// Seed random number generator		
void BerconGradient::seedRandomGen(ShadeContext& sc) {
	int seed = 1;
	if (previewMatIDMode) {
		seed = sc.mtlNum;
	} else {
		if (p_randMat) { 		
			seed += sc.mtlNum;
		}
		if (p_randObj) {
			int hand = (int)sc.Node()->GetHandle();
			seed += hand*(hand*hand*15731 + 789221);
		}
		if (p_randPar) {
			Object *ob = sc.GetEvalObject();		
			if (ob && ob->IsParticleSystem()) {
				ParticleObject *obj = (ParticleObject*)ob;
				IChkMtlAPI* chkMtlAPI = static_cast<IChkMtlAPI*>(obj->GetInterface(I_NEWMTLINTERFACE));
				if ((chkMtlAPI && chkMtlAPI->SupportsParticleIDbyFace())) {
					int id = chkMtlAPI->GetParticleFromFace(sc.FaceNumber());
					seed += id*(id*id*571 + 789221);
				}			
			}
		}
		if (p_randTile) {
			seed += (int)(sc.UVW(99).z);
		}
	}

	seed *= p_seed;
	srand(seed*(seed*seed*15731 + 789221));	
}
// Calculates 0..1 value which is given to the gradient
float BerconGradient::getGradientValue(ShadeContext& sc) {
	switch (p_type) {
		case 0: { // UVW
			break; // Handled in main evaluation
		}
		case 1: { // Normal
			switch (p_normalFunction) {
				case 0: { // Perpendicular / Parallel
					return fabs(getGradientValueNormal(sc));
				}
				case 1: { // Towards / Away
					return (getGradientValueNormal(sc) + 1.f) / 2.f;	
				}
				case 2: { // Fresnel
					// NOTE: Should this get IOR from sc.GetIOR()?
					//		 I think not since its just a map, not material.
					//		 You get more predictable behaviour with constant 1.f.
					static float n1 = 1.0f;								
					float cti = fabs(getGradientValueNormal(sc));					
					float stt = (n1 / p_ior) * sqrt(1 - cti * cti);
					float ctt = sqrt(1 - stt * stt);
					float rs = (p_ior * ctt - n1 * cti ) / (p_ior * ctt + n1 * cti);
					rs = rs * rs;
					float rp = (n1 * ctt - p_ior * cti ) / (n1 * ctt + p_ior * cti);
					rp = rp * rp;
					return 1.f - 0.5f * (rs + rp);				
				}
			}
		}
		case 2: { // Distance
			return getGradientValueDist(sc);		
		}
		case 3: { // Light
			return Intens(sc.DiffuseIllum());
		}
		case 4: { // Map			
			return p_maptex?p_maptex->EvalMono(sc):0.f; // TODO: Evaluate submaps color, bump is tougher DELTA shift with BerconSC?
		}
		case 5: { // Random
			seedRandomGen(sc);
			return (float)sfrand();		
			break;
		}
		case 6: { // Particle age
			Object *ob = sc.GetEvalObject();		
			if (ob && ob->IsParticleSystem()) {				
				ParticleObject *obj = (ParticleObject*)ob;
				TimeValue t = sc.CurTime();
				TimeValue age  = obj->ParticleAge(t,sc.mtlNum);
				TimeValue life = obj->ParticleLife(t,sc.mtlNum);
				if (age>=0 && life>=0) 
					return float(age)/float(life);
			}
			break;
		}
		case 7: { // Particle speed
			Object *ob = sc.GetEvalObject();		
			if (ob && ob->IsParticleSystem()) {
				ParticleObject *obj = (ParticleObject*)ob; 
				/*IChkMtlAPI* chkMtlAPI = static_cast<IChkMtlAPI*>(obj->GetInterface(I_NEWMTLINTERFACE));
				if ((chkMtlAPI&&chkMtlAPI->SupportsParticleIDbyFace()))
					return (Length(obj->ParticleVelocity(sc.CurTime(),chkMtlAPI->GetParticleFromFace(sc.FaceNumber()))) - p_rangeMin) / (p_rangeMax - p_rangeMin);
				else*/
					return Length(obj->ParticleVelocity(sc.CurTime(),sc.mtlNum));
			}									
			break;
		}
		case 8: { // Particle size
			Object *ob = sc.GetEvalObject();		
			if (ob && ob->IsParticleSystem()) {
				ParticleObject *obj = (ParticleObject*)ob;
				return obj->ParticleSize(sc.CurTime(),sc.mtlNum);
			}									
			break;
		}
		default:
			break;
	}
	return 0.f;
}