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