refactor: separate biome declaration and definition

src/gameplay/biome.cpp

@@ -0,0 +1,134 @@
+#include <Cubed/gameplay/biome.hpp>
+#include <Cubed/tools/cubed_assert.hpp>
+#include <Cubed/tools/log.hpp>
+#include <Cubed/tools/perlin_noise.hpp>
+
+#include <cmath>
+#include <unordered_map>
+
+std::string get_biome_str(Biome biome) {
+    std::string str;
+    using enum Biome;
+    switch (biome) {
+        case PLAIN:
+            str = "Plain";
+            break;
+        case FOREST:
+            str = "Forest";
+            break;
+        case DESERT:
+            str = "Desert";
+            break;
+        case MOUNTAIN:
+            str = "Mountain";
+            break;
+    }
+    return str;
+};
+
+Biome get_biome_from_noise(float temp, float humid) {
+    auto weight = [](float t, float h, float ct, float ch) -> float {
+            float dt = t - ct;
+            float dh = h - ch;
+            float dist = std::sqrt(dt*dt + dh*dh);
+            return std::max(0.0f, 0.5f - dist); 
+        };
+    float w_m = weight(temp, humid, 0.25f, 0.15f);
+    float w_p = weight(temp, humid, 0.50f, 0.40f);
+    float w_d = weight(temp, humid, 0.75f, 0.15f);
+    float w_f = weight(temp, humid, 0.75f, 0.75f);
+    w_m = pow(w_m, 8); w_p = pow(w_p, 8); w_d = pow(w_d, 8); w_f = pow(w_f, 8);
+    if (w_m >= w_p && w_m >= w_d && w_m >= w_f) return Biome::MOUNTAIN;
+    if (w_p >= w_m && w_p >= w_d && w_p >= w_f) return Biome::PLAIN;
+    if (w_d >= w_m && w_d >= w_p && w_d >= w_f) return Biome::DESERT;
+    return Biome::FOREST;
+}
+
+std::array<float, 3> get_noise_frequencies_for_biome(Biome biome) {
+    using enum Biome;
+    switch (biome) {
+        case PLAIN:
+            return {0.003f, 0.010f, 0.020f};
+        case FOREST:
+            return {0.004f, 0.012f, 0.022f};
+        case DESERT:
+            return {0.003f, 0.010f, 0.020f};
+        case MOUNTAIN:
+            return {0.006f, 0.015f, 0.030f};
+    }
+    Logger::warn("Unknown Biome");
+    return {0.003f, 0.015f, 0.06f};
+}
+
+BiomeHeightRange get_biome_height_range(Biome biome) {
+    using enum Biome;
+    switch (biome) {
+        case PLAIN:
+            return {62, 8};
+        case FOREST:
+            return {64, 12};
+        case DESERT:
+            return {61, 12};
+        case MOUNTAIN:
+            return {70, 70};
+    }
+    Logger::warn("Unknown Biome");
+    return {62, 4};
+}
+
+Biome safe_int_to_biome(int x) {
+    using enum Biome;
+    static const std::unordered_map<int, Biome> INT_TO_BIOME_MAP {
+        {0, PLAIN},
+        {1, FOREST},
+        {2, DESERT},
+        {3, MOUNTAIN}
+    };
+
+    auto it = INT_TO_BIOME_MAP.find(x);
+    CUBED_ASSERT_MSG(it != INT_TO_BIOME_MAP.end(), ":Can't Find");    
+    return it->second;
+}
+
+int get_interpolated_height(float world_x, float world_z, float temp, float humid) {
+        
+    auto weight = [](float t, float h, float ct, float ch) -> float {
+        float dt = t - ct;
+        float dh = h - ch;
+        float dist = std::sqrt(dt*dt + dh*dh);
+        return std::max(0.0f, 0.5f - dist); 
+    };
+
+    float w_mountain = weight(temp, humid, 0.25f, 0.15f);
+    float w_plain    = weight(temp, humid, 0.50f, 0.40f);
+    float w_desert   = weight(temp, humid, 0.75f, 0.15f);
+    float w_forest   = weight(temp, humid, 0.75f, 0.75f);
+    // adjust transitions between chunks
+    float pow_n = 8.0f; // the larger n is, the purer the biome
+    w_mountain = std::pow(w_mountain, pow_n) * MOUNTAIN_FREQ;
+    w_plain    = std::pow(w_plain,    pow_n) * PLAIN_FREQ;
+    w_desert   = std::pow(w_desert,   pow_n) * DESERT_FREQ;
+    w_forest   = std::pow(w_forest,   pow_n) * FOREST_FREQ;
+
+    float total = w_mountain + w_plain + w_desert + w_forest;
+    w_mountain /= total; w_plain /= total; w_desert /= total; w_forest /= total;
+
+    auto sample_height = [&](Biome b) -> float {
+        auto range = get_biome_height_range(b);
+        auto [f1, f2, f3] = get_noise_frequencies_for_biome(b);
+        float n =
+            1.00f * PerlinNoise::noise(world_x * f1, 0.5f, world_z * f1) +
+            0.50f * PerlinNoise::noise(world_x * f2, 0.5f, world_z * f2) +
+            0.25f * PerlinNoise::noise(world_x * f3, 0.5f, world_z * f3);
+        n /= 1.75f;
+        return range.base_y + n * range.amplitude;
+    };
+
+    float h = w_mountain * sample_height(Biome::MOUNTAIN)
+            + w_plain    * sample_height(Biome::PLAIN)
+            + w_desert   * sample_height(Biome::DESERT)
+            + w_forest   * sample_height(Biome::FOREST);
+    return static_cast<int>(h);
+}
+
+