GetCell(x, y+1)->m_type = WATER // we now update the new state choose random dir if both are possible Void Simulation::update_water(int x, int y)īool down = (getOldCell(x, y+1)->m_type = EMPTY) & checkBounds(x, y+1) & !getOldCell(x, y+1)->m_visited īool d_left = (getOldCell(x-1, y+1)->m_type = EMPTY) & checkBounds(x-1, y+1) & !getOldCell(x-1, y+1)->m_visited īool d_right = (getOldCell(x+1, y+1)->m_type = EMPTY) & checkBounds(x+1, y+1) & !getOldCell(x+1, y+1)->m_visited īool left = (getOldCell(x-1, y)->m_type = EMPTY) & checkBounds(x-1, y) & !getOldCell(x-1, y)->m_visited īool right = (getOldCell(x+1, y)->m_type = EMPTY) & checkBounds(x+1, y) & !getOldCell(x+1, y)->m_visited If(c->m_visited = false) update_water(x, y) If(c->m_visited = false) update_sand(x, y)

I've been testing it all morning and have yet to find a solution, I thought it might've been someting to do with how I was copying the arrays over, but it seems to work as far as I can tell.ĬopyStates(m_cells, m_oldCells) // so now oldcells is the last new state This already made the sand work better, however water, which checks horizontally for free cells, now 'disappears' when it does move horizontally. Ok so I've made a little progress, however I've ran into another bug that seems to be unrelated to iteration, since now I save a copy of the old cells and read from that to decide an update, then update the original cells and display that. Has anyone faced any similar challeneges in developing a simulation like this, or knows something that I'm missing? Any help would be very much appreciated. I initially thought it was a problem with how I marked the cells as processed but I've found no obvious bugs with that system in many hours of testing. This effect is reversed whenever I iterate left-to-right, so I know it's something to do with that but so far I've been stumped trying to fix it. So instead of forming a nice triangular shape flowing out evenly to both sides, the whole shape will just move to the left. My problem is a sort of 'left-bias' in how the particles move if I spawn a square of water cells above a barrier, they will basically all shift to left without moving once the particles begin to reach the barrier, while the cells on the right will run down in the proper way. I then mark the cell it moved into as processed so that it is not checked again for the rest of that loop. I basically have a grid of cells that I iterate through bottom-to-top, left-to-right and if I find a water cell, I just check below, down to left, down to the right, left then right for empty cells and it moves into the first one its finds (it makes a random choice if both diagonal cells or both horizontal cells are free). I am currently working on a very simple 'Falling Sand' simulation game in C++ and SDL2, and am having problems with getting water to flow in a more realistic manner.

Falling sand 3