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| C++ is changing the value of ALLEGRO_COLOR when adding to a vector. |
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Darren Hoehna
Member #15,297
September 2013
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Hi all, I made a Ship class that stores the bitmap and the ALLEGRO_COLOR is stored inside the Ship object. I have a collection of Ships in a vector and the problem is that, once I push the newly created ship onto the vector, the ALLEGRO_COLOR changes to really low negative values. I bet this is a C++ thing, but I can't figure out why this is happening. Here is the lines of code where I am testing this out: 1Ship ship(SHIP_WIDTH, SHIP_HEIGTH, ship_X_Position, ship_Y_Position);
2ship.setColor(255, 0, 255);
3shipCollection.push_back(ship);
The color of the ship is correct. But when I access the color of this ship from shipCollection[0] the color value are messed up. What does that? Ship.h 1#pragma once
2#ifndef SHIP_H
3#define SHIP_H
4#include<iostream>
5#include<allegro5\allegro.h>
6#include<allegro5\allegro_native_dialog.h>
7#include <string>
8class Ship
9{
10public:
11 Ship(int width, int heigth, float upperLeft_X_Position, float upperLeft_Y_Position);
12 ~Ship(void);
13 Ship(const Ship &thisShip);
14 ALLEGRO_BITMAP* getImage();
15 void printShip();
16 void setColor(int red, int green, int blue);
17 ALLEGRO_COLOR getColor();
18 int width;
19 int heigth;
20 float upperLeft_X_Position;
21 float upperLeft_Y_Position;
22
23private:
24 ALLEGRO_BITMAP* bitmap;
25 ALLEGRO_COLOR shipColor;
26 void displayErorMessage(const char* message) const;
27};
28
29#endif
Ship.cpp 1#include "Ship.h"
2
3
4Ship::Ship(int width, int heigth, float upperLeft_X_Position, float upperLeft_Y_Position) : width(width), heigth(heigth),
5 upperLeft_X_Position(upperLeft_X_Position), upperLeft_Y_Position(upperLeft_Y_Position){
6 bitmap = al_create_bitmap(this->width, this->heigth);
7 if(bitmap == NULL)
8 displayErorMessage("Can't make bitmap.");
9 }
10
11 Ship::~Ship(void) {
12 al_destroy_bitmap(bitmap);
13 }
14
15 Ship::Ship(const Ship &thisShip) {
16 this->upperLeft_X_Position = thisShip.upperLeft_X_Position;
17 this->upperLeft_Y_Position = thisShip.upperLeft_Y_Position;
18 this->width = thisShip.width;
19 this->heigth = thisShip.heigth;
20 bitmap = al_create_bitmap(thisShip.width, thisShip.heigth);
21 if(bitmap == NULL)
22 displayErorMessage("Can't copy bitmap.");
23 }
24
25 void Ship::setColor(int red, int green, int blue) {
26 if(blue <= -1 || green <= -1 || red <= -1 || blue >= 256 || green >= 256 || red >= 256) { // invalid numbers
27 shipColor = al_map_rgb(0, 0, 0);
28 }
29 else {
30 shipColor = al_map_rgb(red, green, blue);
31 }
32 }
33
34 ALLEGRO_COLOR Ship::getColor() {
35 return shipColor;
36 }
37
38 ALLEGRO_BITMAP* Ship::getImage()
39 {
40 return bitmap;
41 }
42
43 void Ship::printShip() {
44 std::cout << "upperLeft_X_Position: " << upperLeft_X_Position << " ";
45 std::cout << "upperLeft_Y_Position: " << upperLeft_Y_Position << std::endl;
46 }
47
48 void Ship::displayErorMessage(const char* message) const {
