3D Game Geometry?

Question

I have a simple game that uses a 3D grid representation, something like: Blocks grid[10][10][10]; The person in the game is represented by a point and a sight vector: double x,y,z, dx,dy,dz; I draw the grid with 3 nested for loops: for(...) for(...) for(...) draw(grid[i][j][k]); The obvious problem with this is when the size of the grid grows within the hundreds, fps drop dramatically. With some intuition, I realized that: - Blocks that were hidden by other blocks in the grid don't need to be rendered - Blocks that were not within the person's vision field also don't need to be rendered (ie. blocks that were behind the person) My question is, given a `grid[][][]`, a person's `x,y,z`, and a sight vector `dx,dy,dz`, how could I figure out which blocks need to be rendered and which don't?

Answer 1

It would be safe to say that if dx>0 then anything less than dx need not be rendered, since the player

does not have eyes in the back of their head.

LIkewise, anything less than dy may not necessarily visible either.

If the player can look left at right then the peripheral vision is within the range (-dz, dz) in the clockwise direction. So if the -dz is at pi/2 and dz is at -pi/2 then anything in the interval (pi/2, 3 * pi/2) need not be rendered either.