HitscanEffect.hpp

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#pragma once
 
#include "ecs/components/Projectile.hpp"
#include "particles/ParticleTypes.hpp"
 
#include <glm/glm.hpp>
#include <vector>

class HitscanEffect
{
public:
    void update(float dt, glm::vec3 camForward);

    void spawn(glm::vec3 origin, glm::vec3 hitPos, WeaponType wt, glm::vec3 camForward);

    [[nodiscard]] const ArcVertex* arcData() const { return arcVerts_.data(); }

    [[nodiscard]] uint32_t arcCount() const { return static_cast<uint32_t>(arcVerts_.size()); }

    [[nodiscard]] uint32_t activeBeamCount() const;
 
    // Legacy API compatibility -- beam quad pool not used; everything is arc verts.
    [[nodiscard]] const HitscanBeam* beamData() const { return nullptr; }
    [[nodiscard]] uint32_t beamCount() const { return 0; }
 
private:
    // Tuning constants
    static constexpr int k_maxBeams = 4;
    static constexpr int k_bezierSegs = 32; 
    static constexpr int k_branchSegs = 7;  
    static constexpr int k_maxBranches = 5;
    static constexpr float k_beamLifetime = 0.22f;
    static constexpr float k_interpDuration = 0.08f; 
 
    // Internal data structures

    struct Branch
    {
        float tStart; 
        float length; 
        float angle;  
        float seed;   
    };

    struct ReturnStroke
    {
        float fireAt = 0.f; 
        float seed = 0.f;
        bool fired = false;
    };

    struct BezierBeam
    {
        glm::vec3 origin, hitPos;
 
        // Cubic Bezier CPs -- interpolated from prev -> curr over k_interpDuration.
        glm::vec3 cp1Curr, cp2Curr;
        glm::vec3 cp1Prev, cp2Prev;
        float interpT = 1.f;
 
        // fBm animation time (accumulates each frame).
        float time = 0.f;
        float noiseSeed = 0.f; 
        float warpSeed = 0.f;  
 
        Branch branches[k_maxBranches]{};
        int branchCount = 0;
        float branchTimer = 0.f;
        static constexpr float k_branchRetime = 0.045f; 
 
        ReturnStroke returnStrokes[3]{};
 
        float lifetime = 0.f;
        bool active = false;
    };
 
    BezierBeam beams_[k_maxBeams]{};
    std::vector<ArcVertex> arcVerts_;
 
    // Helpers

    static glm::vec3 evalBezier(glm::vec3 p0, glm::vec3 p1, glm::vec3 p2, glm::vec3 p3, float t);

    static glm::vec3 evalBezierTangent(glm::vec3 p0, glm::vec3 p1, glm::vec3 p2, glm::vec3 p3, float t);

    static void randomizeCP(glm::vec3 origin, glm::vec3 hitPos, glm::vec3 camForward, glm::vec3& cp1, glm::vec3& cp2);

    static void rerandomizeBranches(BezierBeam& beam, glm::vec3 camForward);

    void appendArcStrip(const std::vector<glm::vec3>& pts, float radius, glm::vec4 color, glm::vec3 camForward);
};