49 ALLEGRO_DISPLAY* errorMessage = al_create_display(300, 300);
50 al_show_native_message_box(errorMessage, "Ship Error", "Ship Error", message, NULL, ALLEGRO_MESSAGEBOX_ERROR);
51 al_destroy_display(errorMessage);
52 }
Source.cpp 1#include<allegro5\allegro.h>
2#include<allegro5\allegro_native_dialog.h>
3#include <stdio.h>
4#include <vector>
5#include"Ship.h"
6
7
8
9enum KeyDirections { Up, Down, Left, Right };
10int SCREEN_WIDTH = 200;
11int SCREEN_HEGTH = 200;
12int SHIP_WIDTH = 10;
13int SHIP_HEIGTH = 10;
14double FPS = 1.0 / 60.0;
15float SHIPS_MOVEMENT = 4.0;
16int main(int argc, char **argv)
17{
18
19
20 std::vector<Ship> shipCollection;
21 float ship_X_Position = SCREEN_WIDTH / 2;
22 float ship_Y_Position = SCREEN_HEGTH / 2;
23 ALLEGRO_DISPLAY* mainDisplay = NULL;
24 ALLEGRO_TIMER* screenRefreshTimer = NULL;
25 ALLEGRO_EVENT_QUEUE* eventQueue = NULL;
26 bool KeysPressed[4] = { false, false, false, false };
27 bool redraw = true;
28 bool doExit = false;
29
30 if (!al_init()) {
31 al_show_native_message_box(mainDisplay, "Title", "Heading", "Text", NULL, ALLEGRO_MESSAGEBOX_ERROR);
32 return 0;
33 }
34
35 Ship ship(SHIP_WIDTH, SHIP_HEIGTH, ship_X_Position, ship_Y_Position);
36 ship.setColor(255, 0, 255);
37 shipCollection.push_back(ship);
38 std::cout << ship.getColor().r << std::endl;
39 std::cout << shipCollection[0].getColor().r << std::endl;
40 mainDisplay = al_create_display(SCREEN_WIDTH, SCREEN_HEGTH);
41
42 if (mainDisplay == NULL) {
43 al_show_native_message_box(mainDisplay, "Title", "Heading", "Text", NULL, ALLEGRO_MESSAGEBOX_ERROR);
44 return 0;
45 }
46
47 if (!al_install_keyboard()) {
48 al_show_native_message_box(mainDisplay, "Title", "Heading", "Text", NULL, ALLEGRO_MESSAGEBOX_ERROR);
49 al_destroy_display(mainDisplay);
50 }
51
52 screenRefreshTimer = al_create_timer(FPS);
53 if (screenRefreshTimer == NULL) {
54 al_show_native_message_box(mainDisplay, "Title", "Heading", "Text", NULL, ALLEGRO_MESSAGEBOX_ERROR);
55 al_destroy_display(mainDisplay);
56 return 0;
57 }
58
59
60 eventQueue = al_create_event_queue();
61 if (eventQueue == NULL) {
62 al_show_native_message_box(mainDisplay, "Title", "Heading", "Text", NULL, ALLEGRO_MESSAGEBOX_ERROR);
63 al_destroy_display(mainDisplay);
64 al_destroy_timer(screenRefreshTimer);
65 return 0;
66 }
67 al_set_target_bitmap(al_get_backbuffer(mainDisplay));
68
69 al_register_event_source(eventQueue, al_get_timer_event_source(screenRefreshTimer));
70 al_register_event_source(eventQueue, al_get_display_event_source(mainDisplay));
71 al_register_event_source(eventQueue, al_get_keyboard_event_source());
72 al_clear_to_color(al_map_rgb(0, 0, 0));
73 al_flip_display();
74 al_start_timer(screenRefreshTimer);
75
76 while (!doExit) {
77 ALLEGRO_EVENT thisEvent;
78 al_wait_for_event(eventQueue, &thisEvent);
79 if (thisEvent.type == ALLEGRO_EVENT_TIMER) {
80 for(int index = 0; index < shipCollection.size(); index++)
81 {
82 if (KeysPressed[Up] /*&& ship.upperLeft_Y_Position >= 4.0*/) {
83 shipCollection[index].upperLeft_Y_Position -= SHIPS_MOVEMENT;
84 }
85
