1 /* This file is part of Alienwave, a game by Alessandro Pira */
2
3 #include "shield.h"
4 #include "blit.h"
5 #include "aliens.h"
6 #include "xzarna.h"
7 #include "defs.h"
8
9 shield scudo;
10 // "scudo" is the italian word for shield
11
12 extern int x_ofs;
13 extern int y_ofs;
14 extern alien all_aliens[NUM_ALIENS];
15
init_shields()16 void init_shields()
17 {
18 scudo.x = -5;
19 scudo.state = SHIELD_MIN; // Down and recharging
20 scudo.blit = blit_shield;
21 scudo.clear = clear_shield;
22 }
23
open_shields(int x,int y)24 void open_shields(int x, int y)
25 {
26 if ( (scudo.state>0) && (scudo.x<-1) )
27 {
28 scudo.x = x;
29 scudo.y = y;
30 }
31 }
32
blit_shields()33 void blit_shields()
34 {
35 if (scudo.x >= -1)
36 {
37 scudo.blit(scudo.x+x_ofs,scudo.y+y_ofs,(scudo.state/SHIELD_STEP)+1);
38 }
39 else if (scudo.state>0) blit_shield_charge(x_ofs,y_ofs,scudo.state/(SHIELD_MAX/20));
40 }
41
clear_shields()42 void clear_shields()
43 {
44 if (scudo.x >= -1)
45 {
46 scudo.clear(scudo.x+x_ofs,scudo.y+y_ofs);
47 }
48 clear_shield_charge(x_ofs,y_ofs);
49 }
50
move_shields()51 void move_shields()
52 {
53 if (scudo.x<-1)
54 {
55 if (scudo.state<SHIELD_MAX)
56 scudo.state++;
57 }
58 else // The shield is on
59 {
60 scudo.state--;
61 if (scudo.state>0)
62 {
63 int i,rel_x,rel_y;
64 /* collision check */
65 for (i=0;i<NUM_ALIENS;i++)
66 {
67 rel_x=scudo.x-all_aliens[i].x;
68 rel_y=scudo.y-all_aliens[i].y;
69 if ( (rel_y>=0) && (rel_y<MAX_HEIGHT) &&
70 (rel_x > -9) && (rel_x < 8) )
71 {
72 int shift;
73 if (rel_x >= -1) shift=0x1FF>>(rel_x+1);
74 else shift=0x1FF<<(-(rel_x+1));
75 if ((all_aliens[i].collide[rel_y] & shift) != 0 )
76 {
77 blow_alien(i);
78 }
79 }
80 }
81 for (i=0;i<9;i++)
82 collide_queen(scudo.x+i,scudo.y,COL_SHIELD);
83 }
84 else
85 {
86 scudo.state = SHIELD_MIN;
87 scudo.x = -5;
88 }
89 }
90 }
91
92