rocks.c

   1 #include <SDL_image.h>
   2 #include <math.h>
   3 #include <stdlib.h>
   4 #include <string.h>
   5
   6 #include "common.h"
   7 #include "config.h"
   8 #include "file.h"
   9 #include "globals.h"
  10 #include "mt.h"
  11 #include "rocks.h"
  12 #include "sprite.h"
  13
  14 static struct rock rocks[MAXROCKS];
  15 static struct rock prototypes[NROCKS];
  16
  17 // timers for rock generation.
  18 static float rtimers[4];
  19
  20 uint32_t nrocks = I_ROCKS;
  21 float nrocks_timer = 0;
  22 float nrocks_inc_ticks = 2*60*20/(F_ROCKS-I_ROCKS);
  23
  24 // constants for rock generation.
  25 #define KH (32*20)  // 32 s for a speed=1 rock to cross the screen horizontally.
  26 #define KV (24*20)  // 24 s for a speed=1 rock to cross the screen vertically.
  27 #define RDX 2.5  // range for rock dx values (+/-)
  28 #define RDY 2.5  // range for rock dy values (+/-)
  29
  30 void
  31 reset_rocks(void)
  32 {
  33         nrocks = I_ROCKS;
  34         nrocks_timer = 0;
  35 }
  36
  37 #define ROCK_LEN sizeof("sprites/rockXX.png")
  38
  39 void
  40 load_rocks(void)
  41 {
  42         int i;
  43         char a[ROCK_LEN];
  44
  45         for(i=0; i<NROCKS; i++) {
  46                 snprintf(a, ROCK_LEN, "sprites/rock%02d.png", i);
  47                 load_sprite(SPRITE(&prototypes[i]), a);
  48                 prototypes[i].sprite_type = ROCK;
  49                 prototypes[i].flags = MOVE|DRAW|COLLIDE;
  50         }
  51
  52         memset(rocks, 0, MAXROCKS*sizeof(struct rock));
  53
  54         for(i=1; i<MAXROCKS; i++) rocks[i].next = &rocks[i-1];
  55         free_sprites[ROCK] = SPRITE(&rocks[MAXROCKS-1]);
  56
  57         reset_rocks();
  58 }
  59
  60 enum { LEFT, RIGHT, TOP, BOTTOM };
  61
  62
  63 // compute the number of rocks/tick that should be coming from each side,
  64 // and the speed ranges of rocks coming from each side
  65 void
  66 rock_sides(float *ti, float *speed_min, float *speed_max)
  67 {
  68         float dx0,dx1, dy0,dy1;
  69         float hfactor, vfactor;
  70         int i;
  71
  72         for(i=0; i<4; i++) ti[i] = 0;
  73         for(i=0; i<4; i++) speed_min[i] = 0;
  74         for(i=0; i<4; i++) speed_max[i] = 0;
  75         hfactor = (float)nrocks/KH; vfactor = (float)nrocks/KV;
  76
  77         dx0 = -RDX - screendx; dx1 = RDX - screendx;
  78         dy0 = -RDY - screendy; dy1 = RDY - screendy;
  79
  80         if(dx0 < 0) {
  81                 speed_max[RIGHT] = -dx0;
  82                 if(dx1 < 0) {
  83                         // Rocks moving left only. So the RIGHT side of the screen
  84                         speed_min[RIGHT] = -dx1;
  85                         ti[RIGHT] = -(dx0+dx1)/2;
  86                 } else {
  87                         // Rocks moving left and right
  88                         speed_max[LEFT] = dx1;
  89                         ti[RIGHT] = -dx0/2;
  90                         ti[LEFT] = dx1/2;
  91                 }
  92         } else {
  93                 // Rocks moving right only. So the LEFT side of the screen
  94                 speed_min[LEFT] = dx0;
  95                 speed_max[LEFT] = dx1;
  96                 ti[LEFT] = (dx0+dx1)/2;
  97         }
  98         ti[LEFT] *= hfactor;
  99         ti[RIGHT] *= hfactor;
 100
 101         if(dy0 < 0) {
 102                 speed_max[BOTTOM] = -dy0;
 103                 if(dy1 < 0) {
 104                         // Rocks moving up only. So the BOTTOM of the screen
 105                         speed_min[BOTTOM] = -dy1;
 106                         ti[BOTTOM] = -(dy0+dy1)/2;
 107                 } else {
 108                         // Rocks moving up and down
 109                         speed_max[TOP] = dy1;
 110                         ti[BOTTOM] = -dy0/2;
 111                         ti[TOP] = dy1/2;
 112                 }
 113         } else {
 114                 // Rocks moving down only. so the TOP of the screen
 115                 speed_min[TOP] = dy0;
 116                 speed_max[TOP] = dy1;
