no-reply@allegro.cc (David_at_wedu) — Sat, 01 Jul 2006 20:41:39 +0000

Chances are, this problem reeks of newbieness -- that maybe I'm just not initializing something right -- but it's a problem nonetheless. A program I copied from the book I'm reading, for the sake of messing around with mouse input, compiles just fine, but every time I execute it, the program immediately crashes and gives me one of those "Do you wish to report this error to MS?" dialogs.

If it helps to produce a solution, I'm working on a notebook computer with Windows XP Profesional. I'm kind of baffled here.

Here's the code:

1#include 
2 
3#define WHITE makecol(255,255,255)
4#define BLACK makecol(0,0,0)
5#define RED makecol(255,0,0)
6#define GREEN makecol(0,255,0)
7#define BLUE makecol(0,0,255)
8#define SMOKE makecol(140,130,120)
9 
10// point structure used to draw lines
11typedef struct POINT
12{
13    int x, y;
14}POINT;
15 
16// points array holds do_line points for drawing a line
17POINT points[2000];
18int curpoint, totalpoints;
19 
20// bitmap images
21BITMAP* buffer;
22BITMAP* crosshair;
23BITMAP* city;
24 
25// misc variables
26int st_x,st_y,en_x,en_y;
27int done = 0;
28int destroyed = 1;
29int n;
30int mx,my,mb;
31int score = -1;
32 
33void updatescore()
34{
35    // update and display the score
36    score = score+1;
37    textprintf_right_ex(buffer, font, SCREEN_W-5, 1, WHITE, -1, "SCORE: %d", score);
38}
39 
40void explosion(BITMAP* bmp, int x, int y, int finalcolor)
41{
42    int color, size;
43 
44    for (n=0;n<20;n++)
45    {
46        // generate a random color
47        color = makecol(rand()%255,rand()%255,rand()%255);
48        // random explosion side
49        size = 20+rand()%20;
50        // draw the filled circle
51        circlefill(bmp, x, y, size, color);
52        // short pause
53        rest(2);
54    }
55    // missile tracker looks for this explosion color
56    circlefill(bmp, x, y, 40, finalcolor);
57}
58 
59void doline(BITMAP* bmp, int x, int y, int d)
60{
61    // line callback function... fills the points array
62    points[totalpoints].x = x;
63    points[totalpoints].y = y;
64    totalpoints++;
65}
66 
67void firenewmissile()
68{
69    // activate the new missile
70    destroyed = 0;
71    totalpoints = 0;
72    curpoint = 0;
73 
74    // random starting location
75    st_x = rand() % (SCREEN_W-1);
76    st_y = 20;
77 
78    // random ending location
79    en_x = rand() % (SCREEN_W-1);
80    en_y = SCREEN_H-50;
81 
82    // construct the line point-by-point
83    do_line(buffer, st_x, st_y, en_x, en_y, 0, &doline);
84}
85 
86void movemissile()
87{
88    // grab a local copy of the current point
89    int x = points[curpoint].x;
90    int y = points[curpoint].y;
91 
92    // hide mouse pointer
93    scare_mouse();
94 
95    // erase missile
96    rectfill(buffer, x-6, y-3, x+6, y+1, BLACK);
97 
98    // see if missile was hit by defense weapon
99    if (getpixel(screen, x, y) == GREEN)
100    {
101        // missile destroyed! score a point
102        destroyed++;
103        updatescore();
104    } else {
105        // no hit, just draw the missile and smoke trail
106        //draw the smoke trail
107        putpixel(buffer, x, y-3, SMOKE);
108        // draw the missle
109        circlefill(buffer, x, y, 2, BLUE);
110    }
111    // show mouse pointer
112    unscare_mouse();
113 
114    // did the missle hit a city?
115    curpoint++;
116    if (curpoint >= totalpoints)
117    {
118        // destroy the missile
119        destroyed++;
120        // animate explosion directly on screen
121        explosion(screen, x, y, BLACK);
122        // show the damage on the backbuffer
123        circlefill(buffer, x, y, 40, BLACK);
124    }
125}
126 
127 
128int main()
129{
130    allegro_init();
131    set_color_depth(16);
132    set_gfx_mode(GFX_AUTODETECT_WINDOWED, 640, 480, 0, 0);
133    install_keyboard();
134    install_mouse();
135    install_timer();
136    srand(time(NULL));
137 
138    //create a secondary screen buffer
139    buffer = create_bitmap(640,480);
140 
141    // display title
142    textout_ex(buffer, font, "Strategic Defense (ESC to quit)", 0, 1, WHITE, -1);
143 
144    //display score
145    updatescore();
146 
147    //draw border around screen
148    rect(buffer, 0, 12, SCREEN_W-2, SCREEN_H-2, RED);
149 
150    // load and draw the city images
151    city = load_bitmap("city.bmp", NULL);
152 
153    for (n=0;n<5;n++)
154    {
155        masked_blit(city, buffer, 0, 0, 50+n*120, SCREEN_H-city->h-2, city->w, city->h);
156    }
157 
158    // load the mouse cursor
159    crosshair = load_bitmap("crosshair.bmp", NULL);
160    set_mouse_sprite(crosshair);
161    set_mouse_sprite_focus(15,15);
162    show_mouse(buffer);
163 
164    while (!key[KEY_ESC])
165    {
166        // grab the current mouse values
167        mx = mouse_x;
168        my = mouse_y;
169        mb = (mouse_b & 1);
170 
171        // fire another missile if needed
172        if (destroyed)
173        {
174            firenewmissile();
175        }
176 
177        // left mouse button, fire the defense weapon
178        if (mb)
179        {
180            explosion(screen, mx, my, GREEN);
181        }
182 
183        // update enemy missile position
184        movemissile();
185 
186        // update_screen
187        blit(buffer, screen, 0, 0, 0, 0, 640, 480);
188 
189        // pause
190        rest(10);
191    }
192 
193    set_mouse_sprite(NULL);
194    destroy_bitmap(city);
195    destroy_bitmap(crosshair);
196    allegro_exit();
197}
198END_OF_MAIN();

