Someone

void Mat4MulVec3Project(float mat[][4], float *vec)
{
	float w;

	w = vec[0]*mat[0][3] + vec[1]*mat[1][3] + vec[2]*mat[2][3] + mat[3][3];
	Mat4MulVecfl(mat, vec);

	vec[0] /= w;
	vec[1] /= w;
	vec[2] /= w;
}