feat: add 4 biomes

src/tools/math_tools.cpp

@@ -1,6 +1,13 @@
 #include <Cubed/tools/math_tools.hpp>
 
 #include <glm/gtc/type_ptr.hpp>
+
+#include <cmath>
+
+#include <Cubed/config.hpp>
+#include <Cubed/gameplay/chunk_status.hpp>
+#include <Cubed/tools/perlin_noise.hpp>
+
 namespace Math {
     void extract_frustum_planes(const glm::mat4& mvp_matrix, std::vector<glm::vec4>& planes) {
         if (planes.size() != 6) {
@@ -26,4 +33,46 @@ namespace Math {
             p = glm::normalize(p);
         }
     }
+
+    int get_interpolated_height(float world_x, float world_z, float biome_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_mountain = weight(temp, humid, 0.25f, 0.25f);
+        float w_plain    = weight(temp, humid, 0.25f, 0.75f);
+        float w_desert   = weight(temp, humid, 0.75f, 0.25f);
+        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);
+        w_plain    = std::pow(w_plain,    pow_n);
+        w_desert   = std::pow(w_desert,   pow_n);
+        w_forest   = std::pow(w_forest,   pow_n);
+
+        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);
+    }
 }