1.add max sub array problem algorithm

2.add hit info storage in raytracer1.jl

Author: bhz

find_max_subarray.jl

@@ -0,0 +1,50 @@
+# max sub array problem
+function findMaxCrossingSubarray(A,low,mid,high)
+    left_sum = typemin(Float64)
+    sum = 0
+    max_left = 1
+    for i=[mid:-1:low]
+        sum += A[i]
+        if sum>left_sum
+            left_sum = sum
+            max_left = i
+        end
+    end
+    right_sum = typemin(Float64)
+    sum = 0
+    max_right = 1
+    for j=[mid+1:high]
+        sum += A[j]
+        if sum>right_sum
+            right_sum = sum
+            max_right = j
+        end
+    end
+    return max_left,max_right,left_sum+right_sum
+end
+
+function findMaxSubarray(A,low,high)
+    if high == low
+        return low,high,A[low]
+    else
+        mid = floor((low+high)/2)
+        left_low,left_high,left_sum = findMaxSubarray(A,low,mid)
+        right_low,right_high,right_sum = findMaxSubarray(A,mid+1,high)
+        cross_low,cross_high,cross_sum = findMaxCrossingSubarray(A,low,mid,high)
+        if left_sum>right_sum && left_sum>cross_sum
+            return left_low,left_high,left_sum
+        elseif right_sum>left_sum && right_sum>cross_sum
+            return right_low,right_high,right_sum
+        else
+            return cross_low,cross_high,cross_sum
+        end
+    end
+end
+
+function test()
+    arr = [13,-3,-25,20,-3,-16,-23,18,20,-7,12,-5,-22,15,-4,7]
+    low,high,sum = findMaxSubarray(arr,1,length(arr))
+    println(low)
+    println(high)
+    println(sum)
+end

raytracer1.jl

@@ -1,9 +1,18 @@
+# 光线
 type Ray
     o::Vector{Float64}
     d::Vector{Float64}
     Ray(o,d)=if length(o)!=3 || length(d)!=3; error("only 3d"); else; new(o,d); end
 end
 
+# 存储交点信息
+type ShadeRec
+    n::Vector{Float64}
+    hitp::Vector{Float64}
+    ShadeRec(n,hitp)=if length(hitp)!=3 || length(n)!=3; error("only 3d"); else; new(n,hitp); end
+end
+
+# 无限平面
 type Plane
     p::Vector{Float64}
     n::Vector{Float64}
@@ -12,21 +21,29 @@ type Plane
 end
 Plane(p,n) = Plane(p,n,0.0)
 
+# 平面相交测试
 function hit(pln::Plane, ray::Ray)
     t=dot((pln.p-ray.o),pln.n)/(dot(ray.d,pln.n))
     if t>pln.kEps
-        return true
+        sr = ShadeRec(ray.o+t*ray.d,pln.n)
+        return true, sr # 相交时返回交点信息
     else
         return false
     end
 end
 
+# 世界
+
+
+# 视平面
+
+
 function test()
     pln = Plane([0,0,-20.0],[0,0,1.0])
     ray1 = Ray([0,0,0],[0,0,-1])
     ray2 = Ray([0,0,0],[1,0,0])
     ray3 = Ray([0,0,0],[0,1,0])
-    hit(pln,ray1)?println("hit"):println("not hit")
-    hit(pln,ray2)?println("hit"):println("not hit")
-    hit(pln,ray3)?println("hit"):println("not hit")
+    hit(pln,ray1)[1]?println("hit"):println("not hit")
+    hit(pln,ray2)[1]?println("hit"):println("not hit")
+    hit(pln,ray3)[1]?println("hit"):println("not hit")
 end