A program in need of analysis

A program in need of analysis

Kikaru

Member #7,616

August 2006

OK, I wrote a program here:

#SelectExpand
   1#include "allegro.h"
   2#include "nl.h"
   3
   4//define some convenient constants
   5#define MODE GFX_AUTODETECT_WINDOWED
   6#define WIDTH 640
   7#define HEIGHT 480
   8#define S_VOLUME 25
   9#define BLACK makecol (0, 0, 0)
  10#define LIGHT_BLUE makecol (64, 128, 255)
  11#define WHITE makecol (255, 255, 255)
  12#define GRASS makecol (0, 255, 64)
  13#define R 0
  14#define L 1
  15#define SPD 2
  16#define BLOCKS 20
  17#define BLOCK_FALL 2
  18
  19//define class: Trace
  20class trace
  21{
  22public:
  23int x1, x2, y1, y2, active;
  24};
  25
  26//define class: Character
  27class character
  28{
  29public:
  30int x, y, dir, combo, score;
  31float x_spd, y_spd;
  32trace trail;
  33BITMAP *image;
  34void move();
  35};
  36
  37void character::move()
  38{
  39x += int(x_spd);
  40y += int(y_spd);
  41return;
  42}
  43
  44//define classes: part and thing
  45class part
  46{
  47public:
  48int x, y, active;
  49BITMAP *image;
  50};
  51
  52class thing
  53{
  54public:
  55int x, y, active, weight;
  56//BITMAP *image;
  57};
  58
  59//define class: game_timer
  60class game_timer
  61{
  62public:
  63int play_loop, play_sec, play_min;
  64};
  65
  66//variables
  67BITMAP *aimer, *buffer, *resources, *player_panel, *block_pic;
  68character player;
  69thing block[BLOCKS];
  70part piece[(BLOCKS+1)*2];
  71int mouseisdown, dash_delay, gravity, till_next, next_block = 50;
  72game_timer play_time, time_left;
  73
  74//it does what it says!
  75void set_direction(int goto_x, int goto_y)
  76{
  77//left
  78if (goto_x < player.x + 12)
  79{
  80player.x_spd = -SPD;
  81}
  82//right
  83if (goto_x > player.x - 12)
  84{
  85player.x_spd = SPD;
  86}
  87//up
  88if (goto_y < player.y + 12)
  89{
  90player.y_spd = -SPD;
  91}
  92//down
  93if (goto_y > player.y - 12)
  94{
  95player.y_spd = SPD;
  96}
  97//got diagonal?
  98if ((!(player.y_spd == 0))&&(!(player.x_spd == 0)))
  99{
 100player.y_spd = player.y_spd/2;
 101player.x_spd = player.x_spd/2;
 102}
 103return;
 104}
 105
 106//check for collisions
 107int is_cut(BITMAP *obj_layer ,int obj_x, int obj_y, int obj_size)
 108{
 109BITMAP *clip_board = create_bitmap(obj_size, obj_size);
 110int scan_x = 0, scan_y = 0;
 111blit(obj_layer, clip_board, obj_x - obj_size/2, obj_y - obj_size/2, 0, 0, obj_size, obj_size);
 112while (scan_y < obj_size-1)
 113{
 114    while (scan_x< obj_size-1)
 115    {
 116        if(getpixel(clip_board, scan_x, scan_y) == LIGHT_BLUE)
 117        {
 118                destroy_bitmap(clip_board);
 119                return 1;
 120        }
 121        scan_x += 1;
 122    }
 123    scan_y += 1;
 124    scan_x = 0;
 125}
 126destroy_bitmap(clip_board);
 127return 0;
 128}
 129
 130//main function
 131void main(void)
 132{
 133    //initialize allegro
 134    allegro_init();
 135    install_keyboard();
 136    install_mouse();
 137    install_timer();
 138    set_color_depth(24);
 139    if(set_gfx_mode(MODE, WIDTH, HEIGHT, 0, 0) != 0)
 140    {
 141        set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
 142        allegro_message(allegro_error);
 143        return;
 144    }
 145    text_mode(-1);
 146    install_sound(DIGI_AUTODETECT, MIDI_NONE, "");
 147    //initialize HawkNL
 148    nlInit();
 149    
 150    //load graphics
 151    resources = load_bitmap("ninja.bmp", NULL);
 152    
 153    //load sounds
 154
 155    //initalize settings
 156    player_panel = create_bitmap(192, 64);
 157    player.image = create_bitmap(64, 64);
 158    block_pic = create_bitmap(64, 64);
 159    stretch_blit(resources, block_pic, 0, 32, 32, 32, 0, 0, 64, 64);
 160    int i = 0;
 161    //while (i < 42)
 162    //{
 163    //piece<i>.image = create_bitmap(64, 64);
 164    //i += 1;
 165    //}
 166    buffer = create_bitmap(WIDTH, HEIGHT);
 167    aimer = create_bitmap(32, 32);
 168    blit(resources, aimer, 96, 0, 0, 0, 32, 32);
 169    stretch_blit(resources, player_panel, 0, 0, 96, 32, 0, 0, 192, 64);
 170    blit(player_panel, player.image, 64, 0, 0, 0, 64, 64);
 171    rectfill(buffer, 0, 0, WIDTH, HEIGHT, WHITE);
 172    destroy_bitmap(resources);
 173
 174
 175    //main loop
 176    while (!key[KEY_ESC])
 177    {
 178    
 179    //dashing
 180    if ((mouse_b & 1)&&(!mouseisdown)&&(dash_delay >= 12))