86 if (KeysPressed[Down] /*&& ship.upperLeft_Y_Position <= 200 - 10 - 4.0*/) {
87 shipCollection[index].upperLeft_Y_Position += SHIPS_MOVEMENT;
88 }
89
90 if (KeysPressed[Left] /*&& ship.upperLeft_X_Position >= 4.0*/) {
91 shipCollection[index].upperLeft_X_Position -= SHIPS_MOVEMENT;
92 }
93
94 if (KeysPressed[Right] /*&& ship.upperLeft_X_Position <= 200 - 10 - 4.0*/) {
95 shipCollection[index].upperLeft_X_Position += SHIPS_MOVEMENT;
96 }
97 }
98
99 redraw = true;
100 }
101 else if (thisEvent.type == ALLEGRO_EVENT_DISPLAY_CLOSE) {
102 break;
103 }
104 else if (thisEvent.type == ALLEGRO_EVENT_KEY_DOWN) {
105 switch (thisEvent.keyboard.keycode) {
106 case ALLEGRO_KEY_UP:
107 KeysPressed[Up] = true;
108 break;
109 case ALLEGRO_KEY_DOWN:
110 KeysPressed[Down] = true;
111 break;
112 case ALLEGRO_KEY_LEFT:
113 KeysPressed[Left] = true;
114 break;
115 case ALLEGRO_KEY_RIGHT:
116 KeysPressed[Right] = true;
117 break;
118 }
119 }
120 else if (thisEvent.type == ALLEGRO_EVENT_KEY_UP) {
121 switch (thisEvent.keyboard.keycode) {
122 case ALLEGRO_KEY_UP:
123 KeysPressed[Up] = false;
124 break;
125 case ALLEGRO_KEY_DOWN:
126 KeysPressed[Down] = false;
127 break;
128 case ALLEGRO_KEY_LEFT:
129 KeysPressed[Left] = false;
130 break;
131 case ALLEGRO_KEY_RIGHT:
132 KeysPressed[Right] = false;
133 break;
134 }
135 }
136
137 if (redraw && al_is_event_queue_empty(eventQueue)) {
138 redraw = false;
139 al_clear_to_color(al_map_rgb(0, 0, 0));
140 //for(int shipIndex = 0; shipIndex < ShipCollection.size(); shipIndex++)
141 //{
142 // al_draw_bitmap(ShipCollection[shipIndex].getImage(), ShipCollection[shipIndex].upperLeft_X_Position,
143 // ShipCollection[shipIndex].upperLeft_Y_Position, 0);
144 //}
145
146 al_draw_bitmap(shipCollection[0].getImage(), shipCollection[0].upperLeft_X_Position,
147 shipCollection[0].upperLeft_Y_Position, 0);
148 /*
149 foreach Ship in the collections
150 draw it.
151 */
152 al_flip_display();
153 }
154 }
155
156 al_destroy_timer(screenRefreshTimer);
157 al_destroy_event_queue(eventQueue);
158 al_destroy_display(mainDisplay);
159}
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Edgar Reynaldo
Major Reynaldo
May 2007
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Darren Hoehna said:
Ship ship(SHIP_WIDTH, SHIP_HEIGTH, ship_X_Position, ship_Y_Position); ship.setColor(255, 0, 255); shipCollection.push_back(ship);
You're adding a copy of ship to your vector, not ship itself. To do that you need to make a vector of ship pointers so you don't get ships copying themselves. Your copy constructor for ship doesn't copy the color so it is still uninitialized since you haven't used a constructor initialization list : class Example { int i; float f; double d; public : Example() : i(0), f(0.0f) { // d is unitialized here printf("%lf\n" , d); } };
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Darren Hoehna
Member #15,297
September 2013
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Right, when I added the ALLEGRO_COLOR, I forgot to add that to my copy constructor. I understand. Thank you again. |
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