deargui-vpl/ref/virtools/Samples/Behaviors/ParticlesSystem/behaviors src/ParticleTools.cpp

#include "CKAll.h"

#include "ParticleTools.h"

BOOL 
RayBoxIntersection(const VxBbox &box, VxVector& p0,VxVector &p1,VxVector &res,VxVector &norm)
{
	BOOL inside = TRUE;
	int quadrant[3];
	int i;
	int whichPlane;
	VxVector maxT;
	VxVector candidatePlane;
	// Find candidate planes; this loop can be avoided if
   	//rays cast all from the eye(assume perpsective view) 
	for (i=0; i<3; i++)
		if(p0.v[i] < box.Min.v[i])
		{
			quadrant[i] = 1;
			candidatePlane.v[i] = box.Min.v[i];
			norm.v[i]=-1.0f;
			inside = FALSE;
		}
		else 
		if (p0.v[i] > box.Max.v[i])
		{
			quadrant[i] = 0;
			candidatePlane.v[i] = box.Max.v[i];
			norm.v[i]=1.0f;
			inside = FALSE;
		}
		else
		{
			norm.v[i] = 0.0f;
			candidatePlane.v[i] = 0.0f;
			quadrant[i] = 2;
		}

	// Ray p0.v inside bounding box 
	if(inside)
	{
		res = p0;
		return -1;
	}

	VxVector dir=p1-p0;

	// Calculate T distances to candidate planes 
	for (i = 0; i < 3; i++)
		if (quadrant[i] != 2 && dir[i] !=0.)
			maxT.v[i] = (candidatePlane.v[i]-p0.v[i]) / dir[i];
		else
			maxT.v[i] = -1.;

	// Get largest of the maxT.v's for final choice of intersection 
	whichPlane = 0;
	for (i = 1; i < 3; i++)
		if (maxT.v[whichPlane] < maxT.v[i])
			whichPlane = i;


	// Check final candidate actually inside box 
	if (maxT.v[whichPlane] < 0.) return (FALSE);
	if (maxT.v[whichPlane] > 1.) return (FALSE);
	for (i = 0; i < 3; i++)
		if (whichPlane != i)
		{
			norm.v[i]=0.0f;
			res.v[i] = p0.v[i] + maxT.v[whichPlane] *dir[i];
			if (res.v[i] < box.Min.v[i] || res.v[i] > box.Max.v[i])
				return (FALSE);
		} else {
			res.v[i] = candidatePlane.v[i];
		}
	return 1;	
}	

BOOL 
RayInteriorBoxIntersection(const VxBbox &box, VxVector& p0,VxVector &p1,VxVector &res,VxVector &norm)
{
	BOOL inside = TRUE;
	int quadrant[3];
	int i;
	int whichPlane;
	VxVector maxT;
	VxVector candidatePlane;
	// Find candidate planes; this loop can be avoided if
   	//rays cast all from the eye(assume perpsective view) 
	for (i=0; i<3; i++)
		if(p0.v[i] < box.Min.v[i])
		{
			quadrant[i] = 1;
			candidatePlane.v[i] = box.Min.v[i];
			norm.v[i]=-1.0f;
			inside = FALSE;
		}
		else 
		if (p0.v[i] > box.Max.v[i])
		{
			quadrant[i] = 0;
			candidatePlane.v[i] = box.Max.v[i];
			norm.v[i]=1.0f;
			inside = FALSE;
		}
		else
		{
			norm.v[i] = 0.0f;
			candidatePlane.v[i] = 0.0f;
			quadrant[i] = 2;
		}

	// Ray p0.v inside bounding box 
	if(inside)
	{
		res = p0;
		return TRUE;
	}

	VxVector dir=p1-p0;

	// Calculate T distances to candidate planes 
	for (i = 0; i < 3; i++)
		if (quadrant[i] != 2 && dir[i] !=0.)
			maxT.v[i] = (candidatePlane.v[i]-p0.v[i]) / dir[i];
		else
			maxT.v[i] = -1.;

	// Get largest of the maxT.v's for final choice of intersection 
	whichPlane = 0;
	for (i = 1; i < 3; i++)
		if (maxT.v[whichPlane] < maxT.v[i])
			whichPlane = i;


	// Check final candidate actually inside box 
	if (maxT.v[whichPlane] < 0.) return (FALSE);
	if (maxT.v[whichPlane] > 1.) return (FALSE);
	for (i = 0; i < 3; i++)
		if (whichPlane != i)
		{
			norm.v[i]=0.0f;
			res.v[i] = p0.v[i] + maxT.v[whichPlane] *dir[i];
			if (res.v[i] < box.Min.v[i] || res.v[i] > box.Max.v[i])
				return (FALSE);
		} else {
			res.v[i] = candidatePlane.v[i];
		}
	return (TRUE);	
}	

BOOL 
RaySphereIntersection(VxVector& p0,VxVector &p1,VxVector &res,VxVector &norm)
{
	float dist0 = SquareMagnitude(p0);
	float dist1 = SquareMagnitude(p1);
	if(((dist0 < 1) && (dist1 > 1)) || ((dist0 > 1) && dist1 < 1)) { // in the tube limits radius
		VxVector V = Normalize(p1-p0);
		float v;
		if(dist0<1) {
			v = DotProduct(p0,V);
		} else {
			v = DotProduct(-p0,V);
		}
		float disc = 1 - (DotProduct(p0,p0)-v*v);
		res = p0+(v-sqrtf(disc))*V;
		norm = res;
		return TRUE;
	}
	return FALSE;
}

BOOL 
RayTubeIntersection(VxVector& p0,VxVector &p1,VxVector &res,VxVector &norm)
{
	VxVector O(0,0,0);
	VxVector d(0,0,1);
	VxRay ray(O,d,NULL);
	float dist0 = ray.SquareDistance(p0);
	float dist1 = ray.SquareDistance(p1);
	if(((dist0 < 1) && (dist1 > 1)) || ((dist0 > 1) && dist1 < 1)) { // in the tube limits radius
		if(((p1.z < 1) || (p0.z < 1))&&((p1.z > -1) || (p0.z > -1))) { // in the tube height limit
			float a,b,c,delta,t;
			VxVector ray = p1 - p0;
			
			// the tube itself
			a = ray.v[0]*ray.v[0]+ray.v[1]*ray.v[1];
			b = 2*(p0.v[0]*p0.v[0]+p0.v[1]*p0.v[1]);
			c = p0.v[0]*p0.v[0]+p0.v[1]*p0.v[1] - 2;
			
			delta = b*b-4*a*c; 	 
			
			if(delta>=0) {
				delta=(float)sqrt(delta);
				t = (-b-delta)/(2*a);
				if(t<0) {
					t = (-b+delta)/(2*a) ;
					if(t<0) {
						return FALSE;
					}
				}
			}

			res = p0+t*ray;
			norm = res;
			norm.z = 0;
			return TRUE;
		}
	}
	return FALSE;
}

BOOL 
RayPlaneIntersection(VxVector& Normal,VxVector& pt,VxVector &ori,VxVector &dest,VxVector &res)
{
	VxVector V=dest-ori;
	VxVector AP=ori-pt;
	
	float denom=DotProduct(V,Normal);
	if (denom==0.0f) return FALSE;
	float t=-DotProduct(Normal,AP)/denom;
	if (t<0) return FALSE;
	if (t>1) return FALSE;
	res = ori+t*V;
	
	return TRUE;
}