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| -rw-r--r-- | LICENSE.txt | 7 | ||||
| -rw-r--r-- | README.md | 57 | ||||
| -rw-r--r-- | fakecanvas.lua | 254 |
3 files changed, 318 insertions, 0 deletions
diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..0f60866 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,7 @@ +Copyright (C) 2012 Xgoff + +Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
\ No newline at end of file diff --git a/README.md b/README.md new file mode 100644 index 0000000..f819b10 --- /dev/null +++ b/README.md @@ -0,0 +1,57 @@ +##fakecanvas + +fakecanvas is an attempt at emulating the functionality of canvases (render to texture) for hardware that does not support them. + +it is more or less a drop-in library, in that all you need to do is call `require 'fakecanvas'` (preferably inside `love.load`) to use it. fakecanvas' own functions will only be used if `love.graphics.isSupported "canvas"` is false, unless this behavior is overridden (see below). + +it uses (a few) screenshots in order to isolate drawing operations, which means there are some amusing drawbacks: + +* it's slow +* possible drawing issues if you call `love.graphics.present()` yourself, specifically between `setCanvas()` calls +* canvas width/height cannot exceed the window's width/height, and if your hardware lacks PO2 support, canvases will be further limited to that as well. ie: for an 800x600 display the max canvas size is 512x512. 1024x768 will limit you to 1024x512, and so on. +* any other weirdness you might run across + +not to mention: + +* it's apparently impossible to seamlessly impersonate real canvases, so functions that involve canvases (specifically those that need the image data) need to be wrapped. some of these have probably been missed. +* it uses the debug library, which may or may not be available +* the above is used to poke around LÖVE's internals (currently, to wrap pixeleffects' `send()` method) which is especially dodgy +* ??? + +beware: i have done only minimal testing of this library so it's possible there are cases where it doesn't work correctly or at all, or that the entire idea is ultimately unworkable! + +so, consider this more of a proof-of-concept than as an actual alternative. get better drivers/hardware dammit >:( + +###API + +fakecanvas directly replaces some of LÖVE's functions, so there are no special functions you need to use. however, the library itself consists of a couple extra functions: + +* `enable([state])`: control fakecanvas' usage directly by passing the `state` argument, which can be one of: + * `true`: force usage of fakecanvas' functions even if real canvases are supported + * `false`: disable canvas functions even if real canvases are supported + * `nil` (or no argument): **default**. fakecanvas will only use its own functions if real canvases are not supported + +* `getMaxCanvasSize([hint_w, hint_h])`: returns the maximum size fakecanvas can use for fake canvases. real canvases can likely be made much larger, so this can be used to put an upper limit on their size if needed. for convenience, you can provide width and height hints to this function, which will be clamped if they exceed the maximum size, or returned unmodified if they don't. + +### Example main.lua + +```lua +local c +function love.load () + local fc = require 'fakecanvas' + + c = love.graphics.newCanvas(fc.getMaxCanvasSize(256, 256)) + + c:renderTo(function () + love.graphics.circle("fill", 128, 128, 96) + love.graphics.setColor(0, 0, 0, 255) + love.graphics.printf("did it work?", 0, 128, 256, "center") + love.graphics.setColor(255, 255, 255, 255) + end) + +end + +function love.draw () + love.graphics.draw (c, 0, 0) +end +```
