Lunatic: add 'geom' module, sporting a vec2 type and a general 'intersect' func.

git-svn-id: https://svn.eduke32.com/eduke32@2855 1a8010ca-5511-0410-912e-c29ae57300e0

polymer/eduke32/Makefile

@@ -165,7 +165,8 @@ ifneq (0,$(LUNATIC))
 
     GAMEOBJS+= $(OBJ)/../lpeg.$o  # TEMP
     GAMEOBJS+= $(OBJ)/luaJIT_BC_con_lang.$o \
-               $(OBJ)/luaJIT_BC_lunacon.$o
+               $(OBJ)/luaJIT_BC_lunacon.$o \
+               $(OBJ)/luaJIT_BC_geom.$o
 
     # now, take care of having the necessary symbols (sector, wall, etc.) in the
     # executable no matter what the debugging level

polymer/eduke32/source/lunatic/defs.ilua

@@ -525,6 +525,12 @@ string.dump = nil
 
 local allowed_modules = {
     coroutine=coroutine, bit=bit, table=table, math=math, string=string,
+
+    os = {
+        clock = function() return gv_.gethitickms()/1000 end,
+    },
+
+    geom = require("geom"),
 }
 
 local package_loaded = {}

polymer/eduke32/source/lunatic/dynsymlist

@@ -40,6 +40,7 @@ g_player;
 
 luaJIT_BC_lunacon;
 luaJIT_BC_con_lang;
+luaJIT_BC_geom;
 
 gethitickms;
 };

polymer/eduke32/source/lunatic/geom.lua

@@ -0,0 +1,94 @@
+-- Geometry module for Lunatic.
+
+local ffi = require("ffi")
+local math = require("math")
+
+local type = type
+local assert = assert
+
+
+module(...)
+
+
+ffi.cdef[[
+typedef struct { double x, y; } dvec2_t;
+]]
+
+local vec2_
+local mt = {
+    __add = function(a, b) return vec2_(a.x+b.x, a.y+b.y) end,
+    __sub = function(a, b) return vec2_(a.x-b.x, a.y-b.y) end,
+    __unm = function(a) return vec2_(-a.x, -b.x) end,
+
+    __mul = function(a,b)
+        if (type(a)=="number") then
+            return vec2_(a*b.x, a*b.y)
+        end
+
+        assert(type(b)=="number")
+        return vec2_(a.x*b, a.y*b)
+    end,
+
+    __div = function(a,b)
+        assert(type(b)=="number")
+        return vec2_(a.x/b, a.y/b)
+    end,
+
+    __eq = function(a,b)
+        return (a.x==b.x and a.y==b.y)
+    end,
+
+    __len = function(a) return math.sqrt(a.x*a.x + a.y*a.y) end,
+
+    __tostring = function(a) return "vec2("..a.x..", "..a.y..")" end,
+
+    __index = {
+        lensq = function(a) return a.x*a.x + a.y*a.y end,
+    },
+}
+
+-- VEC2 user data constructor.
+--  * vec2(<table or ctype>), the arg should be indexable with "x" and "y"
+--  * vec2(x, y), assuming that x and y are numbers
+vec2_ = ffi.metatype("dvec2_t", mt)
+vec2 = vec2_
+
+-- Returns a vec2 from anything indexable with "x" and "y"
+-- (vec2(t) works if t is such a table, but not if it's a vec2)
+function tovec2(t)
+    return vec2(t.x, t.y)
+end
+
+-- Two-element vector cross product.
+-- Anti-commutative, distributive.
+function cross2(v, w)
+    return v.y*w.x - v.x*w.y
+end
+
+
+-- Finds the intersection point of two lines given by
+-- point a and vector v
+--  and
+-- point b and vector w
+--
+-- Returns:
+--  if <TODO>, nil
+--  if retpoint_p evaluates to a non-true value, coefficients cv and cw such that <TODO>
+--  else, the intersection point
+function intersect(a,v, b,w, retpoint_p)
+    local vxw = cross2(v,w)
+
+    if (vxw ~= 0) then
+        local btoa = tovec2(a)-tovec2(b)
+        local cv, cw = cross2(w, btoa)/vxw, cross2(v, btoa)/vxw
+
+        if (retpoint_p) then
+            return tovec2(a)+cv*tovec2(v)
+        else
+            return cv, cw
+        end
+    end
+
+    -- return nil if v and w parallel (or either of them is a point), or if
+    -- they contain NaNs
+end

polymer/eduke32/source/lunatic/test.elua

@@ -249,6 +249,8 @@ printf("EVENT_INIT = %d", gv.EVENT_INIT)  -- tests default defines
 local bittest = require "bittest"
 bittest.sieve()
 
+require("test/test_geom")
+
 print('---=== END TEST SCRIPT ===---')
 
 -- This will complain about wrong usage of 'error'. In particular,

polymer/eduke32/source/lunatic/test/test_geom.lua

@@ -0,0 +1,41 @@
+#!/usr/bin/env luajit
+
+local math = require("math")
+local os = require("os")
+
+local geom = require("geom")
+
+
+local N = os.exit and tostring(arg[1]) or 1e6
+
+local A,B = {}, {}
+local V,W = {}, {}
+
+local function randvec()
+    return geom.vec2(math.random(), math.random())
+end
+
+local t1 = os.clock()
+
+-- init random points and vectors
+for i=1,N do
+    A[i] = randvec()
+    B[i] = randvec()
+    V[i] = randvec()
+    W[i] = randvec()
+end
+
+local t2 = os.clock()
+
+local v = geom.vec2(0, 0)
+for i=1,N do
+    v = v + geom.intersect(A[i],V[i], B[i],W[i], true)
+end
+
+local t3 = os.clock()
+
+print(1000*(t2-t1))
+print(1000*(t3-t2))
+print(v)
+
+return {}  -- appease Lunatic's require