Make the skull animations smooth

This moves skulls into their own class - Hole (just like the original code for Zuma), and it borrows code from UIWidgetSpriteProgress.

Contributes to issue #9

src/Hole.lua

@@ -0,0 +1,91 @@
+local class = require "com.class"
+
+---@class Hole
+---@overload fun(params):Hole
+local Hole = class:derive("Hole")
+
+local Vec2 = require("src.Essentials.Vector2")
+
+
+
+--[[
+    !! READ BEFORE IMPLEMENTING THIS TO UPSTREAM !!
+
+    This fork-specific class has hardcoded values. De-hardcode and allow for
+    customization before implementing to upstream.
+
+    This only allows for smooth movement of the top sprite. Consider the following
+    prior to implementing this class to upstream:
+    - allow ZD-style skull animations (sprite states)
+    - allow multiple animations/sprite positions
+    - allow multiple effects
+    - etc...
+]]
+
+---Initializes a new Hole.
+---@param path Path
+function Hole:new(path)
+    self.path = path
+    self.pos = Vec2.round(path.nodes[#path.nodes].pos)
+
+    self.skullHoleSprite = _Game.resourceManager:getSprite("sprites/game/skull_hole.json")
+    self.skullMaskSprite = _Game.resourceManager:getSprite("sprites/game/skull_mask.json")
+    self.skullFrameSprite = _Game.resourceManager:getSprite("sprites/game/skull_frame.json")
+    self.skullTopSprite = _Game.resourceManager:getSprite("sprites/game/skull_top.json")
+    self.skullBottomSprite = _Game.resourceManager:getSprite("sprites/game/skull_bottom.json")
+    self.skullMaskShader = love.graphics.newShader [[
+        vec4 effect(vec4 color, Image texture, vec2 texture_coords, vec2 screen_coords) {
+            if (Texel(texture, texture_coords).rgb == vec3(0.0)) {
+                // a discarded pixel wont be applied as the stencil.
+                discard;
+            }
+            return vec4(1.0);
+        }
+    ]]
+
+    self.topSpriteOffset = 0
+    -- the bottom sprite doesn't move
+end
+
+
+
+function Hole:update(dt)
+    local dangerProgress = self.path:getDangerProgress()
+
+    -- top sprite
+    local topSpriteOffsetBuffer = dangerProgress*20
+    if self.topSpriteOffset < topSpriteOffsetBuffer then
+        self.topSpriteOffset = math.min(self.topSpriteOffset + 20 * dt, topSpriteOffsetBuffer)
+    elseif self.topSpriteOffset > topSpriteOffsetBuffer then
+        self.topSpriteOffset = math.max(self.topSpriteOffset - 4 * dt, topSpriteOffsetBuffer)
+    end
+
+    -- ring of fire
+    -- the ring of fire uses some sort of animation that changes depending on the state,
+    -- an opacity value won't do
+end
+
+
+
+function Hole:draw()
+    self.skullHoleSprite:draw(self.pos, Vec2(0.5,0.5))
+    love.graphics.stencil(function()
+        love.graphics.setShader(self.skullMaskShader)
+        self.skullMaskSprite:draw(self.pos, Vec2(0.5,0.5))
+        love.graphics.setShader()
+    end, "replace", 1)
+    love.graphics.setStencilTest("greater", 0)
+
+    local skullTopPos = Vec2(self.pos.x, (self.pos.y-3) - self.topSpriteOffset)
+    local skullBotPos = Vec2(self.pos.x, self.pos.y+10)
+
+    self.skullTopSprite:draw(skullTopPos, Vec2(0.5,0.5))
+    self.skullBottomSprite:draw(skullBotPos, Vec2(0.5, 0.5))
+
+    love.graphics.setStencilTest()
+    self.skullFrameSprite:draw(self.pos, Vec2(0.5,0.5))
+end
+
+
+
+return Hole

src/Map.lua

@@ -8,6 +8,7 @@ local Vec2 = require("src.Essentials.Vector2")
 local Sprite = require("src.Essentials.Sprite")
 
 local Path = require("src.Path")
+local Hole = require("src.Hole")
 
 
 
@@ -42,29 +43,11 @@ function Map:new(level, path, pathsBehavior, isDummy)
 	end
     self.shooter = data.shooter
     self.targetPoints = data.targetPoints
-
-	-- FORK-SPECIFIC CODE:
-	-- Skulls. SPRITES ARE HARDCODED, DE-HARDCODE FIRST AND ALLOW FOR
-    -- CUSTOMIZATION BY THE MODDER IF THIS IS TO BE IMPLEMENTED TO UPSTREAM.
-	self.skullHoleSprite = _Game.resourceManager:getSprite("sprites/game/skull_hole.json")
-	self.skullMaskSprite = _Game.resourceManager:getSprite("sprites/game/skull_mask.json")
-	self.skullFrameSprite = _Game.resourceManager:getSprite("sprites/game/skull_frame.json")
-	self.skullTopSprite = _Game.resourceManager:getSprite("sprites/game/skull_top.json")
-	self.skullBottomSprite = _Game.resourceManager:getSprite("sprites/game/skull_bottom.json")
-	self.skullMaskShader = love.graphics.newShader[[
-		vec4 effect(vec4 color, Image texture, vec2 texture_coords, vec2 screen_coords) {
-			if (Texel(texture, texture_coords).rgb == vec3(0.0)) {
-				// a discarded pixel wont be applied as the stencil.
-				discard;
-			}
-			return vec4(1.0);
-		}
-		]]
-
-    self.skullPoints = {}
-    for _, path in pairs(self.paths) do
-		local lastPoint = path.nodes[#path.nodes].pos
-        table.insert(self.skullPoints, Vec2.round(lastPoint))
+
+	---@type Hole[]
+    self.holes = {}
+    for _, pathp in pairs(self.paths) do
+		table.insert(self.holes, Hole(pathp))
     end
 end
 
@@ -129,28 +112,11 @@ function Map:draw()
             end
         end
     end
-
-	-- FORK-SPECIFIC CODE: skull rendering goes here
-	-- i took this from the love2d page is this a dirty way to do it
-	for i, pos in pairs(self.skullPoints) do
-		self.skullHoleSprite:draw(pos, Vec2(0.5,0.5))
-		love.graphics.stencil(function()
-			love.graphics.setShader(self.skullMaskShader)
-			self.skullMaskSprite:draw(pos, Vec2(0.5,0.5))
-			love.graphics.setShader()
-		end, "replace", 1)
-        love.graphics.setStencilTest("greater", 0)
-
-		local skullTopPos = Vec2(pos.x, (pos.y-3) - (self.paths[i]:getDangerProgress()*20))
-        local skullBotPos = Vec2(pos.x, pos.y+10)
-
-		self.skullTopSprite:draw(skullTopPos, Vec2(0.5,0.5))
-        self.skullBottomSprite:draw(skullBotPos, Vec2(0.5, 0.5))
-
-        love.graphics.setStencilTest()
-		self.skullFrameSprite:draw(pos, Vec2(0.5,0.5))
+
+    -- Holes
+	for _, hole in pairs(self.holes) do
+		hole:draw()
 	end
-	-- END FORK-SPECIFIC CODE
 end
 
 

src/Path.lua

@@ -138,6 +138,11 @@ function Path:update(dt)
 		if scorpion.delQueue then table.remove(self.scorpions, i) end
 	end
 
+    -- Holes
+	for _, hole in pairs(self.map.holes) do
+		hole:update(dt)
+	end
+
 	-- Path Clears
     if self:isValidForCurveClear() then
 		self.pathClearGranted = true