// Set the river tile at the given corner position (and wrapped
// positions if necessary)
protected virtual void SetRiverTile(int x, int y, RiverTile tile)
{
currentRiverMap.SetTile(new Vector3Int(x, y, 0), tile);
// If the river is on a wrapping edge, place the same river tile on
// the opposite side
bool wrapX =
parameters.WrapX && (x == 0 || x == parameters.Width);
bool wrapY =
parameters.WrapY && (y == 0 || y == parameters.Height);
if (wrapX)
{
// Horizontally
currentRiverMap.SetTile(
new Vector3Int(parameters.Width - x, y, 0), tile);
}
if (wrapY)
{
// Vertically
currentRiverMap.SetTile(
new Vector3Int(x, parameters.Height - y, 0), tile);
}
if (wrapX && wrapY)
{
// Corner wrapping in both dimensions
currentRiverMap.SetTile(
new Vector3Int(parameters.Width - x,
parameters.Height - y, 0), tile);
}
}
// Place rivers on the map
protected virtual void GenerateRivers()
{
// In non-wrapping dimensions, there are more corners than tiles
int cornersWidth = parameters.Width;
if (!parameters.WrapX)
{
cornersWidth++;
}
int cornersHeight = parameters.Height;
if (!parameters.WrapY)
{
cornersHeight++;
}
// Check all tile corners
for (int i = 0; i < cornersHeight; i++)
{
for (int j = 0; j < cornersWidth; j++)
{
// Try to get the river tile at the corner
RiverTile currentCorner =
currentRiverMap.GetTile <RiverTile>(
new Vector3Int(j, i, 0));
// Skip if there is already a river here or if next to
// ocean
if (currentCorner || CornerAtOcean(j, i))
{
continue;
}
// Certain probability of starting river
if (Random.value < RiverProbability(j, i))
{
ContinueRiver(j, i, 0);
}
}
}
}
// Place a river at the given corner, then determine the next corner in
// the river and, if necessary, call this function for that corner
// prevDirection is the direction that the previous corner is in
protected virtual void ContinueRiver(
int x, int y, RiverTile.Directions prevDirection)
{
// Create the new river tile and set its connection to the previous
// one
RiverTile newTile = ScriptableObject.CreateInstance <RiverTile>();
newTile.Parameters = parameters;
newTile.LandTilemap = currentMap;
newTile.Connections = prevDirection;
// Stop if reached ocean
if (!CornerAtOcean(x, y))
{
// Next river tile is down the steepest downslope
int nextX, nextY;
SteepestSlope(x, y, out nextX, out nextY);
// Stop if there is no downslope
if (nextX != -1 && nextY != -1)
{
// Try to get existing river tile at next position
RiverTile nextCorner = currentRiverMap.GetTile <RiverTile>(
new Vector3Int(nextX, nextY, 0));
// Check direction of next river tile
// Left
if (nextX < x)
{
// Set connection to the next river tile
newTile.Connections |= RiverTile.Directions.Left;
// If next river tile already exists, set its
// connection to the current tile and stop
if (nextCorner)
{
nextCorner.Connections |=
RiverTile.Directions.Right;
}
// Recursively continue river generation
else
{
ContinueRiver(
nextX, nextY, RiverTile.Directions.Right);
}
}
// Right
else if (nextX > x)
{
newTile.Connections |= RiverTile.Directions.Right;
if (nextCorner)
{
nextCorner.Connections |=
RiverTile.Directions.Left;
}
else
{
ContinueRiver(
nextX, nextY, RiverTile.Directions.Left);
}
}
// Up
else if (nextY > y)
{
newTile.Connections |= RiverTile.Directions.Up;
if (nextCorner)
{
nextCorner.Connections |=
RiverTile.Directions.Down;
}
else
{
ContinueRiver(
nextX, nextY, RiverTile.Directions.Down);
}
}
// Down
else if (nextY < y)
{
newTile.Connections |= RiverTile.Directions.Down;
if (nextCorner)
{
nextCorner.Connections |=
RiverTile.Directions.Up;
}
else
{
ContinueRiver(
nextX, nextY, RiverTile.Directions.Up);
}
}
// Replace next corner with updated connections
if (nextCorner)
{
SetRiverTile(nextX, nextY, null);
SetRiverTile(nextX, nextY, nextCorner);
}
}
}
SetRiverTile(x, y, newTile);
}