 181    {
 182    //new image
 183    blit(player_panel, player.image, 0, 0, 0, 0, 64, 64);
 184    //change direction
 185    if (mouse_x > player.x)
 186        player.dir = R;
 187    if (mouse_x < player.x)
 188        player.dir = L;
 189    //make the trail
 190    player.trail.x1 = player.x;
 191    player.trail.y1 = player.y;
 192    player.trail.x2 = mouse_x;
 193    player.trail.y2 = mouse_y;
 194    player.trail.active = 1;
 195    //move player
 196    set_direction(mouse_x, mouse_y);
 197    player.x = mouse_x;
 198    player.y = mouse_y;
 199    //reset
 200    dash_delay = 0;
 201    mouseisdown = TRUE;
 202    gravity = 0;
 203    }
 204    
 205    if (!mouse_b & 1)
 206        mouseisdown = FALSE;
 207    
 208    dash_delay += 1;
 209
 210    //trail vanishes... now!
 211    if (dash_delay >= 18)
 212        player.trail.active = 0;
 213    
 214    player.move();
 215    
 216    //fall
 217    if (dash_delay >= 15)
 218    {
 219        blit(player_panel, player.image, 128, 0, 0, 0, 64, 64);
 220        gravity += 1;
 221        player.y += gravity/3;
 222        player.x_spd = 0;
 223        player.y_spd = 0;
 224    }
 225    
 226    till_next += 1;
 227    //drop blocks
 228    i = 0;
 229    while (i < BLOCKS)
 230    {
 231    if ((!(block<i>.active))&&(till_next >= next_block - play_time.play_min*5))
 232    {
 233        block<i>.active = 1;
 234        block<i>.x = ((rand()%17)*32)+64;
 235        block<i>.y = -32;
 236        block<i>.weight = rand()%3 + BLOCK_FALL;
 237        till_next = 0;
 238        i = BLOCKS;
 239    }
 240    else
 241        i += 1;
 242    }
 243    //blocks fall
 244    i = 0;
 245    while (i < BLOCKS)
 246    {
 247    block<i>.y += block<i>.weight;
 248    if (block<i>.y >= 400)
 249    {
 250        block<i>.active = 0;
 251    }
 252    i += 1;
 253    }
 254
 255    //cut blocks
 256    i = 0;
 257    if (dash_delay < 3)
 258    {
 259    while (i < BLOCKS)
 260    {
 261    if (is_cut(screen, block<i>.x, block<i>.y, 64)&&(block<i>.active == 1)&&(block<i>.y > 16))
 262    {
 263        player.combo += 1;
 264        block<i>.active = 0;
 265    }
 266    i += 1;
 267    }
 268    }
 269    player.score += player.combo*player.combo;
 270    player.combo = 0;
 271    
 272    //bottom
 273    if (player.y >= 400)
 274    {
 275        player.y = 400;
 276        blit(player_panel, player.image, 64, 0, 0, 0, 64, 64);
 277    }
 278    
 279    //setup the buffer
 280    rectfill(buffer, 0, 0, WIDTH, HEIGHT, WHITE);
 281    //draw blocks
 282    i = 0;
 283    while (i < BLOCKS)
 284    {
 285    if (block<i>.active == 1)
 286        draw_sprite(buffer, block_pic, block<i>.x-32, block<i>.y-32);
 287    i += 1;
 288    }
 289    //draw player trail
 290    if (player.trail.active == 1)
 291        line(buffer, player.trail.x1, player.trail.y1, player.trail.x2, player.trail.y2, LIGHT_BLUE);
 292    //draw player
 293    if (player.dir == R)
 294        draw_sprite(buffer, player.image, player.x-32, player.y-32);
 295    else
 296        draw_sprite_h_flip(buffer, player.image, player.x-32, player.y-32);
 297
 298    //text
 299    textprintf(buffer, font, 100, 460, BLACK, "Score:%i", player.score);
 300    textprintf(buffer, font, 260, 460, BLACK, "%i' ", play_time.play_min);
 301    textprintf(buffer, font, 280, 460, BLACK, "%i'' ", play_time.play_sec);
 302    textprintf(buffer, font, 310, 460, BLACK, "%i", play_time.play_loop);
 303    
 304    //draw the mouse
 305    draw_sprite(buffer, aimer, mouse_x, mouse_y);
 306    
 307    //draw the screen
 308    blit(buffer, screen, 0, 0, 0, 0, WIDTH, HEIGHT);
 309    
 310    //timer
 311    play_time.play_loop += 1;
 312    if (play_time.play_loop >= 39)
 313    {
 314        play_time.play_sec += 1;
 315        play_time.play_loop -= 39;
 316    }
 317    if (play_time.play_sec >= 60)
 318    {
 319        play_time.play_min += 1;
 320        play_time.play_sec -= 60;
 321    }
 322    
 323    //delay
 324    rest(25);
 325    }
 326    
 327    //shut down HawkNL
 328    nlShutdown();
 329    //clean up
 330    destroy_bitmap(player_panel);
 331    destroy_bitmap(aimer);
 332    destroy_bitmap(buffer);
 333    return;
 334}
 335
 336END_OF_MAIN();

I have the linker set and everything works fine, only sometimes you kill an object when its up near the top. It ONLY happens when a block is near the top. anyone see what's causing it?

