smoother type selection during chunk generation

[blank.git] / src / world / BlockType.hpp

diff --git a/src/world/BlockType.hpp b/src/world/BlockType.hpp
index 3ca170a200ba65367ff604bfbada3645456714b1..f1b887d3eabc56e998fd64917c8a661df9df52b9 100644 (file)
--- a/src/world/BlockType.hpp
+++ b/src/world/BlockType.hpp
@@ -9,6 +9,7 @@
 #include "../model/Shape.hpp"
 
 #include <glm/glm.hpp>
+#include <limits>
 #include <vector>
 
 
@@ -58,20 +59,58 @@ struct BlockType {
        // generation properties
        /// whether to use this block in generation at all
        bool generate;
+
        // min/mid/max points for the respective properties
        // should all be in the (-1,1) range
-       float min_solidity;
-       float mid_solidity;
-       float max_solidity;
-       float min_humidity;
-       float mid_humidity;
-       float max_humidity;
-       float min_temperature;
-       float mid_temperature;
-       float max_temperature;
-       float min_richness;
-       float mid_richness;
-       float max_richness;
+       class Distribution {
+
+       public:
+               Distribution(float min, float mid, float max)
+               : xmin(min), xmid(mid), xmax(max) { Update(); }
+
+               bool Valid(float x) const noexcept {
+                       return x >= xmin && x <= xmax;
+               }
+               float Map(float x) const noexcept {
+                       // previous algo as was used by Generator
+                       //return 4.0f - ((x - xmid) * (x - xmid));
+
+                       // linear mapping of [min,mid,max] to [-1,0,1]
+                       x -= xmid;
+                       x *= (x < 0) ? inv_neg : inv_pos;
+
+                       // smoothing: x^4 - 2x^2 + 1
+                       x *= x;
+                       return x * x - 2.0f * x + 1.0f;
+               }
+
+               void Min(float m) noexcept { xmin = m; Update(); }
+               float Min() const noexcept { return xmin; }
+               void Mid(float m) noexcept { xmid = m; Update(); }
+               float Mid() const noexcept { return xmid; }
+               void Max(float m) noexcept { xmax = m; Update(); }
+               float Max() const noexcept { return xmax; }
+
+       private:
+               void Update() {
+                       float abs_min = std::abs(xmin - xmid);
+                       inv_neg = abs_min < std::numeric_limits<float>::epsilon() ? 0.0f : 1.0f / abs_min;
+                       float abs_max = std::abs(xmax - xmid);
+                       inv_pos = abs_max < std::numeric_limits<float>::epsilon() ? 0.0f : 1.0f / abs_max;
+               }
+
+               float xmin;
+               float xmid;
+               float xmax;
+               float inv_neg;
+               float inv_pos;
+
+       };
+
+       Distribution solidity;
+       Distribution humidity;
+       Distribution temperature;
+       Distribution richness;
        /// commonness factor, random chance is multiplied by this
        float commonness;