src/game/level/explosion.c

   1 #include <SDL.h>
   2 #include "system/stacktrace.h"
   3
   4 #include "explosion.h"
   5 #include "math/rand.h"
   6 #include "system/lt.h"
   7 #include "system/nth_alloc.h"
   8
   9 #define EXPLOSION_PIECE_COUNT 20
  10 #define EXPLOSION_PIECE_SIZE 20.0f
  11
  12 typedef struct Piece {
  13     Point position;
  14     float angle;
  15     float angle_velocity;
  16     Vec direction;
  17     Triangle body;
  18 } Piece;
  19
  20 struct Explosion
  21 {
  22     Lt *lt;
  23
  24     Vec position;
  25     Color color;
  26     float duration;
  27     float time_passed;
  28     Piece *pieces;
  29 };
  30
  31 Explosion *create_explosion(Color color,
  32                             float duration)
  33 {
  34     Lt *lt = create_lt();
  35
  36     Explosion *explosion = PUSH_LT(lt, nth_calloc(1, sizeof(Explosion)), free);
  37     if (explosion == NULL) {
  38         RETURN_LT(lt, NULL);
  39     }
  40
  41     explosion->lt = lt;
  42     explosion->position = vec(0.0f, 0.0f);
  43     explosion->color = color;
  44     explosion->duration = duration;
  45     explosion->time_passed = duration;
  46
  47     explosion->pieces = PUSH_LT(lt, nth_calloc(1, sizeof(Piece) * EXPLOSION_PIECE_COUNT), free);
  48     if (explosion->pieces == NULL) {
  49         RETURN_LT(lt, NULL);
  50     }
  51
  52     return explosion;
  53 }
  54
  55 void destroy_explosion(Explosion *explosion)
  56 {
  57     trace_assert(explosion);
  58     RETURN_LT0(explosion->lt);
  59 }
  60
  61 int explosion_render(const Explosion *explosion,
  62                      Camera *camera)
  63 {
  64     trace_assert(explosion);
  65     trace_assert(camera);
  66
  67     for (size_t i = 0; i < EXPLOSION_PIECE_COUNT; ++i) {
  68         Color color = explosion->color;
  69         color.a = fminf(1.0f, 4.0f - (float) explosion->time_passed / (float) explosion->duration * 4.0f);
  70
  71         if (camera_fill_triangle(
  72                 camera,
  73                 triangle_mat3x3_product(
  74                     explosion->pieces[i].body,
  75                     mat3x3_product(
  76                         trans_mat(explosion->pieces[i].position.x,
  77                                   explosion->pieces[i].position.y),
  78                         rot_mat(explosion->pieces[i].angle))),
  79                 color) < 0) {
  80             return -1;
  81         }
  82     }
  83
  84     return 0;
  85 }
  86
  87 int explosion_update(Explosion *explosion,
  88                      float delta_time)
  89 {
  90     trace_assert(explosion);
  91     trace_assert(delta_time > 0.0f);
  92
  93     if (explosion_is_done(explosion)) {
  94         return 0;
  95     }
  96
  97     explosion->time_passed = explosion->time_passed + delta_time;
  98
  99     for (size_t i = 0; i < EXPLOSION_PIECE_COUNT; ++i) {
 100         vec_add(
 101             &explosion->pieces[i].position,
 102             vec_scala_mult(
 103                 explosion->pieces[i].direction,
 104                 delta_time));
 105         explosion->pieces[i].angle = fmodf(
 106             explosion->pieces[i].angle + explosion->pieces[i].angle_velocity * delta_time,
 107             2.0f * PI);
 108     }
 109
 110     return 0;
 111 }
 112
 113 int explosion_is_done(const Explosion *explosion)
 114 {
 115     trace_assert(explosion);
 116     return explosion->time_passed >= explosion->duration;
 117 }
 118
 119 void explosion_start(Explosion *explosion,
 120                      Vec position)
 121 {
 122     explosion->position = position;
 123     explosion->time_passed = 0;
 124
 125     for (size_t i = 0; i < EXPLOSION_PIECE_COUNT; ++i) {
 126         explosion->pieces[i].position = explosion->position;
 127         explosion->pieces[i].angle = rand_float(2 * PI);
 128         explosion->pieces[i].angle_velocity = rand_float(8.0f);
 129         explosion->pieces[i].body = random_triangle(EXPLOSION_PIECE_SIZE);
 130         explosion->pieces[i].direction = vec_from_polar(
 131             rand_float_range(-PI, 0.0f),
 132             rand_float_range(100.0f, 300.0f));
 133     }
 134 }