seem to get past. I've separated my game into the classes Ball, Player, and Pong (the main application). In my member function Ball::Update(), I'm trying to obtain the positions of my paddles (I planned on using player.GetRect()/computer.GetRect()), but the paddles are instanciated in my Pong class. I've tried making making them friend classes with public member variables and all types of crazy other things, but I can't seem to access player or computer from my Ball::Update function.
Is this simply a terrible design flaw (does anyone have a better idea), or is there some solution that I'm just missing? Thanks for your time if you decide to try and help. Here is my code so far (you may have to paste into editor to see it all, it's wide):
#include <CtrlLib/CtrlLib.h>
#define SCREENWIDTH 600
#define SCREENHEIGHT 480
#define PADDLEWIDTH 12
#define PADDLEHEIGHT 40
#define BALLSIZE 8
#define BALLSPEED 5
enum Which { PLAYER, COMPUTER };
class Ball {
private:
int bx;
float by; // Ball pos
int sx;
float sy; // Ball speed
int size; // Ball size
Point* samples; // Vector samples for collision detection
int numSamples; // Number of samples to be taken
int serve; // Who the ball is being served to
public:
Ball() { serve = -1; Reset(); }
Rect GetRect() { Rect r(int(bx), int(by), int(bx + size), int(by + size)); return r; }
void Update();
void GetVectorSamples();
void Reset();
};
void Ball::Reset() {
size = BALLSIZE; // Init ball size
bx = (SCREENWIDTH - size) / 2; // center ball horizontally
by = (SCREENHEIGHT - size) / 2; // center ball vertically
sx = BALLSPEED * serve; // Init ball x-speed
sy = 0; //TODO: Pick random angle // Init ball y-speed (angle)
}
void Ball::GetVectorSamples() {
numSamples = (sx > size) ? sx / size : 1; // Number of samples to take
float dy = sy / numSamples; // Slope of ball movement
samples = new Point[numSamples];
for(int s = 1; s <= numSamples; s++) {
samples[s - 1].x = bx + (s * size); // Calculate sample x-pos
samples[s - 1].y = int(by + (s * dy)); // Calculate sample y-pos
}
}
void Ball::Update() {
if(bx + sx > SCREENWIDTH) { // Ball exits to right of screen
// TODO: add score and re-serve ball
serve = -1;
Reset();
} else if(bx + size + sx < 0) { // Ball exits to left of screen
// TODO: add score and re-serve ball
serve = 1;
Reset();
} else { // Ball is still in play
GetVectorSamples();
// [[ HOW DO I GET ACCESS TO PADDLE? player/computer are in Pong class ]]
// TODO: Test each sample against nearest paddle for collision
// TODO: Correct angle and direction of ball if collided
// TODO: Else continue in direction:
bx += sx;
by += sy;
}
}
class Player {
private:
int score, px, py, height;
Which who;
public:
Player() { }
Player(Which w);
int GetScore() { return score; }
Rect GetRect() { Rect r(px, py, px + PADDLEWIDTH, py + height); return r; }
void Update();
};
Player::Player(Which w) {
score = 0; // Init score
py = (SCREENHEIGHT - PADDLEHEIGHT) / 2; // Init paddle y-pos
height = PADDLEHEIGHT; // Init paddle height
px = (w == PLAYER)
? 10 // Set player paddle x-pos
: SCREENWIDTH - PADDLEWIDTH - 10; // Set computer paddle x-pos
}
void Player::Update() {
switch(who) {
case PLAYER:
// TODO: Get mouse y pos
break;
case COMPUTER:
// TODO: Move computer paddle toward ball
break;
}
}
class Pong : public TopWindow {
public:
void Paint(Draw& w);
private:
Player player, computer;
Ball ball;
public:
typedef Pong CLASSNAME;
Pong();
void Update();
};
void Pong::Update() {
// player.Update(); // Update player paddle position
// computer.Update(); // Update computer paddle position
ball.Update(); // Update ball position
Refresh();
}
void Pong::Paint(Draw& w) {
w.DrawRect(GetSize(), SBlack);
w.DrawRect(player.GetRect(), SWhite);
w.DrawRect(computer.GetRect(), SWhite);
w.DrawRect(ball.GetRect(), SWhite);
/* For showing projected samples ( samples and numSamples need to be made public to work )
for(int i = 0; i < ball.numSamples; i++) {
//w.DrawText(SCREENWIDTH / 2, 10 + 10 * i, ball.samples[i].ToString(), StdFont(), SWhite);
w.DrawRect(ball.samples[i].x, ball.samples[i].y, BALLSIZE, BALLSIZE, SWhite);
}
*/
}
Pong::Pong() {
Title("Snap.Pong");
SetRect(0, 0, SCREENWIDTH, SCREENHEIGHT);
MinimizeBox();
player = Player(PLAYER); // Init player
computer = Player(COMPUTER); // Init computer
BackPaint();
Update();
SetTimeCallback(-25, THISBACK(Update));
}
GUI_APP_MAIN
{
Pong().Run();
}
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| Re: Help with a possible design problem? [message #7996 is a reply to message #7991] |
Sat, 03 February 2007 01:04  |
snap2000
Messages: 14
Registered: January 2007
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Promising Member |
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I tried implementing the changes, but I'm getting a few compiler errors with this particular code:
#include <CtrlLib/CtrlLib.h>
