# Tangent plane for point on surface mesh

I am working on the generation of hexahedral mesh , for surface construction i need to find the tangent plane for each point on the surface.

• The tangent plane depends on your surface interpolation method. Do you know what method you are using? Jan 29, 2013 at 17:27
• "Please help me with the code" is the wrong question. Here you'll get the concepts and understanding, the code is your job. Jan 29, 2013 at 19:16
• Please rephrase your question to tell us the concepts you're unclear about. Jan 29, 2013 at 21:44

## 2 Answers

If you use OpenGL, you will have to split your hexahedrons into triangles. Each point lies inside a triangle, so find the tangent plane for that triangle.

• Thank you for your response. I am actually looking for a way to find the tangent plane. Could you be able exaplain me the process
– AJAY
Jan 29, 2013 at 15:31
• I think you don't understand what tangent plane is. Do you? Jan 29, 2013 at 21:25
• Hello Ivan, Thank you for your advice. Well, the problem is I have surface some of the elements are triangles and some of them are quadrilaterals. I know that i can split the quadrilaterals in to triangles use the same formula as triangles. But, is there any method calculate the tangent plane for quadrilaterals.
– AJAY
Jan 30, 2013 at 8:42

(continued from Ivan's answer)

What format do you want the tangent plane in? A combination of (point, normal) already is a unique representation of a tangent plane. For example, if I have a triangle at points A, B, C; I can find the normal via the cross product N = (A-B)x(A-C).

Since (A, N) uniquely defines the plane, I could write it out as the equation

Nx(x - Ax) + Ny(y - Ay) + Nz(z - Az) = 0

• Hello Jimmy, Thank you for your advice. Well, the problem is I have surface some of the elements are triangles and some of them are quadrilaterals. I know that i can split the quadrilaterals in to triangles use the same formula as triangles. But, is there any method calculate the tangent plane for quadrilaterals.
– AJAY
Jan 30, 2013 at 8:42