brandling-safari/shared/Zone.h

#pragma once
// Deterministic safari zone layout. The server and every client call
// Zone::generate(id, seed) and get the exact same terrain, props, water,
// tall grass and landmarks, so only the zone id + seed travel over the wire.
// Everything that matters for gameplay (collision, heights, water, tall
// grass, NPC and spawn points) lives here; purely visual decoration (grass
// tufts, flowers, the tall-grass sprites themselves) is added by the client.

#include "Rng.h"

#include <glm/glm.hpp>

#include <cstdint>
#include <cmath>
#include <string>
#include <vector>

namespace bs {

// Terrain materials (client maps them to texture layers).
enum ZoneMat : uint8_t { MatGrass = 0, MatMeadow = 1, MatPath = 2, MatSand = 3, MatStone = 4, MatRidge = 5, MatPlaza = 6 };

// One placed 3D model. `radius` > 0 makes it a round obstacle.
struct ZoneProp {
    std::string model;  // model name in scenery.glb / safari.glb
    glm::vec3 pos{0.0f};
    float yaw = 0.0f;
    glm::vec3 scale{1.0f};
    float tint = 1.0f;
    float radius = 0.0f;
};

// Thin straight obstacle (fences, tent walls) as a capsule from a to b.
struct ZoneWall {
    glm::vec2 a, b;
    float halfWidth = 0.15f;
};

// Walkable wooden deck over water.
struct ZoneDock {
    glm::vec2 min, max;
    float deckY = 0.05f;
};

struct ZonePatch {
    glm::vec2 c;
    float r;
};

class Zone {
public:
    static constexpr float kWaterLevel = -0.2f;
    static constexpr float kLevelHeight = 0.5f;

    // Known ids: "meadow" (the grassy safari zone). Returns false for unknown ids.
    bool generate(const std::string& id, uint32_t seed);

    const std::string& id() const { return id_; }
    uint32_t seed() const { return seed_; }
    int width() const { return w_; }
    int depth() const { return d_; }
    bool inBounds(int x, int z) const { return x >= 0 && z >= 0 && x < w_ && z < d_; }
    int level(int x, int z) const;
    uint8_t material(int x, int z) const;
    bool tallGrassTile(int x, int z) const;

    // Same rule as hd2d::Terrain::heightAt (flat tile tops).
    float terrainHeight(float x, float z) const;
    float groundHeight(glm::vec2 p) const;  // dock deck or terrain
    bool onDock(glm::vec2 p) const;
    bool isWater(glm::vec2 p) const;        // open water (not under a dock)
    bool isDeepWater(glm::vec2 p) const;    // basin, at least 1 level below the shelf
    bool inTallGrass(glm::vec2 p) const;
    bool walkable(glm::vec2 from, glm::vec2 to, float radius = 0.28f) const;

    // Where a line cast from `from` along `dir` lands: first open water point
    // 1.6 .. 4.5 units ahead. False when there is no water in range.
    bool fishingTarget(glm::vec2 from, glm::vec2 dir, glm::vec2& bobber) const;

    bool randomTallGrassNear(Rng& rng, glm::vec2 c, float rmin, float rmax, glm::vec2& out) const;
    bool randomWater(Rng& rng, glm::vec2& out, bool deep = true) const;
    bool randomWaterNear(Rng& rng, glm::vec2 c, float rmax, glm::vec2& out) const;
    // Open grass / meadow for wandering creatures (away from the entrance plaza).
    bool randomWanderSpot(Rng& rng, glm::vec2& out) const;
    // True when a creature may stand / walk here (land creatures stay out of water).
    bool creatureWalkable(glm::vec2 p, bool water) const;

    std::vector<ZoneProp> props;
    std::vector<ZoneWall> walls;
    std::vector<ZoneDock> docks;
    std::vector<ZonePatch> tallGrassPatches;
    glm::vec2 spawn{0.0f};      // where new players appear
    float spawnYaw = 0.0f;
    glm::vec2 henry{0.0f};      // Professor Henry's post
    float henryYaw = 0.0f;
    glm::vec2 plaza{0.0f};      // entrance plaza center (no wild spawns nearby)
    glm::vec2 waterMin{0.0f}, waterMax{0.0f};  // bounds of all water tiles (+ margin)

private:
    void buildMeadow(uint32_t seed);
    void setTile(int x, int z, int level, uint8_t mat);
    void paintPath(const std::vector<glm::vec2>& pts, float halfWidth, bool clearGrass = true);
    bool blocked(glm::vec2 p, float r) const;   // overlaps a prop or wall
    bool clearForProp(glm::vec2 p, float r) const;
    void addProp(const std::string& model, glm::vec2 p, float yaw, float scale, float radius, float tint = 1.0f,
                 float yOffset = 0.0f);
    void addFence(glm::vec2 a, glm::vec2 b);

    std::string id_;
    uint32_t seed_ = 0;
    int w_ = 0, d_ = 0;
    std::vector<int> levels_;
    std::vector<uint8_t> mats_;
    std::vector<uint8_t> grass_;
};

// 0 = north (-z), pi/2 = east (+x).
inline float yawFromDir(glm::vec2 d) { return std::atan2(d.x, -d.y); }
inline glm::vec2 dirFromYaw(float yaw) { return {std::sin(yaw), -std::cos(yaw)}; }

}  // namespace bs