Question

What is the best way to store dynamic data for use in VBO (or vertex arrays). Only examples I saw were 2D static arrays and the pointer to that array was used with next parameters as stride, bytes used for one element etc. I can use “dynamic” arrays so I can specify it’s size on-air, but just once. My point is that if you, for example, already drawing 1000 points (talking about 2D so I think point is better then vertex) as line strip and you add new point, this way you have to make new array with size of 1001, copy everything from old to new field, add new point and send it down to graphic’s memory. Best way is to use vectors or deques as temporary storage, but then I have to convert to array and again send it down.

So is there better way to do this? Can I only add new part to VBO without sending down the old data? Or better way to store data/using vector as data source without conversion?

Answer 1

I usually just use the ‘ole vector trick:

struct GL_Vertex
{
    Eigen::Vector2f tex;
    Eigen::Vector3f color;
    Eigen::Vector3f pos;
};
...
vector<GL_Vertex> buf(1000);
...
glTexCoordPointer( 2, GL_FLOAT, sizeof(GL_Vertex), &buf[0].tex );
glColorPointer( 3, GL_FLOAT, sizeof(GL_Vertex), &buf[0].color );
glVertexPointer( 3, GL_FLOAT, sizeof(GL_Vertex), &buf[0].pos );