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         }
  50
  51         memset(rocks, 0, MAXROCKS*sizeof(struct rock));
  52
  53         for(i=1; i<MAXROCKS; i++) rocks[i].next = &rocks[i-1];
  54         free_sprites[ROCK] = SPRITE(&rocks[MAXROCKS-1]);
  55
  56         reset_rocks();
  57 }
  58
  59 enum { LEFT, RIGHT, TOP, BOTTOM };
  60
  61
  62 // compute the number of rocks/tick that should be coming from each side,
  63 // and the speed ranges of rocks coming from each side
  64 void
  65 rock_sides(float *ti, float *speed_min, float *speed_max)
  66 {
  67         float dx0,dx1, dy0,dy1;
  68         float hfactor, vfactor;
  69         int i;
  70
  71         for(i=0; i<4; i++) ti[i] = 0;
  72         for(i=0; i<4; i++) speed_min[i] = 0;
  73         for(i=0; i<4; i++) speed_max[i] = 0;
  74         hfactor = (float)nrocks/KH; vfactor = (float)nrocks/KV;
  75
  76         dx0 = -RDX - screendx; dx1 = RDX - screendx;
  77         dy0 = -RDY - screendy; dy1 = RDY - screendy;
  78
  79         if(dx0 < 0) {
  80                 speed_max[RIGHT] = -dx0;
  81                 if(dx1 < 0) {
  82                         // Rocks moving left only. So the RIGHT side of the screen
  83                         speed_min[RIGHT] = -dx1;
  84                         ti[RIGHT] = -(dx0+dx1)/2;
  85                 } else {
  86                         // Rocks moving left and right
  87                         speed_max[LEFT] = dx1;
  88                         ti[RIGHT] = -dx0/2;
  89                         ti[LEFT] = dx1/2;
  90                 }
  91         } else {
  92                 // Rocks moving right only. So the LEFT side of the screen
  93                 speed_min[LEFT] = dx0;
  94                 speed_max[LEFT] = dx1;
  95                 ti[LEFT] = (dx0+dx1)/2;
  96         }
  97         ti[LEFT] *= hfactor;
  98         ti[RIGHT] *= hfactor;
  99
 100         if(dy0 < 0) {
 101                 speed_max[BOTTOM] = -dy0;
 102                 if(dy1 < 0) {
 103                         // Rocks moving up only. So the BOTTOM of the screen
 104                         speed_min[BOTTOM] = -dy1;
 105                         ti[BOTTOM] = -(dy0+dy1)/2;
 106                 } else {
 107                         // Rocks moving up and down
 108                         speed_max[TOP] = dy1;
 109                         ti[BOTTOM] = -dy0/2;
 110                         ti[TOP] = dy1/2;
 111                 }
 112         } else {
 113                 // Rocks moving down only. so the TOP of the screen
 114                 speed_min[TOP] = dy0;
 115                 speed_max[TOP] = dy1;
 116                 ti[TOP] = (dy0+dy1)/2;
 117         }
 118         ti[TOP] *= vfactor;
 119         ti[BOTTOM] *= vfactor;
 120 }
 121
 122 float
 123 weighted_rnd_range(float min, float max) {
 124         return sqrt(min * min + frnd() * (max * max - min * min));
 125 }
 126
 127 void
 128 new_rocks(void)
 129 {
 130         int i, type;
 131         struct rock *r;
 132         float ti[4];
 133         float rmin[4];
 134         float rmax[4];
 135
 136         if(nrocks < F_ROCKS) {
 137                 nrocks_timer += t_frame;
 138                 if(nrocks_timer >= nrocks_inc_ticks) {
 139                         nrocks_timer -= nrocks_inc_ticks;
 140                         nrocks++;
 141                 }
 142         }
 143
 144         rock_sides(ti, rmin, rmax);
 145
 146         // increment timers
 147         for(i=0; i<4; i++) rtimers[i] += ti[i]*t_frame;
 148
 149         // generate rocks
 150         for(i=0; i<4; i++) {
 151                 while(rtimers[i] >= 1) {
 152                         rtimers[i] -= 1;
 153                         if(!free_sprites[ROCK]) return;  // sorry, we ran out of rocks!
 154                         r = (struct rock *) remove_sprite(&free_sprites[ROCK]);
 155                         type = urnd() % NROCKS;
 156                         *r = prototypes[type];
 157                         r->type = type;
 158                         switch(i) {
 159                                 case RIGHT:
 160                                         r->x = XSIZE;
 161                                         r->y = frnd()*(YSIZE + r->image->h);
 162
 163                                         r->dx = -weighted_rnd_range(rmin[i], rmax[i]) + screendx;
 164                                         r->dy = RDY*crnd();
 165                                         break;
 166                                 case LEFT:
 167                                         r->x = -r->image->w;
 168                                         r->y = frnd()*(YSIZE + r->image->h);
 169
 170                                         r->dx = weighted_rnd_range(rmin[i], rmax[i]) + screendx;
 171                                         r->dy = RDY*crnd();
 172                                         break;
 173                                 case BOTTOM:
 174                                         r->x = frnd()*(XSIZE + r->image->w);
 175                                         r->y = YSIZE;
 176
 177                                         r->dx = RDX*crnd();
 178                                         r->dy = -weighted_rnd_range(rmin[i], rmax[i]) + screendy;
 179                                         break;
 180                                 case TOP:
 181                                         r->x = frnd()*(XSIZE + r->image->w);
 182                                         r->y = -r->image->h;
 183
 184                                         r->dx = RDX*crnd();
 185                                         r->dy = weighted_rnd_range(rmin[i], rmax[i]) + screendy;
 186                                         break;
 187                         }
 188                         add_sprite(SPRITE(r));
 189                 }
 190         }
 191 }
 192
 193
 194 void
 195 draw_rocks(void)
 196 {
 197         int i;
 198         for(i=0; i<MAXROCKS; i++) draw_sprite(SPRITE(&rocks[i]));
 199 }
 200
 201 void
 202 blast_rocks(float x, float y, float radius)
 203 {
 204         int i;
 205         Sprite *r;
 206         float dx, dy, n;
 207
 208         for(i=0; i<MAXROCKS; i++) {
 209                 if(rocks[i].sprite_type == NONE) continue;
 210                 r = SPRITE(&rocks[i]);
 211                 if(r->x <= 0) continue;
 212
 213                 dx = r->x - x;
 214                 dy = r->y - y;
 215
 216                 n = sqrt(dx*dx + dy*dy);
 217                 if(n < radius) {
 218                         n *= 15;
 219                         r->dx += 54.0*dx/n;
 220                         r->dy += 54.0*dy/n;
 221                 }
 222         }
 223 }