// Description: Convenience function for setting distance attenuation.
//
// Arguments: light HW light ID.
// ref_dist Reference distance.
// ref_br Reference brightness.
// dist_func Attenuation characteristics.
public Vector3 GetLightDistAttn(int frame)
{
float k0, k1, k2;
float ref_dist = _refDist.GetFrameValue(frame);
float ref_br = _refBright.GetFrameValue(frame);
DistAttnFn dist_func = DistanceFunction;
if (ref_dist < 0.0F || ref_br <= 0.0F || ref_br >= 1.0F)
{
dist_func = DistAttnFn.Off;
}
switch (dist_func)
{
case DistAttnFn.Gentle:
k0 = 1.0F;
k1 = (1.0F - ref_br) / (ref_br * ref_dist);
k2 = 0.0F;
break;
case DistAttnFn.Medium:
k0 = 1.0F;
k1 = 0.5F * (1.0f - ref_br) / (ref_br * ref_dist);
k2 = 0.5F * (1.0f - ref_br) / (ref_br * ref_dist * ref_dist);
break;
case DistAttnFn.Steep:
k0 = 1.0F;
k1 = 0.0F;
k2 = (1.0F - ref_br) / (ref_br * ref_dist * ref_dist);
break;
case DistAttnFn.Off:
default:
k0 = 1.0F;
k1 = 0.0F;
k2 = 0.0F;
break;
}
return(new Vector3(k0, k1, k2));
}
public static Vector3 GetLightDistCoefs(float distance, float brightness, DistAttnFn distFunc)
{
//constant attn, linear attn, quadratic attn
//k2x^2 + k1x + k0
float k0, k1, k2;
if (distance < 0.0F || brightness <= 0.0F || brightness >= 1.0F)
{
distFunc = DistAttnFn.Off;
}
switch (distFunc)
{
case DistAttnFn.Gentle:
k0 = 1.0f;
k1 = (1.0f - brightness) / (brightness * distance);
k2 = 0.0f;
break;
case DistAttnFn.Medium:
k0 = 1.0f;
k1 = 0.5f * (1.0f - brightness) / (brightness * distance);
k2 = 0.5f * (1.0f - brightness) / (brightness * distance * distance);
break;
case DistAttnFn.Steep:
k0 = 1.0f;
k1 = 0.0f;
k2 = (1.0f - brightness) / (brightness * distance * distance);
break;
case DistAttnFn.Off:
default:
k0 = 1.0f;
k1 = 0.0f;
k2 = 0.0f;
break;
}
return(new Vector3(k0, k1, k2));
}
