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Viewing changes to zoetrope/sprites/map.lua

Committer: Josh C
Date: 2013-03-05 00:14:58 UTC
Revision ID: josh@9ix.org-20130305001458-206jxv29dgeenj3n

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zoetrope/sprites/map.lua

-- set bounds

self.width = #self.map * self.spriteWidth

self.height = #self.map[1] * self.spriteHeight

self.width = #self.map[1] * self.spriteWidth

self.height = #self.map * self.spriteHeight

return self

end,

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return self

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end,

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-- Method: subcollide

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-- This acts as a wrapper to multiple collide() calls, as if

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-- there really were all the sprites in their particular positions.

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-- This is much more useful than Map:collide(), which simply checks

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-- if a sprite or group is touching the map at all.

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-- Arguments:

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-- other - other <Sprite> or <Group>

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-- Returns:

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-- boolean, whether any collision was detected

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subcollide = function (self, other)

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local hit = false

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local others

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if other.sprites then

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others = other.sprites

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else

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others = { other }

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end

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for _, othSpr in pairs(others) do

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if othSpr.solid then

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if othSpr.sprites then

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-- recurse into subgroups

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-- order is important here to avoid short-circuiting inappopriately

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hit = self:subcollide(othSpr.sprites) or hit

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else

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local startX, startY = self:pixelToMap(othSpr.x - self.x, othSpr.y - self.y)

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local endX, endY = self:pixelToMap(othSpr.x + othSpr.width - self.x,

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othSpr.y + othSpr.height - self.y)

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local x, y

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for x = startX, endX do

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for y = startY, endY do

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local spr = self.sprites[self.map[x][y]]

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if spr and spr.solid then

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-- position our map sprite as if it were onscreen

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spr.x = self.x + (x - 1) * self.spriteWidth

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spr.y = self.y + (y - 1) * self.spriteHeight

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hit = spr:collide(othSpr) or hit

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end

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end

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end

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end

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end

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end

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return hit

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end,

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-- Method: subdisplace

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-- This acts as a wrapper to multiple displace() calls, as if

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-- there really were all the sprites in their particular positions.

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-- This is much more useful than Map:displace(), which pushes a sprite or group

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-- so that it does not touch the map in its entirety.

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-- Arguments:

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-- other - other <Sprite> or <Group> to displace

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-- xHint - force horizontal displacement in one direction, uses direction constants

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-- yHint - force vertical displacement in one direction, uses direction constants

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-- Returns:

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-- nothing

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subdisplace = function (self, other, xHint, yHint)

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local others

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if other.sprites then

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others = other.sprites

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else

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others = { other }

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end

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for _, othSpr in pairs(others) do

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if othSpr.solid then

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if othSpr.sprites then

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-- recurse into subgroups

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-- order is important here to avoid short-circuiting inappopriately

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self:subdisplace(othSpr.sprites)

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else

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-- determine sprites we might intersect with

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local startX, startY = self:pixelToMap(othSpr.x - self.x, othSpr.y - self.y)

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local endX, endY = self:pixelToMap(othSpr.x + othSpr.width - self.x,

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othSpr.y + othSpr.height - self.y)

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local hit = true

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local loops = 0

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-- We displace the target sprite along the axis that would satisfy the

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-- most map sprites, but at the minimum distance for all of them.

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-- xVotes and yVotes track which axis should be used; this is a

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-- proportional vote, with sprites that have large amounts of overlap

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-- getting more of a chance to overrule the others. We run this loop

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-- repeatedly to make sure we end up with the target sprite not overlapping

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-- anything in the map.

