From b183c489ee90f61f9aa0b5e65ab95b07a5fae17f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tom=C3=A1=C5=A1=20Brada?= <tomasbrod@azet.sk>
Date: Sun, 10 May 2015 16:05:48 +0200
Subject: [PATCH] Sample cubic bezier vein generator.

---
 rocks/veins.lua | 38 ++++++++++++++++++++++++++------------
 1 file changed, 26 insertions(+), 12 deletions(-)

diff --git a/rocks/veins.lua b/rocks/veins.lua
index fd2ab79..1679d82 100644
--- a/rocks/veins.lua
+++ b/rocks/veins.lua
@@ -1,28 +1,42 @@
 -- experimental fast vein generator
 
+local pr
+
 rocksl.genvein=function(minp,maxp,seed,vm,area)
  local t1 = os.clock()
  local data = vm:get_data()
 
- local chunksize = maxp.x - minp.x + 1
+ local chunksizer = maxp.x - minp.x + 1
+ local chunksize = chunksizer + 1
  local pmapsize = {x = chunksize, y = chunksize, z = chunksize}
  local minpxz = {x = minp.x, y = minp.z}
- local pr=PseudoRandom(seed)
+ pr=pr or PseudoRandom(seed)
  local c_sample=minetest.get_content_id("default:mese")
+ local sample_scarcity=8
  
- local numveins_raw=(chunksize/8)
- local numveins = numveins_raw + (pr:next(-100,100)/100)
- local numveins = 1
- print("numveins="..numveins)
+ local numveins_raw=(chunksize/sample_scarcity)
+ local numveins = math.floor(numveins_raw + (pr:next(0,99)/100))
+ print("numveins="..numveins.." raw="..numveins_raw)
+ print("pr="..pr:next().." seed="..seed)
+ print("minp="..minp.x..","..minp.y..","..minp.z)
+ print("maxp="..maxp.x..","..maxp.y..","..maxp.z)
+ --local pointA=vector.add(minp,chunksize/2)
+ local pointA=vector.new(pr:next(0,chunksizer)+minp.x,pr:next(0,chunksizer)+minp.y,pr:next(0,chunksizer)+minp.z)
 
  for vc=1, numveins do
-  local pointA=vector.new(pr:next(minp.x,maxp.x),pr:next(minp.x,maxp.x),pr:next(minp.x,maxp.x))
-  local pointB=vector.new(pr:next(minp.x,maxp.x),pr:next(minp.x,maxp.x),pr:next(minp.x,maxp.x))
-  local dir=vector.subtract(pointB,pointA)
-  local step=(1/vector.length(dir))
-  --vectorA=vector.add(pointA,minp)
+  --local pointA=vector.new(pr:next(0,chunksizer)+minp.x,pr:next(0,chunksizer)+minp.y,pr:next(0,chunksizer)+minp.z)
+  local pointB=vector.new(pr:next(0,chunksizer)+minp.x,pr:next(0,chunksizer)+minp.y,pr:next(0,chunksizer)+minp.z)
+  local pointC=vector.new(pr:next(0,chunksizer)+minp.x,pr:next(0,chunksizer)+minp.y,pr:next(0,chunksizer)+minp.z)
+  print("pointA="..pointA.x..","..pointA.y..","..pointA.z)
+  print("pointB="..pointB.x..","..pointB.y..","..pointB.z)
+  print("pointC="..pointC.x..","..pointC.y..","..pointC.z)
+  local step=1.41/(vector.distance(pointA,pointB)+vector.distance(pointB,pointC))
+  print("step="..step)
   for t=0, 1, step do
-   local p=vector.add(pointA, vector.multiply(dir,t) )
+   local p=vector.multiply(pointA,(1-t)^2)
+   p=vector.add(p, vector.multiply(pointB,2*t*(1-t)) )
+   p=vector.add(p, vector.multiply(pointC,t*t) )
+   --local p=vector.add(vector.multiply(pointA,(1-t)), vector.multiply(pointB,t) )
    p=vector.round(p)
    local di=area:index(p.x,p.y,p.z)
    data[di]=c_sample