#define SCREENWIDTH 600
#define SCREENHEIGHT 480
#define PADDLEWIDTH 12
#define PADDLEHEIGHT 40
#define BALLSIZE 8
#define BALLSPEED 5
enum Which { PLAYER, COMPUTER };
class Ball;
class Player;
class Pong;
class Ball {
private:
int bx;
float by; // Ball pos
int sx;
float sy; // Ball speed
int size; // Ball size
Point *samples; // Vector samples for collision detection
int numSamples; // Number of samples to be taken
int serve; // Who the ball is being served to
bool paused; // If game is paused
Player *player, *computer; // Paddles
public:
Ball() { serve = -1; Reset(); }
Rect GetRect() { Rect r(int(bx), int(by), int(bx + size), int(by + size)); return r; }
void Update(); // Update ball position
void CalculateVectorSamples(); // Calculate collision sample points
void Reset(); // Reset ball pos/attrs
void SetPaddles(Player *p, Player *c); // Set pointers to paddles
void Pause(bool p = true) { paused = p; } // Pause/unpause the game
bool IsPaused() { return paused; } // Return if paused or not;
};
void Ball::SetPaddles(Player *p, Player *c) {
player = p;
computer = c;
}
void Ball::Reset() {
size = BALLSIZE; // Init ball size
bx = (SCREENWIDTH - size) / 2; // center ball horizontally
by = (SCREENHEIGHT - size) / 2; // center ball vertically
sx = BALLSPEED * serve; // Init ball x-speed
sy = 0; //TODO: Pick random angle // Init ball y-speed (angle)
}
void Ball::CalculateVectorSamples() {
numSamples = (sx > size) ? sx / size : 1; // Number of samples to take
float dy = sy / numSamples; // Slope of ball movement
samples = new Point[numSamples];
for(int s = 1; s <= numSamples; s++) {
samples[s - 1].x = bx + (s * size); // Calculate sample x-pos
samples[s - 1].y = int(by + (s * dy)); // Calculate sample y-pos
}
}
void Ball::Update() {
if(IsPaused()) {
return;
} else if(bx + sx > SCREENWIDTH) { // Ball exits to right of screen
// TODO: add score and re-serve ball
serve = -1;
Reset();
} else if(bx + size + sx < 0) { // Ball exits to left of screen
// TODO: add score and re-serve ball
serve = 1;
Reset();
} else { // Ball is still in play
CalculateVectorSamples();
PromptOK(AsString(player->GetScore()));
Pause();
// [[ HOW DO I GET ACCESS TO PADDLE? player/computer are in Pong class ]]
// TODO: Test each sample against nearest paddle for collision
// TODO: Correct angle and direction of ball if collided
// TODO: Else continue in direction:
bx += sx;
by += sy;
}
}
class Player {
private:
int score, px, py, height;
Which who;
Ball *ball;
public:
Player() { }
Player(Which w, Ball *b);
int GetScore() { return score; }
Rect GetRect() { Rect r(px, py, px + PADDLEWIDTH, py + height); return r; }
void Update();
};
Player::Player(Which w, Ball *b) {
ball = b;
score = 0; // Init score
py = (SCREENHEIGHT - PADDLEHEIGHT) / 2; // Init paddle y-pos
height = PADDLEHEIGHT; // Init paddle height
px = (w == PLAYER)
? 10 // Set player paddle x-pos
: SCREENWIDTH - PADDLEWIDTH - 10; // Set computer paddle x-pos
}
void Player::Update() {
if(ball->IsPaused())
return;
switch(who) {
case PLAYER:
// TODO: Get mouse y pos
break;
case COMPUTER:
// TODO: Move computer paddle toward ball
break;
}
}
class Pong : public TopWindow {
public:
void Paint(Draw& w);
private:
Player player, computer;
Ball ball;
public:
typedef Pong CLASSNAME;
Pong();
void Update();
};
void Pong::Update() {
// player.Update(); // Update player paddle position
// computer.Update(); // Update computer paddle position
ball.Update(); // Update ball position
Refresh();
}
void Pong::Paint(Draw& w) {
w.DrawRect(GetSize(), SBlack);
w.DrawRect(player.GetRect(), SWhite);
w.DrawRect(computer.GetRect(), SWhite);
w.DrawRect(ball.GetRect(), SWhite);
/* For showing projected samples ( samples and numSamples need to be made public to work )
for(int i = 0; i < ball.numSamples; i++) {
//w.DrawText(SCREENWIDTH / 2, 10 + 10 * i, ball.samples[i].ToString(), StdFont(), SWhite);
w.DrawRect(ball.samples[i].x, ball.samples[i].y, BALLSIZE, BALLSIZE, SWhite);
}
*/
}
Pong::Pong() {
Title("Snap.Pong");
SetRect(0, 0, SCREENWIDTH, SCREENHEIGHT);
MinimizeBox();
player = Player(PLAYER, &ball); // Init player
computer = Player(COMPUTER, &ball); // Init computer
ball.SetPaddles(&player, &computer); // Pass paddles to Ball class
BackPaint();
Update();
SetTimeCallback(-25, THISBACK(Update));
}
GUI_APP_MAIN
{
Pong().Run();
}
The errors say:
| Quote: |
C:\Apps\Pong\main.cpp: In member function `void Ball::Update()':
C:\Apps\Pong\main.cpp:77: error: invalid use of undefined type `struct Player'
C:\Apps\Pong\main.cpp:14: error: forward declaration of `struct Player'
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Apparently it doesn't like me referring to player, and if I reverse the ball and player classes, me referring to the ball class. So, I'm stuck again.  
For some reason it doesn't like me
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