If anyone can help, it would be greatly appreciated!

no-reply@allegro.cc (miran) — Sat, 01 Jul 2006 20:43:37 +0000

Why do you not do any error checking?

EDIT: Oh yeah, I see now. You're reading that book...

Solution: check for errors and it will soon all be clear. Most probably one or more bitmaps that you try to load can't be loaded.

no-reply@allegro.cc (count) — Mon, 03 Jul 2006 05:38:52 +0000

What is this famous book, that people talk about here on the boards from time to time?

no-reply@allegro.cc (gnolam) — Mon, 03 Jul 2006 06:35:42 +0000

The Necronomicon All In One, by Jonathan Alhazred.

no-reply@allegro.cc (David_at_wedu) — Mon, 03 Jul 2006 21:24:26 +0000

Quote:

What is this famous book, that people talk about here on the boards from time to time?

It's called Game Programming All in One: second edition and the author is Jonathan Harbour. I really don't think the book is all that bad, but I have picked up on some of what people here have been saying in regards to bad coding practices, how he's basically anti-C++ (because he probably doesn't get it), and apparently the guy's a jerk if anyone dares to call him on any of his mistakes.

But, if the book gets me at least rolling on working with Allegro -- I'm about halfway through the book -- then I'll be happy.

no-reply@allegro.cc (BrknPhoenix) — Mon, 03 Jul 2006 21:27:10 +0000

I found the book pretty handy to get started, as well as for random things here and there, but now that I'm started I've pretty much already left that book behind As soon as the example programs in it started crashing I knew something was terribly wrong, hehe.

I don't know why he hates C++ though I went ahead and put all my allegro stuff in classes anyway, screw him >_>

no-reply@allegro.cc (David_at_wedu) — Mon, 03 Jul 2006 21:45:53 +0000

Quote:

As soon as the example programs in it started crashing I knew something was terribly wrong, hehe.

I haven't really had any of the examples crash, save for a few that used variable names that were defined elsewhere already (MAX comes to mind). Other than that, I've only encountered depreciated text handling functions, which I quickly looked up in the Allegro manual and updated.

Still, I do wish the book were C++-centric, if only because I learn better off seeing examples.

