Another use of RenderTarget

chuz0

Hello,
Besides the obvious use, it can also be used for buttons with odd shapes.
See the code below:

inicio = Core.class(Sprite)   function inicio:init() wi = application:getContentWidth() he = application:getContentHeight()   local source = Bitmap.new(Texture.new("US_map_blank.jpg", true)) -- blank map   local colormap = Bitmap.new(Texture.new("US_map_colors.jpg",true)) -- coloured map   rt = RenderTarget.new(wi,he) rt:draw(colormap) local bmp = Bitmap.new(rt) bmp:setPosition(0, 0) self:addChild(bmp)   self:addChild(source)   self:addEventListener(Event.MOUSE_UP, self.onMouseUp, self)   end   function inicio:onMouseUp(ev)   local col,alph = rt:getPixel(ev.x, ev.y)   if math.abs(col-tonumber(000000,16))<5 then print("California") end if math.abs(col-tonumber(111111,16))<5 then print("Arizona") end if math.abs(col-tonumber(222222,16))<5 then print("New Mexico") end if math.abs(col-tonumber(333333,16))<5 then print("Texas") end if math.abs(col-tonumber(444444,16))<5 then print("Louisiana") end if math.abs(col-tonumber(555555,16))<5 then print("Mississippi") end if math.abs(col-tonumber(666666,16))<5 then print("Alabama") end if math.abs(col-tonumber(777777,16))<5 then print("Florida") end   end

Since it's just a proof of concept, and the code can be improved, I've just used the most southern states.
Find attached the jpgs I've used.

Regards.

antix

@chuz0 Very cool use of RenderTarget

MikeHart

Indeed, I am always amazed for what you can use Gideros.

hgy29

Good use of new getPixel() API !

keszegh

@hgy29 and other developers, wouldn't it be possible to add getPixel() function to stage as well (without performance/memory price)? (e.g. stage could inherit rendertarget) this would simplify life a lot and seems to be a natural thing to have.

SinisterSoft

Don't forget that the stage actually isn't drawn until after the event, it also isn't actually a bitmap - it's a list of objects that are to be drawn.

It would be easier (I don't know if this will work, it might) for you to maybe clip a master sprite object to the area you want look at, then draw it to a rendertarget, then unclip the master sprite to draw to the stage at the end of the event. Then getPixel on the render target ?

keszegh

@SinisterSoft,
i imagined that perhaps the stage behaves similarly as a rendertarget under the hood, as from outside it looks like that - something you assign sprites to, then it is clipped and drawn somewhere in some memory (on screen in the case of the stage).

what you propose is completely workable, i will check the performance hit of it as i want to make a color-picker to my drawing app, which means that i need to get the pixel at each frame.

hgy29

@keszegh, yes the stage is a rendertarget under the hood, as far as OpenGL is concerned. So adding getPixels() and soon save(), will be quite easy to do.

keszegh

@hgy29, sounds perfect. what is save()? If saving to file, then that's awesome too.

hgy29

yes, save will be saving the rendertarget's content to a file, either in .png or .jpg

keszegh

in this case by +1 I mean (+1)^1000.

hgy29

Well mathematically 1^1000 still equals 1 :P

keszegh

surely that's why i needed the additional comment.
how much easier life would be if google came up with +1.1 or +2 instead of +1.

n1cke

Actually it's +1 only in Lua. In C it's 1001 :-)

SinisterSoft

The difference between rendertarget and stage is that rendertarget is rendered when you do the draw command (so you can process immediately), stage is rendered after the ENTER_FRAME event (so you have to process afterwards, at the beginning of the next enter_frame event).

keszegh

@SinisterSoft, i could live with this one-frame difference.

SinisterSoft

@Hgy29 What would be useful is a command to copy the previously drawn stage texture to a render target.

antix

Wow, finally the ability to easily make screen dumps, awesome!