 117                 ti[TOP] = (dy0+dy1)/2;
 118         }
 119         ti[TOP] *= vfactor;
 120         ti[BOTTOM] *= vfactor;
 121 }
 122
 123 float
 124 weighted_rnd_range(float min, float max) {
 125         return sqrt(min * min + frnd() * (max * max - min * min));
 126 }
 127
 128 void
 129 new_rocks(void)
 130 {
 131         int i, type;
 132         struct rock *r;
 133         float ti[4];
 134         float rmin[4];
 135         float rmax[4];
 136
 137         if(nrocks < F_ROCKS) {
 138                 nrocks_timer += t_frame;
 139                 if(nrocks_timer >= nrocks_inc_ticks) {
 140                         nrocks_timer -= nrocks_inc_ticks;
 141                         nrocks++;
 142                 }
 143         }
 144
 145         rock_sides(ti, rmin, rmax);
 146
 147         // increment timers
 148         for(i=0; i<4; i++) rtimers[i] += ti[i]*t_frame;
 149
 150         // generate rocks
 151         for(i=0; i<4; i++) {
 152                 while(rtimers[i] >= 1) {
 153                         rtimers[i] -= 1;
 154                         if(!free_sprites[ROCK]) return;  // sorry, we ran out of rocks!
 155                         r = (struct rock *) remove_sprite(&free_sprites[ROCK]);
 156                         type = urnd() % NROCKS;
 157                         *r = prototypes[type];
 158                         r->type = type;
 159                         switch(i) {
 160                                 case RIGHT:
 161                                         r->x = XSIZE;
 162                                         r->y = frnd()*(YSIZE + r->image->h);
 163
 164                                         r->dx = -weighted_rnd_range(rmin[i], rmax[i]) + screendx;
 165                                         r->dy = RDY*crnd();
 166                                         break;
 167                                 case LEFT:
 168                                         r->x = -r->image->w;
 169                                         r->y = frnd()*(YSIZE + r->image->h);
 170
 171                                         r->dx = weighted_rnd_range(rmin[i], rmax[i]) + screendx;
 172                                         r->dy = RDY*crnd();
 173                                         break;
 174                                 case BOTTOM:
 175                                         r->x = frnd()*(XSIZE + r->image->w);
 176                                         r->y = YSIZE;
 177
 178                                         r->dx = RDX*crnd();
 179                                         r->dy = -weighted_rnd_range(rmin[i], rmax[i]) + screendy;
 180                                         break;
 181                                 case TOP:
 182                                         r->x = frnd()*(XSIZE + r->image->w);
 183                                         r->y = -r->image->h;
 184
 185                                         r->dx = RDX*crnd();
 186                                         r->dy = weighted_rnd_range(rmin[i], rmax[i]) + screendy;
 187                                         break;
 188                         }
 189                         add_sprite(SPRITE(r));
 190                 }
 191         }
 192 }
 193
 194
 195 void
 196 draw_rocks(void)
 197 {
 198         int i;
 199         for(i=0; i<MAXROCKS; i++) draw_sprite(SPRITE(&rocks[i]));
 200 }
 201
 202 void
 203 blast_rocks(float x, float y, float radius)
 204 {
 205         int i;
 206         Sprite *r;
 207         float dx, dy, n;
 208
 209         for(i=0; i<MAXROCKS; i++) {
 210                 if(!rocks[i].flags) continue;
 211                 r = SPRITE(&rocks[i]);
 212                 if(r->x <= 0) continue;
 213
 214                 dx = r->x - x;
 215                 dy = r->y - y;
 216
 217                 n = sqrt(dx*dx + dy*dy);
 218                 if(n < radius) {
 219                         n *= 15;
 220                         r->dx += 54.0*dx/n;
 221                         r->dy += 54.0*dy/n;
 222                 }
 223         }
 224 }