tasks a-s

Task/Ray-casting-algorithm/Factor/ray-casting-algorithm-1.factor

@@ -0,0 +1,19 @@
+USING: kernel prettyprint sequences arrays math math.vectors ;
+IN: raycasting
+
+: between ( a b x -- ? ) [ last ] tri@ [ < ] curry bi@ xor ;
+
+: lincomb ( a b x -- w )
+  3dup [ last ] tri@
+  [ - ] curry bi@
+  [ drop ] 2dip
+  neg 2dup + [ / ] curry bi@
+  [ [ v*n ] curry ] bi@ bi*  v+ ;
+: leftof ( a b x -- ? ) dup [ lincomb ] dip [ first ] bi@ > ;
+
+: ray ( a b x -- ? ) [ between ] [ leftof ] 3bi and ;
+
+: raycast ( poly x -- ? )
+  [ dup first suffix [ rest-slice ] [ but-last-slice ] bi ] dip
+  [ ray ] curry 2map
+  f [ xor ] reduce ;