Richard Phipps

Member #1,632

November 2001

Quote:

only sometimes you kill an object when its up near the top

What do you mean? I don't understand the problem.

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Indeterminatus

Member #737

November 2000

I'm sorry, but I also don't know what the problem is. Could you elaborate on:

What's happening?
How is it reproducable?
What should happen if the code was well-formed?

Following are a few suggestions, which ~~as I always point out~~ are meant as suggestions, and are of course neither mandatory nor objective, so add a "imho" to everything I say

A construct like this:

int i = 0;
while ( i < SOMETHING ) {
  /* do something */
  i += 1;
}

Is better expressed with a for loop, like here:

for ( int i = 0; i < SOMETHING; ++i ) {
  /* do something */
}

It's not wrong, mind you, both work just fine.

On a similar note, assuming you won't need i to be a specific value later on, this could be rewritten:

int i = 0;
while ( i < SOMETHING ) {
  /* break out of loop */
  i = SOMETHING; // <-- this line I'm talking about
  ...

Breaking out of the loop can be achieved by making its condition false, but what I saw in your code, you don't need to execute the rest of the loop body, and you also don't access i in any way that it'd be important that it had the value SOMETHING.
There's a keyword for exactly that situation, namely break, which I find fits better here. There's another side of the coin, though, as break tends to make analysis of program flow somewhat more complex a task, which is why you'll find some programmers opposing its use. I don't want to get political about that, so I leave it up to you to decide - just pointing out another way (if you already knew that, you can ignore this comment ).

Some of the formatting might have been lost somewhere during the copy & paste, however I feel obliged to point out to follow at least basic indentation rules. I'm sure Google will know something about them.

In your class part, the member active is declared as int, however it is used like a boolean variable. I suggest using bool instead, because that's the data type you really want here.

edit: Fixed a typo.

_______________________________
Indeterminatus. [Atomic Butcher]
si tacuisses, philosophus mansisses

Kikaru

Member #7,616

August 2006

Sorry, I was rushed when I wrote that. During the game, blocks fall from the top of the screen. You need to draw lines through them using the mouse to cut them. For the blocks to be hit, the line needs to actually cross through the object's on-screen image. Right now, attacks will sometimes hit blocks near the top of the screen, even if the are on the opposite side of the screen form where you drew the line.

P.S. I might get a copy of the program up later.

Erkle

Member #3,493

May 2003

From what i can see, your is_cut function does the following:

Creates a bitmap of the same size as the object.
Blits a piece of the screen to the clipboard.

If obj_x > obj_size*3/2 or obj_y > obj_size*3/2 then this will be a white
square from outside the screen buffer.

Then check if any pixel in the buffer except those on the right or

bottom are light blue.

This doesn't seem to have anything to do with checking if a line cuts an object. My advice would be to start is_cut from scratch after asking how to do so in this thread. Try looking up do_line, it might be a good start.

If the writing above has offended you, you've read it wrong.....fool.
And if you read that wrong it means 'All of the above is opinion and is only to be treated as such.'

Kikaru

Member #7,616

August 2006

The is_cut function does the following: using its arguments, it grabs a portion of the bitmap (obj_layer), and scans it for LIGHT_BLUE pixels. LIGHT_BLUE is a color used ONLY in the slash lines. The -1 to obj_size are because position starts counting at zero. (If you have a bitmap 100 pixels wide, the far left will be 0, the far right will be 99)

However, thank you for pointing out about the size error.

EDIT: I changed the size, and it works now! thank you very much

EDIT2: How would do_line help at all?

Erkle

Member #3,493

May 2003

My bad, I got the source_x/y and dest_x/y back to front again:-[. Good thing 4.3 has a better format. I also assumed you wanted to check the line to see if an object was under it rather than check each object to see if the line is on it.

Quote:

The -1 to obj_size are because position starts counting at zero.

Then you want:
obj_y <= obj_size-1
but:
obj_y < obj_size
will be slightly more efficient.

On a side note: It would probably be more efficient to create clip_board in main() and pass it to is_cut so it doesn't have to be created and destroyed for every check.

If the writing above has offended you, you've read it wrong.....fool.
And if you read that wrong it means 'All of the above is opinion and is only to be treated as such.'

Kikaru

Member #7,616

August 2006

I worked out a way to use a do_line to eliminate the need for that. Suprise suprise?