OpenGL VBO storage and templates

Question

I have a question about VBO's. Let's say just as an example I'm trying to build a voxel style engine that makes even a 16x16x16 chunk.

Do I store the map information in the VBO? How do I get the verticies for a cube? The way I'm thinking about it, the VBO would require 24 vector3 variables (vectors for each cube at each location). That seems like a lot.

is there some way to have a single 'cube' VBO template, then somehow change the coordinates for each cube I want to draw, calling the template (i hope that makes sense) and using bufferdata to update that template for every location, do I have to actually store those 24 vectors for every single location in the 16x16x16, or would I just store the map coordinates, then have the cube and polygons drawn through a shader?

I hope that makes sense. it seems expensive memory wise loading up something that stores 24 vectors per location, and it seems resource intensive to me calling bufferdata 16x16x16 times per frame... so the last option using the vertex shader seems the most viable, but I'm new to shaders so is something like that possible?

What is the most common method used?

Answer 1

Geometry shaders can, indeed, emit multiple primitives for a single input primitive. So drawing all 6 faces of a cube from a single input point is certainly possible. Though for "voxel" engines you might be better served by point sprites, as often the orientation of the cube isn't useful. A point sprite draws a single screen-aligned quad from an input point. Beyond that you'll need to be more specific about what you're doing.