//package comp557.a5;

import javax.vecmath.Point3d;

public class BBox
{

    public Point3d max;
    public Point3d min;

    public BBox()
    {
        this.max = new Point3d(1, 1, 1);
        this.min = new Point3d(-1, -1, -1);
    }

    public boolean intersect0(Ray ray, IntersectResult result)
    {
        // Reference: http://people.csail.mit.edu/amy/papers/box-jgt.pdf

        double tmin, tmax, tymin, tymax, tzmin, tzmax;

        double invDirX = 1 / ray.viewDirection.x;
        double invDirY = 1 / ray.viewDirection.y;
        double invDirZ = 1 / ray.viewDirection.z;

        if (ray.viewDirection.x >= 1e-9)
        {
            tmin = (min.x - ray.eyePoint.x) * invDirX;
            tmax = (max.x - ray.eyePoint.x) * invDirX;
        } else
        {
            tmax = (min.x - ray.eyePoint.x) * invDirX;
            tmin = (max.x - ray.eyePoint.x) * invDirX;
        }

        if (ray.viewDirection.y >= 1e-9)
        {
            tymin = (min.y - ray.eyePoint.y) * invDirY;
            tymax = (max.y - ray.eyePoint.y) * invDirY;
        } else
        {
            tymax = (min.y - ray.eyePoint.y) * invDirY;
            tymin = (max.y - ray.eyePoint.y) * invDirY;
        }

        if ((tmin > tymax) || (tymin > tmax))
        {
            return false;
        }

        if (tymin > tmin)
        {
            tmin = tymin;
        }

        if (tymax < tmax)
        {
            tmax = tymax;
        }

        if (ray.viewDirection.z >= 1e-9)
        {
            tzmin = (min.z - ray.eyePoint.z) * invDirZ;
            tzmax = (max.z - ray.eyePoint.z) * invDirZ;
        } else
        {
            tzmax = (min.z - ray.eyePoint.z) * invDirZ;
            tzmin = (max.z - ray.eyePoint.z) * invDirZ;
        }

        if ((tmin > tzmax) || (tzmin > tmax))
        {
            return false;
        }

//        result.isIntersected = true;
//
//        if (tzmin > tmin)
//        {
//            tmin = tzmin;
//        }
//
//        if (tzmax < tmax)
//        {
//            tmax = tzmax;
//        }
//
//        if (tmin > 1e-9)
//        {
//            result.t = tmin;
//        } else
//        {
//            result.t = tmax;
//        }

        return true;
    }
    
    public boolean intersect(Ray ray, IntersectResult result)
    {
        double tmin = Double.NEGATIVE_INFINITY, tmax = Double.POSITIVE_INFINITY;

        double t1 = (min.x - ray.eyePoint.x) / ray.viewDirection.x;
        double t2 = (max.x - ray.eyePoint.x) / ray.viewDirection.x;

        double mint = t1;
        if (mint > t2) mint = t2;
        
        double maxt = t1;
        if (maxt < t2) maxt = t2;
        
        if (ray.viewDirection.x == 0)
        {
            if (ray.eyePoint.x <= min.x || ray.eyePoint.x >= max.x)
                return false;
        }
        else
        {
            if (tmin > mint) tmin = mint;
            if (tmax < maxt) tmax = maxt;
        }
        
        t1 = (min.y - ray.eyePoint.y) / ray.viewDirection.y;
        t2 = (max.y - ray.eyePoint.y) / ray.viewDirection.y;

        mint = t1;
        if (mint > t2) mint = t2;
        
        maxt = t1;
        if (maxt < t2) maxt = t2;
        
        if (ray.viewDirection.y == 0)
        {
            if (ray.eyePoint.y <= min.y || ray.eyePoint.y >= max.y)
                return false;
        }
        else
        {
            if (tmin > mint) tmin = mint;
            if (tmax < maxt) tmax = maxt;
        }
        
        t1 = (min.z - ray.eyePoint.z) / ray.viewDirection.z;
        t2 = (max.z - ray.eyePoint.z) / ray.viewDirection.z;

        mint = t1;
        if (mint > t2) mint = t2;
        
        maxt = t1;
        if (maxt < t2) maxt = t2;
        
        if (ray.viewDirection.z == 0)
        {
            if (ray.eyePoint.z <= min.z || ray.eyePoint.z >= max.z)
                return false;
        }
        else
        {
            if (tmin > mint) tmin = mint;
            if (tmax < maxt) tmax = maxt;
        }
        
        return tmax > tmin && tmax > 0.0;
    }
}