kernel.cg

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const float PI = 3.1415926535;
/*
float kernel(float r_sq, float h)
{
	return 1/(PI*h*h*h)*exp(-r_sq/h/h);
}
*/

float spiky_kernel(float len, float h, float m)
{
	const float PI = 3.1415926535f;
	float h_r;
	float result;
	
	//len *= 0.5f;
	h_r = h - len;

	if (h_r > 0.0f)
		result = 0.5*m*15.0f/(PI*h*h*h*h*h*h)*pow(h_r, 3);//*h_r*h_r;
//		result = 0.5*m*15.0f/(PI*h*h*h*h*h*h)*h_r*h_r*h_r;
	else result = 0.0f;
	//if (len > h)
		//result = 0.0f;

	return result;
}

float3 grad_kernel(float r, float h, float3 p0, float3 p1, float m)
{
	return spiky_kernel(r, h, m)*(p0 - p1);
	/*
	r *= 2.0f;

	float inv_h = 1.0f/h;
	float ck = -1.0f*inv_h*inv_h;
//	float k = 1/(PI*h*h*h)*exp(-r_sq/h/h);
	float k = 1.0*inv_h*inv_h*inv_h/PI*exp(-r*r*inv_h*inv_h);

	return ck*k*(p0 - p1);
	*/
}

/*
float3 inverse_kernel(vector3* grad, float r, float h, const vector3* p0, const vector3* p1)
{
	const float PI = 3.1415926535f;

	float inv_h;
	float ck;
	float k;

	r *= 2.0f;

	inv_h = 1.0f/h;
	ck = -1.0f*inv_h*inv_h;
	k = 1.0*inv_h*inv_h*inv_h/PI*exp(-r*r*inv_h*inv_h);

	vec3_sub(grad, p0, p1);
	vec3_scale(grad, ck*k);
}
*/
float spline_kernel(float r, float h)
{
	float q;
	float result;
	float _2_q;

	q = r/h;

	if (q < 1)
	{
		result = 1 + q*q*(-3.0f/2.0f + 3.0f/4.0f*q);
	}
	else if (q < 2)
	{
		_2_q = 2.0f - q;
		result = 1.0f/4.0f*_2_q*_2_q*_2_q;
	}
	else 
	{
		result = 0.0f;
	}

	return (1/(PI*h*h*h))*result;
}

float poly6_kernel(float lensq, float h, float m)
{
	float k;
	float h2_r2;

	h2_r2 = h*h -lensq;

	//return max(315.0f/(64.0f*PI*pow(h, 9))*h2_r2*h2_r2*h2_r2, 0.0f);
	
	if (h2_r2 > 0.0f)
		k = m*315.0f/(64.0f*PI*h*h*h*h*h*h*h*h*h)*pow(h2_r2, 3);
//		k = 315.0f/(64.0f*PI*h*h*h*h*h*h*h*h*h)*h2_r2*h2_r2*h2_r2;
//		k = 315.0f/(64.0f*PI*pow(h, 9))*h2_r2*h2_r2*h2_r2;
	else k = 0.0f;

	return k;
	/*
		return 0.0;

	return 315.0f/(64.0f*PI*pow(h, 9))*h2_r2*h2_r2*h2_r2;*/
}

float lap_viscosity_kernel(float r, float h, float m, float mu)
{
//	return max(45.0*(h - r)/(PI*h*h*h*h*h*h), 0.0f);

	float k;

	if (h > r)
		k = mu*m*45.0*(h - r)/(PI*h*h*h*h*h*h);
	else k = 0.0f;

	return k;
	
	//return 45.0*(h - r)/(PI*h*h*h*h*h*h);
}

/*
void main(float2 index_coord : TEXCOORD0,
		  uniform samplerRECT pos_rect   : TEXUNIT0,
		  uniform samplerRECT index_rect : TEXUNIT1,
		  out float4 result : COLOR)
{
	const float h = 0.005f;

	float3 pos0 = f3texRECT(pos_rect, float2(index_coord.y, 0));//pos_coord);
	float3 pos1 = f3texRECT(pos_rect, float2(f1texRECT(index_rect, index_coord), 0));

	float3 diff = pos0 - pos1;
	float distsq = dot(diff, diff);
	float k = kernelsq(distsq, h);
	//float k = spline_kernel(length(diff), h);
	float k = kernel(dot(diff, diff), h);

	result.xyz = -2.0/h/h*diff*k;
	result.w = k;
	
	
	//result.x = pos_coord.x;
	//result.x = f1texRECT(index_rect, index_coord);
	
}
*/