how to follow the terrain height

hi everyone,

i would be appreciate if anyone could help me out, on how to follow the terrain height?

i have a .wrl file, and have converted it in 3DExploration to get the coordinates, and it works. so now i have the terrain verticies, normals, face_indicies and texture coordinates.

my problem is:

how to get/detect the current viewer coordinates(position), so when up arrow key is being pressed, the 'viewer' will follow the terrain height?

pleaseee... please help me out, any coding sample to refer?

thanks in advance.

[dans]

Solve the plane equation for the point that you're standing on.

The plane equation is (x)nx + (y)ny + (z)nz + c = 0.

{nx, ny, nz} is the plane normal of the current cell.

c is a constant offset which can be solved by plugging in
the coordinates of one of the corner points of the cell.

Your current position on the map is {x,z} solve for y.

In pseudocode:

// Get my current position on the map
pos = {something};

// Figure out the current cell I'm standing in
cell = FindCell(pos);

// Get the plane normal of the cell or triangle
normal = cell.normal;

// Get one of the corner points of the cell
point = cell.point(1);

// Solve for c, the plane equation offset
c = normal.x * point.x + normal.y * point.y + normal.z * point.z;

// Now solve for the y component of my position
pos.y = (c - normal.x * pos.x - normal.z * pos.z) / normal.y;