src/game/level/background.c

   1 #include <assert.h>
   2
   3 #include "game/level/background.h"
   4 #include "math/rand.h"
   5 #include "math/rect.h"
   6 #include "system/lt.h"
   7
   8 #define BACKGROUND_CHUNK_COUNT 10
   9 #define BACKGROUND_CHUNK_WIDTH 500.0f
  10 #define BACKGROUND_CHUNK_HEIGHT 500.0f
  11
  12 static void chunk_of_point(point_t p, int *x, int *y);
  13 int render_chunk(const background_t *background,
  14                  SDL_Renderer *renderer,
  15                  const camera_t *camera,
  16                  int x, int y,
  17                  color_t color,
  18                  float parallax);
  19
  20 struct background_t
  21 {
  22     lt_t *lt;
  23     color_t base_color;
  24     vec_t position;
  25 };
  26
  27 background_t *create_background(color_t base_color)
  28 {
  29     lt_t *lt = create_lt();
  30     if (lt == NULL) {
  31         return NULL;
  32     }
  33
  34     background_t *background = PUSH_LT(lt, malloc(sizeof(background_t)), free);
  35     if (background == NULL) {
  36         RETURN_LT(lt, NULL);
  37     }
  38
  39     background->base_color = base_color;
  40     background->position = vec(0.0f, 0.0f);
  41     background->lt = lt;
  42
  43     return background;
  44 }
  45
  46 void destroy_background(background_t *background)
  47 {
  48     assert(background);
  49     RETURN_LT0(background->lt);
  50 }
  51
  52 int background_render(const background_t *background,
  53                       SDL_Renderer *renderer,
  54                       const camera_t *camera)
  55 {
  56     assert(background);
  57     assert(renderer);
  58     assert(camera);
  59
  60     rect_t view_port = camera_view_port(camera, renderer);
  61
  62     int min_x = 0, min_y = 0;
  63     chunk_of_point(vec(view_port.x, view_port.y), &min_x, &min_y);
  64
  65     int max_x = 0, max_y = 0;
  66     chunk_of_point(vec(view_port.x + view_port.w,
  67                        view_port.y + view_port.h), &max_x, &max_y);
  68
  69     for (int l = 0; l < 3; ++l) {
  70         for (int x = min_x; x <= max_x; ++x) {
  71             for (int y = min_y; y <= max_y; ++y) {
  72                 if (render_chunk(background, renderer, camera, x, y, color_darker(background->base_color, 0.2f * (float)l), 1.0f - 0.2f * (float)l) < 0) {
  73                     return -1;
  74                 }
  75             }
  76         }
  77     }
  78
  79     return 0;
  80 }
  81
  82 void background_move_to(background_t *background,
  83                         vec_t position)
  84 {
  85     background->position = position;
  86 }
  87
  88 /* Private Function */
  89
  90 static void chunk_of_point(point_t p, int *x, int *y)
  91 {
  92     assert(x);
  93     assert(y);
  94     *x = (int) roundf(p.x / BACKGROUND_CHUNK_WIDTH);
  95     *y = (int) roundf(p.y / BACKGROUND_CHUNK_HEIGHT);
  96 }
  97
  98 int render_chunk(const background_t *background,
  99                  SDL_Renderer *renderer,
 100                  const camera_t *camera,
 101                  int x, int y,
 102                  color_t color,
 103                  float parallax)
 104 {
 105     srand((unsigned int)(roundf((float)x + (float)y + parallax)));
 106
 107     for (size_t i = 0; i < BACKGROUND_CHUNK_COUNT; ++i) {
 108         const float rect_x = rand_float_range((float) x * BACKGROUND_CHUNK_WIDTH,
 109                                               (float) (x + 1) * BACKGROUND_CHUNK_WIDTH);
 110         const float rect_y = rand_float_range((float) y * BACKGROUND_CHUNK_HEIGHT,
 111                                               (float) (y + 1) * BACKGROUND_CHUNK_HEIGHT);
 112         const float rect_w = rand_float_range(0.0f, BACKGROUND_CHUNK_WIDTH * 0.5f);
 113         const float rect_h = rand_float_range(0.0f, BACKGROUND_CHUNK_HEIGHT * 0.5f);
 114
 115         if (camera_fill_rect(
 116                 camera,
 117                 renderer,
 118                 rect(rect_x + background->position.x * parallax,
 119                      rect_y + background->position.y * parallax,
 120                      rect_w,
 121                      rect_h),
 122                 color) < 0) {
 123             return -1;
 124         }
 125     }
 126
 127     return 0;
 128 }