Function SampleSDFGrad

extensions/flexExtRigid.cpp:49–65

return normal of signed distance field

// return normal of signed distance field
Vec3 SampleSDFGrad(const float* sdf, int dim, int x, int y, int z)
{
	int x0 = std::max(x-1, 0);
	int x1 = std::min(x+1, dim-1);

	int y0 = std::max(y-1, 0);
	int y1 = std::min(y+1, dim-1);

	int z0 = std::max(z-1, 0);
	int z1 = std::min(z+1, dim-1);

	float dx = (SampleSDF(sdf, dim, x1, y, z) - SampleSDF(sdf, dim, x0, y, z))*(dim*0.5f);
	float dy = (SampleSDF(sdf, dim, x, y1, z) - SampleSDF(sdf, dim, x, y0, z))*(dim*0.5f);
	float dz = (SampleSDF(sdf, dim, x, y, z1) - SampleSDF(sdf, dim, x, y, z0))*(dim*0.5f);

	return Vec3(dx, dy, dz);
}

} // anonymous namespace