How to create a circle transition with transparency

Comments

• hgy29 Maintainer

  January 2017

  Hi @kermine,
  
  Your code doesn't work as you would expect because Gideros discards fully transparent pixels early in the rendering pipeline, so they don't get blended at all and screen isn't updated for those pixels.
  
  You can overcome this by redefining the shader program associated with your 'image', so that transparent pixels are no longer discarded.
  
  See my code below:

  local BasicTextureVShader= [[ attribute vec4 POSITION0; attribute vec2 TEXCOORD0;   uniform mat4 g_MVPMatrix;   varying mediump vec2 texCoord;   void main() { gl_Position = g_MVPMatrix * POSITION0; texCoord = TEXCOORD0; } ]]   local BasicTextureFShader=[[ uniform lowp sampler2D gTexture; varying mediump vec2 texCoord;   #ifdef GLES2 precision mediump float; #endif   void main() { gl_FragColor = texture2D(gTexture, texCoord); } ]]   local BasicTextureShaderAttrs= { {name="POSITION0",type=Shader.DFLOAT,mult=3,slot=0,offset=0}, {name="vColor",type=Shader.DUBYTE,mult=0,slot=1,offset=0}, {name="TEXCOORD0",type=Shader.DFLOAT,mult=2,slot=2,offset=0} }   local BasicTextureShaderConstants={ {name="g_MVPMatrix",type=Shader.CMATRIX,sys=Shader.SYS_WVP, vertex=true}, {name="gTexture",type=Shader.CTEXTURE,mult=1,vertex=false}, }     local BasicTextureShader= Shader.new( BasicTextureVShader,BasicTextureFShader, Shader.FLAG_FROM_CODE,BasicTextureShaderConstants,BasicTextureShaderAttrs)       application:setBackgroundColor(0xFF00FF)   local rt = RenderTarget.new(318, 417) local wrapper = Sprite.new() local image = Bitmap.new(Texture.new("image.png")) --local image = Bitmap.new(Texture.new("box.png"))   local mask = Bitmap.new(Texture.new("mask.png"))   mask:setAnchorPosition(300, 281) mask:setPosition(200, 200) mask:setScale(1.5)   image:setBlendMode(Sprite.MULTIPLY) image:setShader(BasicTextureShader)   wrapper:addChild(mask) wrapper:addChild(image)         wrapper:addEventListener(Event.ENTER_FRAME, function() rt:clear(0, 0) rt:draw(wrapper) end)   local bmp = Bitmap.new(rt) bmp:setPosition(500, 500)   stage:addChild(bmp) --stage:addChild(wrapper)   GTween.new(mask, 5, { scaleX = 0, scaleY = 0 }, { ease = easing.linear })

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