game.c

   1 #include <SDL2/SDL.h>
   2
   3 #include <assert.h>
   4 #include <stdbool.h>
   5 #include <math.h>
   6
   7 #include "game.h"
   8
   9 #define SPEED  0.00006
  10 #define ROTATE 0.00004
  11 #define BULL_SPEED 0.008
  12
  13 Player g_player[MAX_PLAYERS];
  14 Bullet g_bullet[MAX_BULLETS];
  15
  16 void g_player_set(unsigned int id, bool live, float x, float y, float r, float vx, float vy, float vr) {
  17         assert(id < MAX_PLAYERS);
  18         g_player[id] = (Player) {
  19                 .updated = true,
  20                 .live    = live,
  21                 .x       = x,
  22                 .y       = y,
  23                 .r       = r,
  24                 .vx      = vx,
  25                 .vy      = vy,
  26                 .vr      = vr,
  27         };
  28 }
  29
  30 void g_bullet_set(unsigned int id, unsigned int owner, bool live, float x, float y, float vx, float vy, int tick) {
  31         assert(id < MAX_BULLETS);
  32         assert(owner < MAX_PLAYERS);
  33         g_bullet[id] = (Bullet) {
  34                 .live  = live,
  35                 .owner = owner,
  36                 .x     = x,
  37                 .y     = y,
  38                 .vx    = vx,
  39                 .vy    = vy,
  40                 .tick  = tick,
  41         };
  42 }
  43
  44 static int freebullet() {
  45         for(int i = 0; i < MAX_BULLETS; i++)
  46                 if(!g_bullet[i].live)
  47                         return i;
  48         return -1;
  49 }
  50
  51 static void moveplayer(int id, float speed) {
  52         g_player[id].vx += speed * cos(g_player[id].r * 2 * M_PI);
  53         g_player[id].vy += speed * sin(g_player[id].r * 2 * M_PI);
  54 }
  55
  56 static void roteplayer(int id, float speed) {
  57         g_player[id].vr += speed;
  58 }
  59
  60 static void fireplayer(int id) {
  61         int j = freebullet();
  62         if(j < 0)
  63                 return;
  64
  65         float vx = BULL_SPEED * cos(g_player[id].r * 2 * M_PI);
  66         float vy = BULL_SPEED * sin(g_player[id].r * 2 * M_PI);
  67         g_bullet_set(j, id, true, g_player[id].x, g_player[id].y, vx, vy, 0);
  68 }
  69
  70 static void checkspacebound(float * a) {
  71         float x = *a;
  72         if(x < -1)
  73                 x = fabs(x);
  74         else if(x > 1)
  75                 x = -x;
  76         *a = x;
  77 }
  78
  79 static bool collide(float x1, float y1, float r1, float x2, float y2, float r2) {
  80         float l = sqrtf(powf(x1 - x2, 2) + powf(y1 - y2, 2));
  81         return ((l - r1 - r2) <= 0);
  82 }
  83
  84 void g_player_does(unsigned int id, DoesCode code) {
  85         assert(id < MAX_PLAYERS);
  86         g_player[id].updated = true;
  87         switch(code) {
  88         case DOES_UP:    moveplayer(id, SPEED); break;
  89         case DOES_DOWN:  moveplayer(id, -SPEED); break;
  90         case DOES_LEFT:  roteplayer(id, -ROTATE); break;
  91         case DOES_RIGHT: roteplayer(id, ROTATE); break;
  92         case DOES_FIRE:  fireplayer(id); break;
  93         }
  94 }
  95
  96 void g_update() {
  97         for(int i = 0; i < MAX_PLAYERS; i++) {
  98                 if(g_player[i].live) {
  99                         g_player[i].updated = true;
 100                         g_player[i].x += g_player[i].vx;
 101                         g_player[i].y += g_player[i].vy;
 102                         g_player[i].r += g_player[i].vr;
 103                         checkspacebound(&g_player[i].x);
 104                         checkspacebound(&g_player[i].y);
 105                 }
 106         }
 107
 108         for(int i = 0; i < MAX_BULLETS; i++) {
 109                 if(g_bullet[i].live) {
 110                         g_bullet[i].updated = true;
 111                         g_bullet[i].tick += 1;
 112                         g_bullet[i].x += g_bullet[i].vx;
 113                         g_bullet[i].y += g_bullet[i].vy;
 114
 115                         checkspacebound(&g_bullet[i].x);
 116                         checkspacebound(&g_bullet[i].y);
 117
 118                         for(int j = 0; j < MAX_PLAYERS; j++)
 119                                 if(g_player[j].live)
 120                                         if(collide(g_bullet[i].x, g_bullet[i].y, 0.0001, g_player[j].x, g_player[j].y, PLAYER_SIZE))
 121                                                 if(j != g_bullet[i].owner)
 122                                                         g_player[j].live = false;
 123
 124                         if(g_bullet[i].tick > BULLET_TIME)
 125                                 g_bullet[i].live = false;
 126                 }
 127         }
 128 }