src/game/level/explosion.c

   1 #include <SDL2/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     if (lt == NULL) {
  36         return NULL;
  37     }
  38
  39     Explosion *explosion = PUSH_LT(lt, nth_calloc(1, sizeof(Explosion)), free);
  40     if (explosion == NULL) {
  41         RETURN_LT(lt, NULL);
  42     }
  43
  44     explosion->lt = lt;
  45     explosion->position = vec(0.0f, 0.0f);
  46     explosion->color = color;
  47     explosion->duration = duration;
  48     explosion->time_passed = duration;
  49
  50     explosion->pieces = PUSH_LT(lt, nth_calloc(1, sizeof(Piece) * EXPLOSION_PIECE_COUNT), free);
  51     if (explosion->pieces == NULL) {
  52         RETURN_LT(lt, NULL);
  53     }
  54
  55     return explosion;
  56 }
  57
  58 void destroy_explosion(Explosion *explosion)
  59 {
  60     trace_assert(explosion);
  61     RETURN_LT0(explosion->lt);
  62 }
  63
  64 int explosion_render(const Explosion *explosion,
  65                      Camera *camera)
  66 {
  67     trace_assert(explosion);
  68     trace_assert(camera);
  69
  70     for (size_t i = 0; i < EXPLOSION_PIECE_COUNT; ++i) {
  71         Color color = explosion->color;
  72         color.a = fminf(1.0f, 4.0f - (float) explosion->time_passed / (float) explosion->duration * 4.0f);
  73
  74         if (camera_fill_triangle(
  75                 camera,
  76                 triangle_mat3x3_product(
  77                     explosion->pieces[i].body,
  78                     mat3x3_product(
  79                         trans_mat(explosion->pieces[i].position.x,
  80                                   explosion->pieces[i].position.y),
  81                         rot_mat(explosion->pieces[i].angle))),
  82                 color) < 0) {
  83             return -1;
  84         }
  85     }
  86
  87     return 0;
  88 }
  89
  90 int explosion_update(Explosion *explosion,
  91                      float delta_time)
  92 {
  93     trace_assert(explosion);
  94     trace_assert(delta_time > 0.0f);
  95
  96     if (explosion_is_done(explosion)) {
  97         return 0;
  98     }
  99
 100     explosion->time_passed = explosion->time_passed + delta_time;
 101
 102     for (size_t i = 0; i < EXPLOSION_PIECE_COUNT; ++i) {
 103         vec_add(
 104             &explosion->pieces[i].position,
 105             vec_scala_mult(
 106                 explosion->pieces[i].direction,
 107                 delta_time));
 108         explosion->pieces[i].angle = fmodf(
 109             explosion->pieces[i].angle + explosion->pieces[i].angle_velocity * delta_time,
 110             2.0f * PI);
 111     }
 112
 113     return 0;
 114 }
 115
 116 int explosion_is_done(const Explosion *explosion)
 117 {
 118     trace_assert(explosion);
 119     return explosion->time_passed >= explosion->duration;
 120 }
 121
 122 void explosion_start(Explosion *explosion,
 123                      Vec position)
 124 {
 125     explosion->position = position;
 126     explosion->time_passed = 0;
 127
 128     for (size_t i = 0; i < EXPLOSION_PIECE_COUNT; ++i) {
 129         explosion->pieces[i].position = explosion->position;
 130         explosion->pieces[i].angle = rand_float(2 * PI);
 131         explosion->pieces[i].angle_velocity = rand_float(8.0f);
 132         explosion->pieces[i].body = random_triangle(EXPLOSION_PIECE_SIZE);
 133         explosion->pieces[i].direction = vec_from_polar(
 134             rand_float_range(-PI, 0.0f),
 135             rand_float_range(100.0f, 300.0f));
 136     }
 137 }