1 files changed, 68 insertions, 0 deletions
diff --git a/generator.c b/generator.c
new file mode 100644
index 0000000..6cf3ad4
--- /dev/null
+++ b/generator.c
@@ -0,0 +1,68 @@
+#include <SDL.h>
+
+#include "world.h"
+#include "random.h"
+
+#define MAX_INFLUENCE 10
+#define SPARSITY 40.0
+#define CAVERNITY 3
+
+#define SURFACE_COLLECTIBLE_RARITY 70
+
+void generate_chunk(world *w, chunk *c) {
+	SDL_memset(c->tiles, TILE_EMPTY, sizeof(c->tiles));
+	if (c->pos.y < 0) return;
+
+	static float noise_params[CHUNK_DIM * CHUNK_DIM];
+	SDL_memset(noise_params, 0, sizeof(noise_params));
+
+	for (int i = 0; i < CHUNK_DIM * CHUNK_DIM; i++) {
+		if (rand_int() % CAVERNITY == 0) {
+			noise_params[i] =
+				SDL_pow(rand_float(), SPARSITY) * MAX_INFLUENCE;
+		}
+	}
+
+	for (int y = 0; y < CHUNK_DIM; y++) {
+		for (int x = 0; x < CHUNK_DIM; x++) {
+			float influence = noise_params[tile_index((SDL_Point) {x, y})];
+			if (c->pos.y == 0) {
+				if (y < 96) influence = 0;
+				else influence *= 1.8;
+			}
+
+			int boundary = influence + 0.5;
+			int min_x = SDL_max(x - boundary, 0);
+			int max_x = SDL_min(x + boundary, CHUNK_DIM - 1);
+			int min_y = SDL_max(y - boundary, 0);
+			int max_y = SDL_min(y + boundary, CHUNK_DIM - 1);
+
+			for (int iy = min_y; iy <= max_y; iy++) {
+				for (int ix = min_x; ix <= max_x; ix++) {
+					int dx = ix - x;
+					int dy = iy - y;
+					if (dx * dx + dy * dy <= influence * influence) {
+						if (dx != 0 || dy != 0 || influence > 0.5) {
+							c->tiles[
+								tile_index((SDL_Point) {ix, iy})] = TILE_WALL;
+						}
+					}
+				}
+			}
+		}
+	}
+
+	int rarity = c->pos.x != 0 && c->pos.x != -1 ?
+		SURFACE_COLLECTIBLE_RARITY : 8;
+	if (c->pos.y == 0) {
+		for (int x = 0; x < CHUNK_DIM; x++) {
+			if (rand_int() % rarity == 0) {
+				int y = 0;
+
+				while (!is_solid(c->tiles[tile_index((SDL_Point) {x, y + 1})]))
+					y++;
+				c->tiles[tile_index((SDL_Point) {x, y})] = rand_int() % TILE_LIGHT;
+			}
+		}
+	}
+}