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+-------------------------------------------------------------------------------
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+-- Spine Runtimes Software License v2.5
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+--
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+-- Copyright (c) 2013-2016, Esoteric Software
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+-- All rights reserved.
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+--
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+-- You are granted a perpetual, non-exclusive, non-sublicensable, and
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+-- non-transferable license to use, install, execute, and perform the Spine
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+-- Runtimes software and derivative works solely for personal or internal
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+-- use. Without the written permission of Esoteric Software (see Section 2 of
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+-- the Spine Software License Agreement), you may not (a) modify, translate,
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+-- adapt, or develop new applications using the Spine Runtimes or otherwise
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+-- create derivative works or improvements of the Spine Runtimes or (b) remove,
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+-- delete, alter, or obscure any trademarks or any copyright, trademark, patent,
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+-- or other intellectual property or proprietary rights notices on or in the
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+-- Software, including any copy thereof. Redistributions in binary or source
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+-- form must include this license and terms.
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+--
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+-- THIS SOFTWARE IS PROVIDED BY ESOTERIC SOFTWARE "AS IS" AND ANY EXPRESS OR
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+-- IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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+-- MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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+-- EVENT SHALL ESOTERIC SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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+-- SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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+-- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, BUSINESS INTERRUPTION, OR LOSS OF
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+-- USE, DATA, OR PROFITS) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
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+-- IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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+-- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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+-- POSSIBILITY OF SUCH DAMAGE.
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+-------------------------------------------------------------------------------
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+
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+local utils = require "spine-lua.utils"
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+
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+local setmetatable = setmetatable
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+local math_min = math.min
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+local math_max = math.max
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+local ipairs = ipairs
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+local table_insert = table.insert
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+local table_remove = table.remove
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+
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+local Triangulator = {}
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+Triangulator.__index = Triangulator
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+
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+function Triangulator.new ()
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+ local self = {
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+ convexPolygons = {},
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+ convexPolygonsIndices = {},
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+ indicesArray = {},
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+ isConcaveArray = {},
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+ triangles = {}
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+ }
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+ setmetatable(self, Triangulator)
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+
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+ return self
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+end
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+
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+function Triangulator:triangulate (verticesArray)
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+ local vertices = verticesArray
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+ local vertexCount = #verticesArray / 2
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+
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+ self.indicesArray = {}
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+ local indicesArray = self.indicesArray
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+ local indices = utils.setArraySize(indicesArray, vertexCount)
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+ local i = 0
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+ while i < vertexCount do
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+ indices[i] = i
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+ i = i + 1
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+ end
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+
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+ local isConcaveArray = self.isConcaveArray
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+ local isConcave = isConcaveArray
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+ i = 0
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+ while i < vertexCount do
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+ isConcave[i] = self:isConcave(i, vertexCount, vertices, indices)
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+ i = i + 1
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+ end
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+
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+ self.triangles = {}
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+ local triangles = self.triangles;
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+
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+ while vertexCount > 3 do
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+ -- Find ear tip.
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+ local previous = vertexCount - 1
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+ local i = 0
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+ local _next = 1
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+ while true do
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+ local goToHead = false
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+ local breakLoop = false
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+ if not isConcave[i] then
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+ local p1 = indices[previous] * 2 + 1
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+ local p2 = indices[i] * 2 + 1
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+ local p3 = indices[_next] * 2 + 1
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+ local p1x = vertices[p1]
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+ local p1y = vertices[p1 + 1]
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+ local p2x = vertices[p2]
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+ local p2y = vertices[p2 + 1]
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+ local p3x = vertices[p3]
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+ local p3y = vertices[p3 + 1]
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+ local ii = ((_next + 1) % vertexCount)
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+ while ii ~= previous do
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+ if isConcave[ii] then
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+ local v = indices[ii] * 2 + 1
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+ local vx = vertices[v]
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+ local vy = vertices[v + 1]
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+ if self:positiveArea(p3x, p3y, p1x, p1y, vx, vy) then
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+ if self:positiveArea(p1x, p1y, p2x, p2y, vx, vy) then
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+ if self:positiveArea(p2x, p2y, p3x, p3y, vx, vy) then
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+ goToHead = true
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+ break
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+ end
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+ end
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+ end
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+ end
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+ ii = (ii + 1) % vertexCount
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+ end
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+ if (not goToHead) then
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+ breakLoop = true
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+ break
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+ end
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+ end
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+
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+ if breakLoop then break end
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+
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+ if _next == 0 then
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+ repeat
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+ if not isConcave[i] then
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+ break;
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+ end
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+ i = i - 1
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+ until i == 0
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+ break
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+ end
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+
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+ previous = i
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+ i = _next
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+ _next = (_next + 1) % vertexCount
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+ end
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+
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+ -- Cut ear tip.
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+ table_insert(triangles, indices[(vertexCount + i - 1) % vertexCount] + 1)
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+ table_insert(triangles, indices[i] + 1)
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+ table_insert(triangles, indices[(i + 1) % vertexCount] + 1)
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+ if i == 0 then
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+ local ii = 1
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+ while ii <= #indicesArray do
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+ indicesArray[ii-1] = indicesArray[ii]
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+ isConcaveArray[ii-1] = isConcaveArray[ii]
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+ ii = ii + 1
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+ end
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+ else
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+ table_remove(indicesArray, i)
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+ table_remove(isConcaveArray, i)
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+ end
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+ vertexCount = vertexCount - 1
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+
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+ local previousIndex = (vertexCount + i - 1) % vertexCount
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+ local nextIndex = i
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+ if i == vertexCount then nextIndex = 0 end
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+ isConcave[previousIndex] = self:isConcave(previousIndex, vertexCount, vertices, indices)
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+ isConcave[nextIndex] = self:isConcave(nextIndex, vertexCount, vertices, indices)
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+ end
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+
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+ if vertexCount == 3 then
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+ table_insert(triangles, indices[2] + 1)
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+ table_insert(triangles, indices[0] + 1)
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+ table_insert(triangles, indices[1] + 1)
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+ end
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+
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+ return triangles
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+end
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+
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+function Triangulator:isConcave(index, vertexCount, vertices, indices)
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+ local previous = indices[(vertexCount + index - 1) % vertexCount] * 2 + 1;
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+ local current = indices[index] * 2 + 1;
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+ local _next = indices[(index + 1) % vertexCount] * 2 + 1;
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+ return not self:positiveArea(vertices[previous], vertices[previous + 1], vertices[current], vertices[current + 1], vertices[_next],vertices[_next + 1]);
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+end
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+
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+function Triangulator:positiveArea(p1x, p1y, p2x, p2y, p3x, p3y)
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+ return p1x * (p3y - p2y) + p2x * (p1y - p3y) + p3x * (p2y - p1y) >= 0
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+end
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+
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+function Triangulator:winding(p1x, p1y, p2x, p2y, p3x, p3y)
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+ local px = p2x - p1x
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+ local py = p2y - p1y
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+ if p3x * py - p3y * px + px * p1y - p1x * py >= 0 then
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+ return 1
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+ else
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+ return -1;
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+ end
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+end
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+
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+return Triangulator
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