library-mirrors/light_world.lua
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big optimizations to the polygon shadow calculations

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This commit is contained in:
Tim Anema 2014-12-13 23:15:39 -05:00
parent fac5d932f2
commit 41058d5d5b
1 changed files with 23 additions and 32 deletions
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55
lib/body.lua
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@ -626,23 +626,13 @@ function body:drawShadow(light)
end
end
local function isEdgeFacingLight(x1, y1, x2, y2, light)
return vec2(-y2 + y1, x2 - x1):dot(vec2(x1 - light.x, y1 - light.y)) > 0
end
--using shadow point calculations from this article
--http://web.cs.wpi.edu/~matt/courses/cs563/talks/shadow/shadow.html
function body:drawPolyShadow(light)
local edgeFacingTo = {}
for k = 1, #self.data, 2 do
local indexOfNextVertex = (k + 2) % #self.data
local normal = vec2(-self.data[indexOfNextVertex+1] + self.data[k + 1], self.data[indexOfNextVertex] - self.data[k]):normalize()
local lightToPoint = vec2(self.data[k] - light.x, self.data[k + 1] - light.y):normalize()
local dotProduct = normal:dot(lightToPoint)
if dotProduct > 0 then
table.insert(edgeFacingTo, true)
else
table.insert(edgeFacingTo, false)
end
end
local curShadowGeometry = {}
local lxh = (light.x * self.zheight)
local lyh = (light.y * self.zheight)
@ -651,28 +641,29 @@ function body:drawPolyShadow(light)
height_diff = -0.001
end
for k = 1, #edgeFacingTo do
local nextIndex = (k + 1) % #edgeFacingTo
if nextIndex == 0 then nextIndex = #edgeFacingTo end
local facingLight = {}
for i = 1, #self.data, 2 do
local j, k = (i + 2) % #self.data, (i + 4) % #self.data
local x, y = self.data[nextIndex*2-1], self.data[nextIndex*2]
local xs, ys = (lxh - (x * light.z))/height_diff, (lyh - (y * light.z))/height_diff
facingLight[i] = facingLight[i] ~= nil and facingLight[i] or isEdgeFacingLight(self.data[i], self.data[i+1], self.data[j], self.data[j+1], light)
facingLight[j] = facingLight[j] ~= nil and facingLight[j] or isEdgeFacingLight(self.data[j], self.data[j+1], self.data[k], self.data[k+1], light)
if edgeFacingTo[k] and not edgeFacingTo[nextIndex] then
curShadowGeometry[#curShadowGeometry+1] = x
curShadowGeometry[#curShadowGeometry+1] = y
curShadowGeometry[#curShadowGeometry+1] = xs
curShadowGeometry[#curShadowGeometry+1] = ys
elseif not edgeFacingTo[k] and not edgeFacingTo[nextIndex] then
curShadowGeometry[#curShadowGeometry+1] = xs
curShadowGeometry[#curShadowGeometry+1] = ys
elseif not edgeFacingTo[k] and edgeFacingTo[nextIndex] then
curShadowGeometry[#curShadowGeometry+1] = xs
curShadowGeometry[#curShadowGeometry+1] = ys
curShadowGeometry[#curShadowGeometry+1] = x
curShadowGeometry[#curShadowGeometry+1] = y
if facingLight[i] and not facingLight[j] then
curShadowGeometry[#curShadowGeometry+1] = self.data[j]
curShadowGeometry[#curShadowGeometry+1] = self.data[j+1]
curShadowGeometry[#curShadowGeometry+1] = (lxh - (self.data[j] * light.z))/height_diff
curShadowGeometry[#curShadowGeometry+1] = (lyh - (self.data[j+1] * light.z))/height_diff
elseif not facingLight[i] and not facingLight[j] then
curShadowGeometry[#curShadowGeometry+1] = (lxh - (self.data[j] * light.z))/height_diff
curShadowGeometry[#curShadowGeometry+1] = (lyh - (self.data[j+1] * light.z))/height_diff
elseif not facingLight[i] and facingLight[j] then
curShadowGeometry[#curShadowGeometry+1] = (lxh - (self.data[j] * light.z))/height_diff
curShadowGeometry[#curShadowGeometry+1] = (lyh - (self.data[j+1] * light.z))/height_diff
curShadowGeometry[#curShadowGeometry+1] = self.data[j]
curShadowGeometry[#curShadowGeometry+1] = self.data[j+1]
end
end
if #curShadowGeometry >= 6 then
love.graphics.polygon("fill", unpack(curShadowGeometry))
end