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-- This is based on the technique described at:

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-- http://go.colorize.net/xna/2d_collision_response_xna/

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while hit and loops < 3 do

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hit = false

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loops = loops + 1

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local xVotes, yVotes = 0, 0

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local minChangeX, minChangeY, absMinChangeX, absMinChangeY

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local origX, origY = othSpr.x, othSpr.y

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for x = startX, endX do

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for y = startY, endY do

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local spr = self.sprites[self.map[x][y]]

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if spr and spr.solid then

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-- position our map sprite as if it were onscreen

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spr.x = self.x + (x - 1) * self.spriteWidth

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spr.y = self.y + (y - 1) * self.spriteHeight

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-- displace and check to see if this displacement

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-- would result in a smaller shift than any so far

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spr:displace(othSpr)

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local xChange = othSpr.x - origX

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local yChange = othSpr.y - origY

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if xChange ~= 0 then

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xVotes = xVotes + math.abs(xChange)

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hit = true

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if not minChangeX or math.abs(xChange) < absMinChangeX then

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minChangeX = xChange

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absMinChangeX = math.abs(xChange)

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end

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end

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if yChange ~= 0 then

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yVotes = yVotes + math.abs(yChange)

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hit = true

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if not minChangeY or math.abs(yChange) < absMinChangeY then

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minChangeY = yChange

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absMinChangeY = math.abs(yChange)

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end

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end

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-- restore sprite to original position

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othSpr.x = origX

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othSpr.y = origY

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end

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end

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end

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if hit then

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if xVotes > 0 and xVotes > yVotes then

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othSpr.x = othSpr.x + minChangeX

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elseif yVotes > 0 then

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othSpr.y = othSpr.y + minChangeY

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end

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end

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end

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end

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end

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end

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end,

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-- Method: getMapSize

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-- Returns the size of the map in map coordinates.

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-- Returns the size of the map in sprites.

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-- Arguments:

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-- none

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end

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end,

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-- Method: pixelToMap

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-- Converts pixels to map coordinates.

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-- Arguments:

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-- x - x coordinate in pixels

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-- y - y coordinate in pixels

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-- clamp - clamp to map bounds? defaults to true

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-- Returns:

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-- x, y map coordinates

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pixelToMap = function (self, x, y, clamp)

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if type(clamp) == 'nil' then clamp = true end

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-- remember, Lua tables start at index 1

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local mapX = math.floor(x / self.spriteWidth) + 1

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local mapY = math.floor(y / self.spriteHeight) + 1

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-- clamp to map bounds

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if clamp then

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if mapX < 1 then mapX = 1 end

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if mapY < 1 then mapY = 1 end

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if mapX > #self.map then mapX = #self.map end

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if mapY > #self.map[1] then mapY = #self.map[1] end

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end

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return mapX, mapY

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end,

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-- Method: spriteAtMap

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-- Returns the sprite at a given set of map coordinates, with

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-- the correct pixel position for that sprite. Remember that

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-- sprites in maps are shared, so any changes you make to one

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-- sprite will carry over to all instances of that sprite in the map.

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-- Arguments:

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-- x - x coordinate in map units

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-- y - y coordinate in map units

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-- Returns:

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-- <Sprite> instance. If no sprite is present at these

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-- coordinates, the method returns nil.

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spriteAtMap = function (self, x, y)

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if self.map[x] and self.map[x][y] then

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local spr = self.sprites[self.map[x][y]]

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if spr then

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spr.x = (x - 1) * self.spriteWidth

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spr.y = (y - 1) * self.spriteHeight

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return spr

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end

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elseif STRICT then

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print('Warning: asked for map sprite at ' .. x .. ', ' .. y ' but map isn\'t that big')

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end

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end,

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-- Method: spriteAtPixel

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-- Returns the sprite at a given set of pixel coordinates, with

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-- the correct pixel position for that sprite. Remember that

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-- sprites in maps are shared, so any changes you make to one

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-- sprite will carry over to all instances of that sprite in the map.

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-- Arguments:

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-- x - x coordinate in pixels

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-- y - y coordinate in pixels

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-- Returns:

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-- <Sprite> instance. If no sprite is present at these

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-- coordinates, the method returns nil.

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spriteAtPixel = function (self, x, y)

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return self:spriteAtMap((x - 1) * self.spriteWidth, (y - 1) * self.spriteHeight)

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end,

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-- This overrides a method in <Sprite>, passing along

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-- collidedWith() calls to all sprites in the map touching a

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-- sprite.

