mtcontrib/mapgen_rivers
1
0
Fork 0
mirror of https://gitlab.com/gaelysam/mapgen_rivers.git synced 2025-06-30 23:40:55 +02:00
Code Issues Projects Releases Wiki Activity

Reverse axes order for heightmaps (iterate in Z direction first instead of X)

Browse Source
This commit is contained in:
Gaël de Sailly
2020-07-21 12:46:23 +02:00
parent 6f43430574
commit 25c5cb2e1f
3 changed files with 41 additions and 40 deletions
Download Patch File Download Diff File Expand all files Collapse all files

56
polygons.lua
View File

@ -96,7 +96,7 @@ local function make_polygons(minp, maxp)
init = true
end
local chulens = maxp.z - minp.z + 1
local chulens = maxp.x - minp.x + 1
local polygons = {}
-- Determine the minimum and maximum coordinates of the polygons that could be on the chunk, knowing that they have an average size of 'blocksize' and a maximal offset of 0.5 blocksize.
@ -115,44 +115,44 @@ local function make_polygons(minp, maxp)
local poly_z = {offset_z[iA]+zp, offset_z[iB]+zp, offset_z[iC]+zp+1, offset_z[iD]+zp+1}
local polygon = {x=poly_x, z=poly_z, i={iA, iB, iC, iD}}
local bounds = {} -- Will be a list of the intercepts of polygon edges for every X position (scanline algorithm)
-- Calculate the min and max X positions
local xmin = math.max(math.floor(blocksize*math.min(unpack(poly_x)))+1, minp.x)
local xmax = math.min(math.floor(blocksize*math.max(unpack(poly_x))), maxp.x)
local bounds = {} -- Will be a list of the intercepts of polygon edges for every Z position (scanline algorithm)
-- Calculate the min and max Z positions
local zmin = math.max(math.floor(blocksize*math.min(unpack(poly_z)))+1, minp.z)
local zmax = math.min(math.floor(blocksize*math.max(unpack(poly_z))), maxp.z)
-- And initialize the arrays
for x=xmin, xmax do
bounds[x] = {}
for z=zmin, zmax do
bounds[z] = {}
end
local i1 = 4
for i2=1, 4 do -- Loop on 4 edges
local x1, x2 = poly_x[i1], poly_x[i2]
-- Calculate the integer X positions over which this edge spans
local lxmin = math.floor(blocksize*math.min(x1, x2))+1
local lxmax = math.floor(blocksize*math.max(x1, x2))
if lxmin <= lxmax then -- If there is at least one position in it
local z1, z2 = poly_z[i1], poly_z[i2]
-- Calculate coefficient of the equation defining the edge: Z=aX+b
local a = (z1-z2) / (x1-x2)
local b = blocksize*(z1 - a*x1)
for x=math.max(lxmin, minp.x), math.min(lxmax, maxp.x) do
-- For every X position involved, add the intercepted Z position in the table
table.insert(bounds[x], a*x+b)
local z1, z2 = poly_z[i1], poly_z[i2]
-- Calculate the integer Z positions over which this edge spans
local lzmin = math.floor(blocksize*math.min(z1, z2))+1
local lzmax = math.floor(blocksize*math.max(z1, z2))
if lzmin <= lzmax then -- If there is at least one position in it
local x1, x2 = poly_x[i1], poly_x[i2]
-- Calculate coefficient of the equation defining the edge: X=aZ+b
local a = (x1-x2) / (z1-z2)
local b = blocksize*(x1 - a*z1)
for z=math.max(lzmin, minp.z), math.min(lzmax, maxp.z) do
-- For every Z position involved, add the intercepted X position in the table
table.insert(bounds[z], a*z+b)
end
end
i1 = i2
end
for x=xmin, xmax do
for z=zmin, zmax do
-- Now sort the bounds list
local xlist = bounds[x]
table.sort(xlist)
local c = math.floor(#xlist/2)
local zlist = bounds[z]
table.sort(zlist)
local c = math.floor(#zlist/2)
for l=1, c do
-- Take pairs of Z coordinates: all positions between them belong to the polygon.
local zmin = math.max(math.floor(xlist[l*2-1])+1, minp.z)
local zmax = math.min(math.floor(xlist[l*2]), maxp.z)
local i = (x-minp.x) * chulens + (zmin-minp.z) + 1
for z=zmin, zmax do
-- Take pairs of X coordinates: all positions between them belong to the polygon.
local xmin = math.max(math.floor(zlist[l*2-1])+1, minp.x)
local xmax = math.min(math.floor(zlist[l*2]), maxp.x)
local i = (z-minp.z) * chulens + (xmin-minp.x) + 1
for x=xmin, xmax do
-- Fill the map at these places
polygons[i] = polygon
i = i + 1