src/engine/scene.h


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#pragma once

#include <vector>
#include <limits>

#include "object.h"

namespace Donut
{
    class Scene 
    {
    public:
        std::vector<Object> objs;
        glm::vec3 m_light_pos;

        Scene() 
            : m_light_pos(5.0f, 5.0f, 5.0f) { }
    
        glm::vec3 trace(Ray &ray)
        {
            float closest = std::numeric_limits<float>::infinity();
            const Object* hit_obj = nullptr;
    
            for(auto& obj : objs)
            {
                float t;

                if(obj.intersect(ray, t))
                    if(t < closest) 
                    {
                        closest = t;
                        hit_obj = &obj;
                    }
            }
            
            if(hit_obj)
            {
                glm::vec3 hit_point = ray.m_origin + ray.m_direction * closest;
                glm::vec3 normal = hit_obj->get_normal(hit_point);
                glm::vec3 light_dir = glm::normalize(m_light_pos - hit_point);
    
                float diff = std::max(glm::dot(normal, light_dir), 0.0f);
    
                Ray shadow_ray(hit_point + normal * 0.001f, light_dir);
                bool in_shadow = false;
                
                for(auto& obj : objs) 
                {
                    float t;

                    if(obj.intersect(shadow_ray, t)) 
                    {
                        in_shadow = true;
                        break;
                    }
                }
    
                glm::vec3 color = hit_obj->m_material.m_color;
                float ambient = 0.1f;
    
                if (in_shadow) 
                    return color * ambient;
                return color * (ambient + diff * 0.9f);
            }
    
            return glm::vec3(0.0f, 0.0f, 0.1f); 
        }
    };
};