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-- Arguments:

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-- other - other <Sprite>

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-- Returns:

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-- nothing

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collidedWith = function (self, other)

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local spriteWidth = self.spriteWidth

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local spriteHeight = self.spriteHeight

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local startX, startY = self:pixelToMap(other.x - self.x, other.y - self.y)

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local endX, endY = self:pixelToMap(other.x + other.width - self.x,

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other.y + other.height - self.y)

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-- collect collisions against sprites

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local collisions = {}

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for x = startX, endX do

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for y = startY, endY do

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local spr = self.sprites[self.map[x][y]]

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if spr and spr.solid then

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local sprX = self.x + (x - 1) * spriteWidth

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local sprY = self.y + (y - 1) * spriteHeight

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local xOverlap, yOverlap = other:overlap(sprX, sprY, spriteWidth, spriteHeight)

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if xOverlap ~= 0 or yOverlap ~= 0 then

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table.insert(collisions, { area = xOverlap * yOverlap, x = xOverlap, y = yOverlap,

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a = spr, ax = sprX, ay = sprY })

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end

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end

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end

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end

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-- sort as usual and pass off collidedWith() calls

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table.sort(collisions, Collision.sortCollisions)

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for _, col in ipairs(collisions) do

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col.a.x, col.a.y = col.ax, col.ay

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col.a:collidedWith(other, col.x, col.y)

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other:collidedWith(col.a, col.x, col.y)

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end

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end,

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-- this is here mainly for completeness; it's better to specify displacement

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-- in individual map sprites

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displace = function (self, other, xHint, yHint)

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if not self.solid or self == other or not other.solid then return end

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if STRICT then assert(other:instanceOf(Sprite), 'asked to displace a non-sprite') end

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local spriteWidth = self.spriteWidth

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local spriteHeight = self.spriteHeight

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local startX, startY = self:pixelToMap(other.x - self.x, other.y - self.y)

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local endX, endY = self:pixelToMap(other.x + other.width - self.x,

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other.y + other.height - self.y)

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-- collect collisions against sprites

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local collisions = {}

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for x = startX, endX do

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for y = startY, endY do

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local spr = self.sprites[self.map[x][y]]

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if spr and spr.solid then

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local sprX = self.x + (x - 1) * spriteWidth

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local sprY = self.y + (y - 1) * spriteHeight

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local xOverlap, yOverlap = other:overlap(sprX, sprY, spriteWidth, spriteHeight)

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if xOverlap ~= 0 or yOverlap ~= 0 then

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table.insert(collisions, { area = xOverlap * yOverlap, x = xOverlap, y = yOverlap,

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a = spr, ax = sprX, ay = sprY })

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end

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end

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end

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end

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-- sort as usual and displace

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table.sort(collisions, Collision.sortCollisions)

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for _, col in ipairs(collisions) do

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col.a.x, col.a.y = col.ax, col.ay

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col.a:displace(other)

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end

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end,

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draw = function (self, x, y)

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-- lock our x/y coordinates to integers

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-- to avoid gaps in the tiles

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sprite:draw(coords[1], coords[2])

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end

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end

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Sprite.draw(self)

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end,

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-- Method: pixelToMap

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-- Converts pixels to map coordinates.

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-- Arguments:

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-- x - x coordinate in pixels

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-- y - y coordinate in pixels

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-- clamp - clamp to map bounds? defaults to true

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-- Returns:

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-- x, y map coordinates

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pixelToMap = function (self, x, y, clamp)

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if type(clamp) == 'nil' then clamp = true end

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-- remember, Lua tables start at index 1

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local mapX = math.floor(x / self.spriteWidth) + 1

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local mapY = math.floor(y / self.spriteHeight) + 1

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-- clamp to map bounds

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if clamp then

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if mapX < 1 then mapX = 1 end

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if mapY < 1 then mapY = 1 end

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if mapX > #self.map then mapX = #self.map end

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if mapY > #self.map[1] then mapY = #self.map[1] end

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end

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return mapX, mapY

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end,

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-- makes sure all sprites receive startFrame messages

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