simpleraytracer_v1_0.zip raysphere.cpp

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/*===================================================================

digital liberation front 2002

_______ ______ _______
/______/\ |______| /\______\
| \ \ | | / / |
| \| | | |/ |
|_____ \ | |_ / ______|
____| | | |_|| |_____
|____| |________||____|

Code by Nicholas Chapman[/ Ono-Sendai]
nickamy@paradise.net.nz

You may use this code for any non-commercial project,
as long as you do not remove this description.

You may not use this code for any commercial project.
====================================================================*/
#include "raysphere.h"

#include "ray.h"

//returns neg num if object not hit by the ray
float RaySphere::getDistanceUntilHit(const Ray&amt; ray) const
{
const Vec3 raystarttosphere = this->centerpos - ray.startpos;

const float dist_to_rayclosest = dotProduct(raystarttosphere, ray.unitdir);

//-----------------------------------------------------------------
//check if center of sphere lies behind ray startpos (in dir of ray)
//-----------------------------------------------------------------
if(dist_to_rayclosest < 0.0f)//will think of rays as having infinite length || q_closest > ray.length)
return -666.0f;

const float sph_cen_to_ray_closest_len2 = raystarttosphere.length2() -
dist_to_rayclosest*dist_to_rayclosest;

//-----------------------------------------------------------------
//ray has missed sphere?
//-----------------------------------------------------------------
if(sph_cen_to_ray_closest_len2 > this->radius_squared)
return -666.0f;

//ray has hit sphere...

return dist_to_rayclosest - sqrt(this->radius_squared - sph_cen_to_ray_closest_len2);
}

const Vec3 RaySphere::getNormalForPos(const Vec3&amt; point) const
{
return (point - centerpos) * recip_radius;
}