Re: RayShade and spot light bug fix.

[Roger H. <rog...@mi...>]

Hi,

To fix the problem with spot lights:


In LibLight/spot.h

replace the lines:


#define LightSpotCreate(c,f,t,p,i,o) LightCreate( \
			(LightRef)SpotCreate(f,t,p,i,o), SpotMethods(), c)
typedef struct {
	Vector pos, dir;
	Float coef, radius, falloff;
} Spotlight;

extern Spotlight *
SpotCreate(Vector *from,Vector *to,Float coef,Float in,Float out);


with:

#define LightSpotCreate(c,f,t,i,o,at,fo) LightCreate( \
			(LightRef)SpotCreate(f,t,i,o,at,fo), SpotMethods(), c)
typedef struct {
	Vector pos, dir;
	Float hotAngle ;
	Float outerAngle ;
	Float cosHotAngle ;
	Float cosOuterAngle ;
	int	attenuation ;
	int	fallOff ;
} Spotlight;

extern Spotlight *
SpotCreate ( Vector* from , Vector* dir , Float hotAngle , Float  
outerAngle , int attenuation , int fallOff ) ;



Then in LibLight/spot.cpp replace:


static Float rampup(Float left,Float right,Float at);

static Float SpotAtten(Spotlight *lp, Vector *dir);
Spotlight *
SpotCreate(
         Vector          *from,
         Vector          *to,
         Float           coef,
         Float           in,
         Float           out)
{
	Spotlight *spot;

	spot = (Spotlight *)share_malloc(sizeof(Spotlight));
	spot->pos = *from;
	VecSub(*to, *from, &spot->dir);
	if (VecNormalize(&spot->dir) == 0. || in > out) {
		RLerror(RL_ABORT,"Invalid spotlight specification.\n");
		return (Spotlight *)NULL;
	}
	spot->coef = coef;
	spot->radius = cos(deg2rad(in));
	spot->falloff = cos(deg2rad(out));

	return spot;
}




with:




static Float SpotAtten(Spotlight *lp, Vector *dir);
Spotlight *
SpotCreate(
         Vector          *from,
         Vector          *dir,
         Float           hotAngle,
         Float           outerAngle ,
		int				attenuation ,
		int				fallOff )
{
	Spotlight *spot;

	spot = (Spotlight *)share_malloc(sizeof(Spotlight));
	spot->pos = *from;
	spot->dir.x = dir->x ;
	spot->dir.y = dir->y ;
	spot->dir.z = dir->z ;
	if (VecNormalize(&spot->dir) == 0. || hotAngle > outerAngle ) {
		RLerror(RL_ABORT,"Invalid spotlight specification.\n");
		return (Spotlight *)NULL;
	}
	spot->hotAngle = hotAngle ;
	spot->outerAngle = outerAngle ;
	spot->cosHotAngle = cos ( hotAngle ) ;
	spot->cosOuterAngle = cos ( outerAngle ) ;
	spot->attenuation = attenuation ;
	spot->fallOff = fallOff ;

	return spot;
}




and further down the same file replace:



/*
  * Compute intensity of spotlight along 'dir'.
  */
static Float
SpotAtten(
         Spotlight       *lp,
         Vector          *dir)
{
	Float costheta, atten;

	costheta = -dotp(dir, &lp->dir);
	/*
	 * Behind spotlight.
	 */
	if (costheta <= 0.)
		return 0.;
	/*
	 * Intensity is the product of costheta raised to lp->coef and
	 * a function that smoothly interpolates from 0 at
	 * costheta=lp->falloff to 1 at costheta=lp->radius.
	 */
	atten = pow(costheta, lp->coef);
	if (lp->radius > 0.)
		atten *= rampup(lp->falloff, lp->radius, costheta);
	return atten;
}

/*
  * Cubic interpolation between 0 at left and 1 at right, sampled at  
'at'
  * It is assumed that right >= left.
  */
Float
rampup(Float left,Float right,Float at)
{
	if (at < left)
		return 0.;
	else if (at > right)
		return 1.;

	if (right == left)
		return 0.;

	at = (at - left) / (right - left);
	return (3 - 2*at)*at*at;
}



with:



