Before going into specifics, I'm mostly interested in making simple 2D games with some 3D elements, not fancy AAA.
Based on what I've gathered, everyone seems to suggest to use OpenGL 3+ with shaders, instead of the 2.x style of
glVertex/glBegin/glEnd. Now I do understand the reasoning behind moving to VBO and shaders, as it gives greater control and performance.
But it seems that it also forces me to produce all of the geometry beforehand, buffer is it somehow, generate the VBO, and then send all that to a single vertex/fragment shader to render it, correct?
It also seems that I need to have a single shader process completely different types of vertices, which means there has to be a lot of redundant information in the VBO? Or is there a way to have multiple VBOs? I know it is possible to have multiple shaders and swap them, but I haven't figured out when one would need that, considering I only have a single active VBO?
Now comes the real question.
Consider I'm making something like a procedurally generated growing plant, where each frame changes the whole geometry slightly (or just adds something). For simplicity, let's just say the plant is a bunch of colored ellipses. How do I structure the algorithm for "drawing" the plant? Would I just build the whole VBO from scratch, given that the vertex data changes all the time?
Also considering that the number of plants and their size can vary greatly, how do I avoid re-allocate memory for the VBO on each frame? Do I just use a large enough buffer, which would be able to store the maximum amount of geometry I can manage in my shaders (like a 512MB static array)?