LSystem.h

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#pragma once
#include "common/Export.h"
 
 
#include <cstdint>
#include <string>
#include <utility>
#include <vector>
 
namespace eve::procgen {
 
class PointSet;
 
struct LSystemSegment {
    float sx = 0.f, sy = 0.f, sz = 0.f;  // start
    float ex = 0.f, ey = 0.f, ez = 0.f;  // end
    float r0 = 0.f, r1 = 0.f;            // radius at start / end
    int   depth = 0;                     // bracket nesting at draw time
    bool  leaf = false;                  // foliage marker instead of a limb
    float leafSize = 0.f;                // foliage card size for leaf segments
    float dx = 0.f, dy = 0.f, dz = 0.f;  // turtle heading at a leaf marker
};
 
struct LSystemResult {
    std::vector<LSystemSegment> segments;
    std::string                 derivation;
    int                         leafCount = 0;
};
 
class EVENGINE_API_DOMAINS LSystem {
public:
    LSystem();
 
    void setAxiom(const std::string& axiom);
    void addRule(char symbol, const std::string& production);
    void addRules(char symbol, const std::vector<std::string>& productions, const std::vector<float>& weights);
    void clearRules();
 
    void setAngle(float degrees);
    void setStep(float step);
    void setIterations(int iterations);
    void setSeed(uint32_t seed);
    void setInitialHeading(float x, float y, float z);
    void setBranchRadius(float radius);
    void setBranchRadiusFalloff(float factor);
    void setLeafSize(float size);
    void setLeafSymbols(const std::string& symbols);
    void setTropism(float x, float y, float z);
 
    uint32_t getSeed() const;
    int      getIterations() const;
 
    std::string derive() const;
    void generate(LSystemResult& out) const;
    void toPointSet(PointSet& out) const;
 
private:
    struct Vec3 {
        float x = 0.f, y = 0.f, z = 0.f;
    };
    struct TurtleState {
        Vec3  pos, heading, up;
        int   depth = 0;
    };
    using Rule = std::pair<std::string, float>;  // production, weight
 
    Vec3   rotate(const Vec3& v, const Vec3& axis, float angle) const;
    void   orthonormalize(Vec3& heading, Vec3& up) const;
    void   interpret(const std::string& word, LSystemResult& out) const;
 
    std::string                  axiom_;
    std::vector<Rule>            rules_[256];
    float       angleDeg_    = 25.f;
    float       step_        = 1.f;
    int         iterations_  = 5;
    uint32_t    seed_        = 1;
    Vec3        heading0_    = {0.f, 1.f, 0.f};
    float       branchRadius_ = 0.1f;
    float       radiusFalloff_ = 0.6f;
    float       leafSize_    = 0.4f;
    bool        leafChars_[256] = {};
    Vec3        tropism_     = {0.f, 0.f, 0.f};
};
 
}  // namespace eve::procgen