#include "sunlight.h"


SunLight::SunLight(Vector3d const &direction, float intensity, Color const &color) : Light(intensity, color),
                                                                                     direction(normalized(direction))
{}

Light::Illumination SunLight::illuminate(Scene const &scene, Ray const &ray) const
{
    Vector3d const target = ray.origin + (ray.length - LGT_EPS) * ray.direction;

    // Illumination object
    Illumination illum;
    illum.direction = this->direction;
    illum.distance = INFINITY;

    // Define a secondary ray from the surfa ce point to the light source.
    Ray lightRay;
    lightRay.origin = target;
    lightRay.direction = -illum.direction;
    lightRay.length = INFINITY;

    // If the target is not in shadow...
    if (!scene.findOcclusion(lightRay))
    {
        // Look at angleIntensity of light
        float angleIntensity = 1;
        // Only if normal is relevant, calculate angleIntensity
        if (ray.normal != Vector3d(0, 0, 0))
            angleIntensity = dotProduct(-ray.normal, this->direction);  // 0 if light is behind surface, 1 if light is in front of surface

        Color rayTransparency = scene.getTransparency(lightRay, INFINITY);
        illum.color = this->color * this->intensity * angleIntensity * rayTransparency;
    }
    return illum;
}