Understanding cross product without delving too much on Linear algebra

skadush · 2016-01-17T05:45:07

In this tutorial on Exploding Objects topics. The author talks about getting the normal vector using two vectors parallel to the surface of triangle. I just have few questions regarding this. Though I know I am not that good at math. I believe understanding this or just a little on how it works will help me a lot when dealing with 3D. First of the author said something like this If we were to retrieve two vectors a and b that are parallel to the surface of the triangle we can retrieve the normal vector by doing a cross product on those vectors But then what is a surface? Googling it, I think it is just the whole area of a triangle. But then he said "parallel" to the surface. that means this surface has a direction? If I understand parallel vectors. it is a vector that have the same direction. So if we are talking about 2D triangle, at what direction does the surface of the triangle is pointing to? Is this a correct visualization Second is about plane The author said something like this Subtracting two vectors from each other results in a vector that is the difference of the two vectors and since all 3 points lie on the triangle plane, subtracting any of its vectors from each other results in a vector parallel to the plane. If I am right plane is is about flat shapes. I also going to ask this. if it is flat shape, where is it pointing to? Is the plane and surface the same here? thanks