Interaction.hpp

#pragma once
#define GLM_ENABLE_EXPERIMENTAL
#include <glm/glm.hpp>
#include <glm/gtx/intersect.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <memory>

class Material;
class Medium;
class PhaseFunction;
class Light;

struct GeometricInteraction{
    glm::vec3 p = { 0,0,0 };
    glm::vec3 n = { 0,0,0 };//geometric normal
    std::shared_ptr<Medium> medium = nullptr;

    bool isSurfaceInteraction() const{
        return n != glm::vec3(0, 0, 0);
    }

    bool isMediumInteraction() const{
        return !isSurfaceInteraction();
    }

    std::shared_ptr<Medium> getMedium(const glm::vec3& dir) const{
        if(glm::dot(dir, n) < 0)return medium;//going into surface
        return nullptr;
    }
    GeometricInteraction() = default;
    GeometricInteraction(const glm::vec3& point, const glm::vec3& geometric_normal, const std::shared_ptr<Medium>& interactionMedium = nullptr) : p { point }, n { geometric_normal }, medium(interactionMedium){

    }
};

struct SurfaceInteraction : public GeometricInteraction{
    SurfaceInteraction(const glm::vec3& point, const glm::vec3& geometric_normal, const glm::vec2& uvCoord, const std::shared_ptr<Medium>& interactionMedium = nullptr) : GeometricInteraction { point,geometric_normal,interactionMedium }, uv { uvCoord }{

    }

    SurfaceInteraction() = default;
    SurfaceInteraction(const GeometricInteraction& interaction) : GeometricInteraction { interaction }{

    }
    glm::vec2 uv = { 0,0 };
    float t = 0;//we dont need t if we have point? t = glm::length(ray)
    glm::vec3 ns = { 0,0,0 };
    std::shared_ptr<Material> mat = nullptr;
    glm::vec3 tangent = { 0,0,0 };
    std::shared_ptr<Light> AreaLight = nullptr;
};

struct MediumInteraction : public GeometricInteraction{
    MediumInteraction(const glm::vec3& point, const glm::vec3& geometric_normal, const std::shared_ptr<Medium>& interactionMedium, const std::shared_ptr<PhaseFunction>& phaseFunc) : GeometricInteraction { point,geometric_normal,interactionMedium }, phaseFunction { phaseFunc }{

    }

    MediumInteraction() = default;

    bool isValid() const{
        return phaseFunction != nullptr;
    }
    std::shared_ptr<PhaseFunction> phaseFunction = nullptr;
};