source: GTP/trunk/App/Demos/Illum/pathmap/Sphere.cpp @ 2197

#include "dxstdafx.h"
#include "Sphere.hpp"

bool Sphere::intersectBackSide (const Ray& ray, float& depth, float rayMin, float rayMax)
{
        lastTestedRayId = ray.id;
        lastTestedRayResult.isIntersect = false;
        Vector diff = (ray.origin - centre);
        float b = 2.0f * (ray.dir * diff);
        float c = diff * diff - radius * radius;

        float discriminant = b * b - 4.0f * c;
        if(discriminant < 0.0f)
                return false;
        else
        {
                depth = (-b + sqrtf(discriminant)) * 0.5f;
                lastTestedRayResult.isIntersect = true;
                lastTestedRayResult.depth               = depth;
                lastTestedRayResult.material    = this->material;
                if(ray.isShadowRay) return true;
                lastTestedRayResult.point = ray.origin + ray.dir * depth;
                lastTestedRayResult.normal.setDifference(lastTestedRayResult.point, centre);
                lastTestedRayResult.normal *= 1.0f / radius;
                lastTestedRayResult.object = this;
                return true;
        }
}

bool Sphere::intersect (const Ray& ray, float& depth, float rayMin, float rayMax)
{
        lastTestedRayId = ray.id;
        lastTestedRayResult.isIntersect = false;
        Vector diff = (ray.origin - centre);
        float b = 2.0f * (ray.dir * diff);
        float c = diff * diff - radius * radius;

        float discriminant = b * b - 4.0f * c;
        if(discriminant < 0.0f)
                return false;
        else
        {
                depth = (-b - sqrtf(discriminant)) * 0.5f;
                lastTestedRayResult.isIntersect = true;
                lastTestedRayResult.depth               = depth;
                lastTestedRayResult.material    = this->material;
                if(ray.isShadowRay) return true;
                lastTestedRayResult.point = ray.origin + ray.dir * depth;
                lastTestedRayResult.normal.setDifference(lastTestedRayResult.point, centre);
                lastTestedRayResult.normal *= 1.0f / radius;
                lastTestedRayResult.object = this;
                return true;
        }
}