\ No newline at end of file diff --git a/fakecanvas.lua b/fakecanvas.lua new file mode 100644 index 0000000..bc2e457 --- /dev/null +++ b/fakecanvas.lua @@ -0,0 +1,254 @@ +assert(debug, "fake canvases require access to the debug library") + +local canvas_supported = love.graphics.isSupported "canvas" +local npot_supported = love.graphics.isSupported "npot" +local pixeleffect_supported = love.graphics.isSupported "pixeleffect" + +local function nextpo2 (x) return 2^math.ceil(math.log(x) / math.log(2)) end +local function prevpo2 (x) return 2^math.floor(math.log(x) / math.log(2)) end + +local _types = { "Canvas" == true, "Object" == true, "Drawable" == true } +local canvas = { } +local canvasmt = { __index = canvas } + +local canvases = setmetatable({ }, { __mode = "k" }) + +function canvas:clear (...) -- other option is chucking out the imagedata and creating a new one, but i'd probably end up using mapPixel anyway + local nargs = select("#", ...) + + if nargs == 0 then + canvases[self]._imagedata:mapPixel(function () return 0, 0, 0, 0 end) + elseif nargs == 1 and type(...) == "table" then + local t = ... + local r, g, b, a = tonumber(t[1]) or 0, tonumber(t[2]) or 0, tonumber(t[3]) or 0, tonumber(t[4]) or 255 + canvases[self]._imagedata:mapPixel(function () return r, g, b, a end) + else + local r, g, b, a = ... + r, g, b, a = tonumber(r) or 0, tonumber(g) or 0, tonumber(b) or 0, tonumber(a) or 255 + canvases[self]._imagedata:mapPixel(function () return r, g, b, a end) + end +end + +function canvas:getFilter () + return canvases[self]._image:getFilter() +end + +function canvas:getImageData () + return canvases[self]._imagedata +end + +function canvas:getWrap () + return canvases[self]._image:getWrap() +end + +function canvas:renderTo (renderfunc) + love.graphics.setCanvas(self) + renderfunc() + love.graphics.setCanvas() +end + +function canvas:setFilter (min, mag) + canvases[self]._image:setFilter(min, mag) +end + +function canvas:setWrap (h, v) + canvases[self]._image:setWrap(h, v) +end + +function canvas:type () + return "Canvas" +end + +function canvas:typeOf (type) + return _types[type] +end + +-- internal +function canvas:_getImage () + return canvases[self]._image +end + +function canvas:_getQuad () + return canvases[self]._quad +end + +local function Canvas (width, height) + local c = { } + + local sw, sh = love.graphics.getWidth(), love.graphics.getHeight() + + local w, h + if npot_supported then -- awesome, just limit to screen size + w = math.min(sw, tonumber(width) or sw) + h = math.min(sh, tonumber(height) or sh) + else -- well that sucks + w = math.min(prevpo2(sw), nextpo2(tonumber(width) or 1)) + h = math.min(prevpo2(sh), nextpo2(tonumber(height) or 1)) + end + + c._imagedata = love.image.newImageData(w, h) + c._image = love.graphics.newImage(c._imagedata) + c._quad = love.graphics.newQuad(0, 0, w, h, w, h) + + c._quad:flip(false, true) -- flip vertically part 0 + + local p = newproxy(true) + + canvases[p] = c + + getmetatable(p).__index = canvasmt.__index + + return p --setmetatable(p, canvasmt) +end + +local current_canvas +local function getCanvas () + return current_canvas +end + +local _fb_state +local function savefbstate () + _fb_state = { + color = { love.graphics.getBackgroundColor() }, + data = love.graphics.newScreenshot(), + scissor = { love.graphics.getScissor() }, + } + _fb_state.image = love.graphics.newImage(_fb_state.data) + --_fb_state.data:encode("__fb.png") +end + +savefbstate() + +local function setCanvas (...) + assert(select("#", ...) == 0 or (select("#", ...) == 1 and type(...) == "userdata"), "Incorrect parameter type: expected userdata") + local to = ... + if to then + current_canvas = canvases[to] + --print "saving background state" + savefbstate() + + --print "rendering setup" + love.graphics.setScissor() + love.graphics.setBackgroundColor(0, 0, 0, 0) + love.graphics.clear() + else + --print "saving to canvas" + local tempdata = love.graphics.newScreenshot() + + love.graphics.setBackgroundColor(0, 0, 0, 0) + love.graphics.clear() + + -- flip vertically (unfortunately) so it can later be drawn unflipped in order to match texcoords of real canvases. part 1 + local flipped = love.graphics.newImage(tempdata) + love.graphics.draw(flipped, 0, current_canvas._imagedata:getHeight(), 0, 1, -1) + + local newdata = love.graphics.newScreenshot() + + --newdata:encode("__canvas.png") + + current_canvas._imagedata:paste(newdata, 0, 0, 0, 0, current_canvas._imagedata:getWidth(), current_canvas._imagedata:getHeight()) + current_canvas._image = love.graphics.newImage(current_canvas._imagedata) -- apparently images don't update when their imagedata changes, so + + --print "restoring background state" + love.graphics.setBackgroundColor(0, 0, 0, 0) + love.graphics.clear() + love.graphics.clear() + love.graphics.setScissor() + love.graphics.draw(_fb_state.image, 0, 0) + love.graphics.setBackgroundColor(unpack(_fb_state.color)) + love.graphics.setScissor(unpack(_fb_state.scissor)) + current_canvas = nil + end +end + +local registry = debug.getregistry() -- naughty! + + -- throwaway, forces LOVE to load the :send() method +love.graphics.newPixelEffect [[vec4 effect( vec4 x, Image y, vec2 z, vec2 w) { return vec4(0, 0, 0, 0); }]] + +local _love_funcs = { + getCanvas = love.graphics.getCanvas, + setCanvas = love.graphics.setCanvas, + newCanvas = love.graphics.newCanvas, + + draw = love.graphics.draw, + drawq = love.graphics.drawq, + + pe_send = registry.PixelEffect.send, + --technically sendCanvas should also be wrapped but that's not officially exposed +} +local _wrap_funcs = { + getCanvas = getCanvas, + setCanvas = setCanvas, + newCanvas = Canvas, + + draw = function (obj, x, y, r, sw, sh, ox, oy, kx, ky) + if canvases[obj] then + return _love_funcs.drawq(obj:_getImage(), obj:_getQuad(), x, y, r, sw, sh, ox, oy, kx, ky) -- flip texcoords part 2 + end + return _love_funcs.draw(obj, x, y, r, sw, sh, ox, oy, kx, ky) + end, + drawq = function (obj, x, y, r, sw, sh, ox, oy, kx, ky) + if canvases[obj] then + return _love_funcs.drawq(obj:_getImage(), x, y, r, sw, sh, ox, oy, kx, ky) + end + return _love_funcs.drawq(obj, x, y, r, sw, sh, ox, oy, kx, ky) + end, + + pe_send = function (pe, name, data) + if canvases[data] then + return _love_funcs.pe_send(pe, name, data:_getImage()) + end + return _love_funcs.pe_send(pe, name, data) + end, +} + +local M = { } + +-- enable use of fake canvases +-- state: +-- true: use fake canvases even if real ones are supported +-- false: disable canvases entirely +-- nil: use real or fake canvases based on support +function M.enable (state) + if state == true or not canvas_supported then + love.graphics.getCanvas = _wrap_funcs.getCanvas + love.graphics.setCanvas = _wrap_funcs.setCanvas + love.graphics.newCanvas = _wrap_funcs.newCanvas + love.graphics.draw = _wrap_funcs.draw + love.graphics.drawq = _wrap_funcs.drawq + + registry.PixelEffect.send = _wrap_funcs.pe_send + elseif state == false then + love.graphics.getCanvas = function () return nil end + love.graphics.setCanvas = function () end + love.graphics.newCanvas = function () error("canvases disabled", 2) end + + love.graphics.draw = _love_funcs.draw + love.graphics.drawq = _love_funcs.drawq + + registry.PixelEffect.send = _love_funcs.pe_send + elseif state == nil and canvas_supported then + love.graphics.getCanvas = _love_funcs.getCanvas + love.graphics.setCanvas = _love_funcs.setCanvas + love.graphics.newCanvas = _love_funcs.newCanvas + love.graphics.draw = _love_funcs.draw + love.graphics.drawq = _love_funcs.drawq + + registry.PixelEffect.send = _love_funcs.pe_send + end + return M +end + +function M.getMaxCanvasSize (hw, hh) + local w, h = love.graphics.getWidth(), love.graphics.getHeight() + if npot_supported then + return math.min(hw, w), math.min(hh, h) + else + return prevpo2(math.min(hw, w)), prevpo2(math.min(hh, h)) + end +end + +M.enable() + +return M
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