WOP

apps/find_plane.lua

@@ -0,0 +1,52 @@
+local apps       = require 'apps.apps'
+local ask        = require('dialog.input').display_sync
+local choice     = require('dialog.choice').display_sync
+local expr       = require 'expressiontree'
+
+local function table_to_vec(t)
+   local r = ""
+   for _, v in ipairs(t) do
+      r = r .. "[" .. v .. "]"
+   end
+   return "[" .. r .. "]"
+end
+
+local function ask_vector(title, dim)
+   dim = dim or 3
+   while true do
+      local r = ask({title = title or 'Vector'})
+      if not r then
+         return nil
+      end
+
+      local v = {}
+      for c in r:gmatch("([^,]+)") do
+         table.insert(v, c)
+      end
+
+      if #v == dim then
+         return v
+      end
+   end
+end
+
+local function run_plane_3pt(stack)
+   local pts = {}
+   for i = 1, 3 do
+      local pt = ask_vector("Point " .. tostring(i))
+      if not pt then
+         return
+      end
+      table.insert(pts, pt)
+   end
+
+   local a, b, c = pts[1], pts[2], pts[3]
+   local ab = math.evalStr(table_to_vec(a) .. "-" .. table_to_vec(b))
+   local ac = math.evalStr(table_to_vec(a) .. "-" .. table_to_vec(c))
+   local n = math.evalStr("crossp(" .. ab .. "," .. ac .. ")")
+   local eq = math.evalStr("dotp(" ..n .. "," .. table_to_vec({"x", "y", "z"}) .. ")")
+   local d = math.evalStr(string.format(eq .."|(x=%s and y=%s and z=%s)", a[1], a[2], a[3]))
+   stack:push_infix(eq .. "=" .. d)
+end
+
+apps.add('plane - 3pt', 'Plane - 3 Points', run_plane_3pt)

apps/init.lua

@@ -4,3 +4,5 @@ require 'apps.app_punktsteigung'
 require 'apps.app_triangle'
 require 'apps.app_constants'
 require 'apps.app_analyze_fn'
+
+require 'apps.find_plane'