[lua] Clipping fix, see #1219

spine-corona/main.lua

@@ -66,9 +66,9 @@ function loadSkeleton(atlasFile, jsonFile, x, y, scale, animation, skin)
   if atlasFile == "spineboy.atlas" then
     animationStateData:setMix("walk", "jump", 0.4)		
 		animationStateData:setMix("jump", "run", 0.4);
-		animationState:setAnimationByName(0, "portal", true)
-		-- local jumpEntry = animationState:addAnimationByName(0, "jump", false, 3)
-		-- animationState:addAnimationByName(0, "run", true, 0)
+		animationState:setAnimationByName(0, "walk", true)
+		local jumpEntry = animationState:addAnimationByName(0, "jump", false, 3)
+		animationState:addAnimationByName(0, "run", true, 0)
   elseif atlasFile == "raptor.atlas" then
 		--skeleton.vertexEffect = spine.JitterEffect.new(5, 5)
 		skeleton.vertexEffect = swirl
@@ -81,7 +81,7 @@ function loadSkeleton(atlasFile, jsonFile, x, y, scale, animation, skin)
 	return { skeleton = skeleton, state = animationState }
 end
 
-table.insert(skeletons, loadSkeleton("spineboy.atlas", "spineboy-pro.json", 240, 300, 0.4, "portal"))
+table.insert(skeletons, loadSkeleton("spineboy.atlas", "spineboy-pro.json", 240, 300, 0.4, "walk"))
 table.insert(skeletons, loadSkeleton("stretchyman.atlas", "stretchyman-stretchy-ik-pro.json", 40, 300, 0.5, "sneak"))
 table.insert(skeletons, loadSkeleton("coin.atlas", "coin-pro.json", 240, 160, 0.4, "animation"))
 table.insert(skeletons, loadSkeleton("raptor.atlas", "raptor-pro.json", 200, 300, 0.25, "walk"))

spine-lua/SkeletonClipping.lua

@@ -34,6 +34,7 @@ local Triangulator = require "spine-lua.Triangulator"
 local setmetatable = setmetatable
 local math_min = math.min
 local math_max = math.max
+local math_abs = math.abs
 local ipairs = ipairs
 local table_insert = table.insert
 local table_remove = table.remove
@@ -256,16 +257,28 @@ function SkeletonClipping:clip(x1, y1, x2, y2, x3, y3, clippingArea, output)
 					-- v1 inside, v2 outside
 					local c0 = inputY2 - inputY
 					local c2 = inputX2 - inputX
-					local ua = (c2 * (edgeY - inputY) - c0 * (edgeX - inputX)) / (c0 * (edgeX2 - edgeX) - c2 * (edgeY2 - edgeY))
-					table_insert(output, edgeX + (edgeX2 - edgeX) * ua)
-					table_insert(output, edgeY + (edgeY2 - edgeY) * ua)
+					local s = c0 * (edgeX2 - edgeX) - c2 * (edgeY2 - edgeY)
+					if math_abs(s) > 0.000001 then
+						local ua = (c2 * (edgeY - inputY) - c0 * (edgeX - inputX)) / s
+						table_insert(output, edgeX + (edgeX2 - edgeX) * ua)
+						table_insert(output, edgeY + (edgeY2 - edgeY) * ua)
+					else
+						table_insert(output, edgeX)
+						table_insert(output, edgeY)
+					end
 				end
 			elseif side2 then -- v1 outside, v2 inside
 				local c0 = inputY2 - inputY
 				local c2 = inputX2 - inputX
-				local ua = (c2 * (edgeY - inputY) - c0 * (edgeX - inputX)) / (c0 * (edgeX2 - edgeX) - c2 * (edgeY2 - edgeY))
-				table_insert(output, edgeX + (edgeX2 - edgeX) * ua)
-				table_insert(output, edgeY + (edgeY2 - edgeY) * ua)
+				local s = c0 * (edgeX2 - edgeX) - c2 * (edgeY2 - edgeY)
+				if math_abs(s) > 0.000001 then
+					local ua = (c2 * (edgeY - inputY) - c0 * (edgeX - inputX)) / s
+					table_insert(output, edgeX + (edgeX2 - edgeX) * ua)
+					table_insert(output, edgeY + (edgeY2 - edgeY) * ua)
+				else
+					table_insert(output, edgeX)
+					table_insert(output, edgeY)
+				end
 				table_insert(output, inputX2)
 				table_insert(output, inputY2)
 			end