Using OpenGL vertex buffers in C++.

Question

I've loaded a Wavefront .obj file and drawn it in immediate mode, and it works fine.
I'm now trying to draw the same model with a vertex buffer, but I have a question.

My model data is organized in the following structures:

struct Vert
{
 double x;
 double y;
 double z;
};

struct Norm
{
 double x;
 double y;
 double z;
};

struct Texcoord
{
 double u;
 double v;
 double w;
};

struct Face
{
 unsigned int v[3];
 unsigned int n[3];
 unsigned int t[3];
};

struct Model
{
 unsigned int vertNumber;
 unsigned int normNumber;
 unsigned int texcoordNumber;
 unsigned int faceNumber;

 Vert * vertArray;
 Norm * normArray;
 Texcoord * texcoordArray;
 Face * faceArray;
};

As it is now, I don't think there is any redundant data, since multiple face structures can point to the same vertex, normal, or texture coordinate.

When I make vbo's for the vertex positions, normals, and texture coordinates, and assign data to them with glBufferData, do I have to have make arrays with redundant data so that they will all have the same number of elements in the same order? I'd like to know if there is a simpler way to fill the buffers with the way I already have the model's data organized.

Answer 1

Yes, you have to duplicate vertices since GL only supports one index array for all vertex attributes.

On the other hand, don't use doubles, just use floats, most GPUs don't support them and will convert them to floats.