1	#include
2
3	#define WHITE makecol(255,255,255)
4	#define BLACK makecol(0,0,0)
5	#define RED makecol(255,0,0)
6	#define GREEN makecol(0,255,0)
7	#define BLUE makecol(0,0,255)
8	#define SMOKE makecol(140,130,120)
9
10	// point structure used to draw lines
11	typedef struct POINT
12	{
13	int x, y;
14	}POINT;
15
16	// points array holds do_line points for drawing a line
17	POINT points[2000];
18	int curpoint, totalpoints;
19
20	// bitmap images
21	BITMAP* buffer;
22	BITMAP* crosshair;
23	BITMAP* city;
24
25	// misc variables
26	int st_x,st_y,en_x,en_y;
27	int done = 0;
28	int destroyed = 1;
29	int n;
30	int mx,my,mb;
31	int score = -1;
32
33	void updatescore()
34	{
35	// update and display the score
36	score = score+1;
37	textprintf_right_ex(buffer, font, SCREEN_W-5, 1, WHITE, -1, "SCORE: %d", score);
38	}
39
40	void explosion(BITMAP* bmp, int x, int y, int finalcolor)
41	{
42	int color, size;
43
44	for (n=0;n<20;n++)
45	{
46	// generate a random color
47	color = makecol(rand()%255,rand()%255,rand()%255);
48	// random explosion side
49	size = 20+rand()%20;
50	// draw the filled circle
51	circlefill(bmp, x, y, size, color);
52	// short pause
53	rest(2);
54	}
55	// missile tracker looks for this explosion color
56	circlefill(bmp, x, y, 40, finalcolor);
57	}
58
59	void doline(BITMAP* bmp, int x, int y, int d)
60	{
61	// line callback function... fills the points array
62	points[totalpoints].x = x;
63	points[totalpoints].y = y;
64	totalpoints++;
65	}
66
67	void firenewmissile()
68	{
69	// activate the new missile
70	destroyed = 0;
71	totalpoints = 0;
72	curpoint = 0;
73
74	// random starting location
75	st_x = rand() % (SCREEN_W-1);
76	st_y = 20;
77
78	// random ending location
79	en_x = rand() % (SCREEN_W-1);
80	en_y = SCREEN_H-50;
81
82	// construct the line point-by-point
83	do_line(buffer, st_x, st_y, en_x, en_y, 0, &doline);
84	}
85
86	void movemissile()
87	{
88	// grab a local copy of the current point
89	int x = points[curpoint].x;
90	int y = points[curpoint].y;
91
92	// hide mouse pointer
93	scare_mouse();
94
95	// erase missile
96	rectfill(buffer, x-6, y-3, x+6, y+1, BLACK);
97
98	// see if missile was hit by defense weapon
99	if (getpixel(screen, x, y) == GREEN)
100	{
101	// missile destroyed! score a point
102	destroyed++;
103	updatescore();
104	} else {
105	// no hit, just draw the missile and smoke trail
106	//draw the smoke trail
107	putpixel(buffer, x, y-3, SMOKE);
108	// draw the missle
109	circlefill(buffer, x, y, 2, BLUE);
110	}
111	// show mouse pointer
112	unscare_mouse();
113
114	// did the missle hit a city?
115	curpoint++;
116	if (curpoint >= totalpoints)
117	{
118	// destroy the missile
119	destroyed++;
120	// animate explosion directly on screen
121	explosion(screen, x, y, BLACK);
122	// show the damage on the backbuffer
123	circlefill(buffer, x, y, 40, BLACK);
124	}
125	}
126
127
128	int main()
129	{
130	allegro_init();
131	set_color_depth(16);
132	set_gfx_mode(GFX_AUTODETECT_WINDOWED, 640, 480, 0, 0);
133	install_keyboard();
134	install_mouse();
135	install_timer();
136	srand(time(NULL));
137
138	//create a secondary screen buffer
139	buffer = create_bitmap(640,480);
140
141	// display title
142	textout_ex(buffer, font, "Strategic Defense (ESC to quit)", 0, 1, WHITE, -1);
143
144	//display score
145	updatescore();
146
147	//draw border around screen
148	rect(buffer, 0, 12, SCREEN_W-2, SCREEN_H-2, RED);
149
150	// load and draw the city images
151	city = load_bitmap("city.bmp", NULL);
152
153	for (n=0;n<5;n++)
154	{
155	masked_blit(city, buffer, 0, 0, 50+n*120, SCREEN_H-city->h-2, city->w, city->h);
156	}
157
158	// load the mouse cursor
159	crosshair = load_bitmap("crosshair.bmp", NULL);
160	set_mouse_sprite(crosshair);
161	set_mouse_sprite_focus(15,15);
162	show_mouse(buffer);
163
164	while (!key[KEY_ESC])
165	{
166	// grab the current mouse values
167	mx = mouse_x;
168	my = mouse_y;
169	mb = (mouse_b & 1);
170
171	// fire another missile if needed
172	if (destroyed)
173	{
174	firenewmissile();
175	}
176
177	// left mouse button, fire the defense weapon
178	if (mb)
179	{
180	explosion(screen, mx, my, GREEN);
181	}
182
183	// update enemy missile position
184	movemissile();
185
186	// update_screen
187	blit(buffer, screen, 0, 0, 0, 0, 640, 480);
188
189	// pause
190	rest(10);
191	}
192
193	set_mouse_sprite(NULL);
194	destroy_bitmap(city);
195	destroy_bitmap(crosshair);
196	allegro_exit();
197	}
198	END_OF_MAIN();

Mouse-enabled program immediately exits due to error