Fix offsets with AddToValue, tweak slides

data/DrivingCodeWithData.cakedata

@@ -37,9 +37,10 @@ for each iceStorm in iceStorms:
 {
     updateIceStorm(iceStorm);
 }")
-  (slide-data :heading "We want" :body "slime sling
-laser blast
+  (slide-data :heading "We want" :body "rock smash
+magma ball
 heat seeker
+boomerang
 ...")
   (slide-data :heading "We have a problem")
   (slide-data :heading "Second pass: sharing code"
@@ -303,14 +304,5 @@ is hard.
 
 That doesn't mean it shouldn't be done, but does
 mean it should be done carefully.")
-  (slide-data :heading "In conclusion"
-              :body "Doing this is not hard,
-knowing when to do this, and to what extent,
-is hard.
-
-That doesn't mean it shouldn't be done, but does
-mean it should be done carefully.
-
-Using data to drive code is powerful.")
   (slide-data :heading "Questions?"
               :trigger "random-power-cycle"))

data/PowerSystem.cakedata

@@ -72,6 +72,7 @@ SetValue velocityX 25"
   IfGreaterThanOrEqual positionX enemyX
     PlayEffect smoke-explosion smoke-explosion-idle
     SetValue velocityX 0
+    AddToValue positionY -65
     DamageEnemy
     Expire
   End
@@ -104,7 +105,8 @@ End")
   (power
    :id "iceStorm"
    :on-create "PlayEffect ice-explosion ice-explosion-flying
-SetValue velocityX 10"
+SetValue velocityX 10
+AddToValue positionY -50"
   :on-update
   "IfGreaterThanOrEqual velocityX 2
   IfGreaterThanOrEqual positionX enemyX
@@ -133,13 +135,14 @@ SetValue velocityX 20"
   IfGreaterThanOrEqual positionX enemyX
     PlayEffect explosion explosion-fast
     SetValue velocityX 0
+    AddToValue positionY -45
     DamageEnemy
     Expire
   End
 End
 IfEquals user0 0
   IfGreaterThanOrEqual lifetimeFrameCount 2
-    SetValue relativeSpawnY -35
+    SetValue relativeSpawnY -45
     SpawnPower explosion
     SetValue user0 1
   End
@@ -195,8 +198,8 @@ End")
    :id "rocks"
    :on-create "PlayEffect rocks rocks-fall
 SetValue positionX enemyX
-SetValue positionY 610
-SetValue positionY 410
+SetValue positionY enemyY
+AddToValue positionY -210
 Expire"
    :on-update "IfGreaterThanOrEqual lifetimeFrameCount 6
     DamageEnemy

src/Presentation.cake

@@ -237,6 +237,7 @@
   operation-type-spawn-power
 
   operation-type-set-value
+  operation-type-add-to-value
 
   operation-type-if-equals
   operation-type-if-string-equals
@@ -278,6 +279,9 @@
      (array
       operation-type-set-value
       "SetValue" 2)
+     (array
+      operation-type-add-to-value
+      "AddToValue" 2)
      (array
       operation-type-if-equals
       "IfEquals" 2)
@@ -735,6 +739,15 @@
          ;; (preslog "Setting %s to %s\n" (path op > string-a) (path op > string-b))
            (set (deref value-out) (deref set-value-to))
            (preslog "Failed to set %s to %s (not bound)\n" (path op > string-a) (path op > string-b))))
+      ((= (path op > type) operation-type-add-to-value)
+       (var value-out (* int) (resolve-value-from-name
+                               context (path op > string-a)))
+       (var add-value (* int) (resolve-value-or-literal-from-string
+                                  context (path op > string-b)))
+       (if (and value-out add-value)
+         ;; (preslog "Setting %s to %s\n" (path op > string-a) (path op > string-b))
+           (set (deref value-out) (+ (deref value-out) (deref add-value)))
+           (preslog "Failed to add to %s %s (not bound)\n" (path op > string-a) (path op > string-b))))
       ((= (path op > type) operation-type-if-equals)
        (var value-a (* int) (resolve-value-or-literal-from-string
                              context (path op > string-a)))