#define kQ3PiOver2                              ((Float)  
(3.1415926535898 / 2.0))
static const float eMinus1 = exp ( 1.0f ) - 1.0f ;

/*
  * Compute intensity of spotlight along 'dir'.
  */
static Float
SpotAtten(
         Spotlight       *lp,
         Vector          *dir)
{
	Float costheta, atten;

	costheta = -dotp(dir, &lp->dir);
	/*
	 * Behind spotlight.
	 */
	if (costheta <= 0.)
		return 0.;

	if ( costheta < lp->cosOuterAngle )
		return 0.0 ;

	atten = costheta ;
	if (lp->cosHotAngle > 0.) // What is this all about ?
		{
		Float fallOffMultiplier = 1.0 ;
		if ( lp->fallOff == 1 /*kQ3FallOffTypeLinear*/ )
			{
			if ( costheta < lp->cosHotAngle )
				{
				Float angle = acos ( costheta ) ;
				fallOffMultiplier = ( lp->outerAngle - angle ) / ( lp->outerAngle  
- lp->hotAngle ) ;
				}
			}
		else
		if ( lp->fallOff == 2/*kQ3FallOffTypeExponential*/ )
			{
			if ( costheta < lp->cosHotAngle )
				{
				Float angle = acos ( costheta ) ;
				fallOffMultiplier = ( exp ( ( lp->outerAngle - angle ) / ( lp- 
 >outerAngle - lp->hotAngle ) ) - 1 ) / eMinus1 ;
				}
			}
		else
		if ( lp->fallOff == 3/*kQ3FallOffTypeCosine*/ )
			{
			if ( costheta < lp->cosHotAngle )
				{
				Float angle = acos ( costheta ) ;
				fallOffMultiplier = cos ( ( angle - lp->hotAngle ) * kQ3PiOver2 /  
( lp->outerAngle - lp->hotAngle ) ) ;
				}
			}

				
/*
		This may be required some time but presently neither the attenuation  
nor the world pixel position are available. Maybe it should go  
somewhere else in the calculations
		if ( lp->attenuation != kQ3AttenuationTypeNone )
			{
			switch ( lp->attenuation )
				{
	    		case kQ3AttenuationTypeInverseDistance :
	    			{
	    			fallOffMultiplier *= 1.0f / Distance ( pixelWorldPos - lp- 
 >pos ) ;
	    			break ;
	   				}
				case kQ3AttenuationTypeInverseDistanceSquared :
	    			{
	    			fallOffMultiplier *= 1.0f / DistanceSquared ( pixelWorldPos -  
lp->pos ) ;
	    			break ;
	   				}
				}
			}
*/		
		
		atten *= fallOffMultiplier ;
		}
	return atten;
}





Nearly there. In RT_Light.cpp, in subroutine RT_AddSpotLight  replace:


     theVector.x = -inDirection->x;
     theVector.y = -inDirection->y;
     theVector.z = -inDirection->z;

     switch(inFallOffType)
     {
         case kQ3FallOffTypeNone:
             theCoeff = 0.0f;
             break;
         case kQ3FallOffTypeLinear:
             theCoeff = 1.0f;
             break;
         case kQ3FallOffTypeExponential:
             theCoeff = 0.8f;
             break;
         case kQ3FallOffTypeCosine:
             theCoeff = 2.0f;
             break;
     }
     theLight = LightSpotCreate(&theColor,
                   &thePos,
                   &theVector,
                   theCoeff,
                   Q3Math_RadiansToDegrees(hotAngle),
                   Q3Math_RadiansToDegrees(outerAngle));



with:


     theVector.x = inDirection->x;
     theVector.y = inDirection->y;
     theVector.z = inDirection->z;

     theLight = LightSpotCreate(&theColor,
                   &thePos,
                   &theVector,
                   hotAngle ,
                   outerAngle ,
				  kQ3AttenuationTypeNone ,
				  inFallOffType ) ; // Use kQ3AttenuationTypeNone until we find we  
need thee proper value



Thats it.

I tried including the file which defines kQ3FallOffTypeExponential etc  
but had problems with multiply defined names, hence the slightly  
questionable way I've used constants 1,2 and 3 in SpotAtten.

Roger.