RenderTarget and shader demo

SinisterSoft

Here is an example of using RenderTarget and a shader to make a nice decay effect.

local width=application:getContentWidth() local height=application:getContentHeight()   local fakeScreen=RenderTarget.new(width,height,true) fakeScreen:clear(0x000000,1)   local playfield=Bitmap.new(fakeScreen) stage:addChild(playfield)   local decayV=[[ attribute highp vec3 vVertex; attribute mediump vec2 vTexCoord; uniform highp mat4 vMatrix; varying mediump vec2 fTexCoord;   void main() { vec4 vertex = vec4(vVertex,1.0); gl_Position = vMatrix*vertex; fTexCoord=vTexCoord; } ]]   local decayF=[[ uniform lowp vec4 fColor; uniform lowp sampler2D fTexture; varying mediump vec2 fTexCoord;   void main() { lowp vec4 pixel=fColor*texture2D(fTexture, fTexCoord); if (pixel.a==0.0) discard; pixel=floor(pixel*255.0*0.99)*0.0039; pixel.a=1.0; gl_FragColor = pixel; } ]]   local shader=Shader.new(decayV,decayF,Shader.FLAG_FROM_CODE, { {name="vMatrix",type=Shader.CMATRIX,sys=Shader.SYS_WVP,vertex=true}, {name="fColor",type=Shader.CFLOAT4,sys=Shader.SYS_COLOR,vertex=false}, {name="fTexture",type=Shader.CTEXTURE,vertex=false}, }, { {name="vVertex",type=Shader.DFLOAT,mult=3,slot=0,offset=0}, {name="vColor",type=Shader.DUBYTE,mult=4,slot=1,offset=0}, {name="vTexCoord",type=Shader.DFLOAT,mult=2,slot=2,offset=0}, });   local oldScreen=Bitmap.new(fakeScreen) oldScreen:setShader(shader)   local fakeStage=Sprite.new() fakeStage:addChild(oldScreen)   local lines={} for loop=1,10 do local line={} local r=math.random(50,255) local g=math.random(50,255) local b=math.random(50,255) line.sprite=Pixel.new((r*0x10000)+(g*0x100)+b,1,200,6) line.sprite:setAnchorPosition(100,3) fakeStage:addChild(line.sprite)   line.x=math.random(width) line.y=math.random(height) line.dir=math.random(360) line.speed=(math.random(10)/10)+4 line.rotation=0 lines[loop]=line end   function gameLoop(e) for loop=1,#lines do local line=lines[loop] line.rotation=line.rotation+line.dir/200 local nx=line.x+(math.sin(math.rad(line.dir))*line.speed) if nx<0 or nx>width then line.dir=360-line.dir else line.x=nx end local ny=line.y+(math.cos(math.rad(line.dir))*line.speed) if ny<0 or ny>height then line.dir=180-line.dir else line.y=ny end   line.sprite:setRotation(line.rotation) line.sprite:setPosition(line.x,line.y) end   fakeScreen:draw(fakeStage) end   stage:addEventListener(Event.ENTER_FRAME,gameLoop)

Thanks to help from @hgy29 for the shader code.

SinisterSoft

Updated slightly to work on mobiles.