geometry.cpp

/*
 * pbrt source code Copyright(c) 1998-2004 Matt Pharr and Greg Humphreys
 *
 * All Rights Reserved.
 * For educational use only; commercial use expressly forbidden.
 * NO WARRANTY, express or implied, for this software.
 * (See file License.txt for complete license)
 */

// geometry.cpp*
#include "geometry.h"
// BBox Method Definitions
BBox Union(const BBox &b, const Point &p) {
	BBox ret = b;
	ret.pMin.x = min(b.pMin.x, p.x);
	ret.pMin.y = min(b.pMin.y, p.y);
	ret.pMin.z = min(b.pMin.z, p.z);
	ret.pMax.x = max(b.pMax.x, p.x);
	ret.pMax.y = max(b.pMax.y, p.y);
	ret.pMax.z = max(b.pMax.z, p.z);
	return ret;
}
BBox Union(const BBox &b, const BBox &b2) {
	BBox ret;
	ret.pMin.x = min(b.pMin.x, b2.pMin.x);
	ret.pMin.y = min(b.pMin.y, b2.pMin.y);
	ret.pMin.z = min(b.pMin.z, b2.pMin.z);
	ret.pMax.x = max(b.pMax.x, b2.pMax.x);
	ret.pMax.y = max(b.pMax.y, b2.pMax.y);
	ret.pMax.z = max(b.pMax.z, b2.pMax.z);
	return ret;
}
void BBox::BoundingSphere(Point *c, float *rad) const {
	*c = .5f * pMin + .5f * pMax;
	*rad = Distance(*c, pMax);
}
bool BBox::IntersectP(const Ray &ray, float *hitt0,
		float *hitt1) const {
	float t0 = ray.mint, t1 = ray.maxt;
	for (int i = 0; i < 3; ++i) {
		// Update interval for _i_th bounding box slab
		float invRayDir = 1.f / ray.d[i];
		float tNear = (pMin[i] - ray.o[i]) * invRayDir;
		float tFar  = (pMax[i] - ray.o[i]) * invRayDir;
		// Update parametric interval from slab intersection $t$s
		if (tNear > tFar) swap(tNear, tFar);
		t0 = tNear > t0 ? tNear : t0;
		t1 = tFar  < t1 ? tFar  : t1;
		if (t0 > t1) return false;
	}
	if (hitt0) *hitt0 = t0;
	if (hitt1) *hitt1 = t1;
	return true;
}