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GradientText.. Just for the Fun

edited April 2013 in Examples Posts: 68

--# GradientText GradientText = class() function GradientText:init(x,y,txt,color1,color2,size) self.x = x self.y = y self.txt = txt self.col1 = color1 self.col2 = color2 self.size = size end function GradientText:draw() fontSize(self.size) local x=0 local diffR, diffG, diffB = (self.col2.r - self.col1.r), (self.col2.g - self.col1.g), (self.col2.b - self.col1.b) local stepR, stepG, stepB = (diffR / #self.txt), (diffG / #self.txt), (diffB / #self.txt) for i = 1, #self.txt do fill(i * stepR + self.col1.r, i * stepG + self.col1.g, i * stepB + self.col1.b) text(string.sub(self.txt, i, i), self.x + x, self.y) x = x + textSize(string.sub(self.txt, i, i)) end end function GradientText:touched(touch) -- Codea does not automatically call this method end --# Main -- GradientText function setup() displayMode(FULLSCREEN) textMode(CORNER) text1 = GradientText(50, 200, "Hello world...", color(0, 255, 0), color(0, 0, 255), 30) text2 = GradientText(50, 300, "Bonjour le monde...", color(023, 234, 456), color(34, 67, 89), 60) text3 = GradientText(50, 450, "Very fuuuunnnn...", color(255, 255, 255), color(255, 0, 0), 120) end function draw() background() text1:draw() text2:draw() text3:draw() end function touched(touch) end


  • Posts: 1,595

    That's a pretty good start and even though it doesn't have too many applications I'm sure someone's gonna need it

  • Posts: 68

    yes it is really for fun..... =:)

  • Posts: 666

    seems like this would be better in a shader so that the GPU does the work.

  • Posts: 68

    @aciolino, This is a simple example, but if you want to optimize ...
    This class can be used as a member

  • Posts: 688

    Another way to potentially do this would be to draw the text in white into an image and then render the image as a mesh (using the image as a texture) and then set the vertex colours which could be animated to produce some funky text effects.

  • edited October 2014 Posts: 688

    Couldn't help myself, so I decided to code the above as a proof of concept demo (and threw in some shader love as well)

    -- Gradient Text
    -- A simnple proof of concept demo - enjoy
    local myString = "Codea Rocks!"
    local tSize = 100
    local txtImg, txtMesh, shaderMesh
    -- Use this function to perform your initial setup
    function setup()
        -- Setup the text style
        fontSize(tSize); textAlign(LEFT); textMode(CORNER);
        -- Create an image of the text
        txtImg = image(textSize(myString))
        fill(255); text(myString,0,0)
        -- Create a mesh with the image as a texture
        local w,h   = txtImg.width, txtImg.height
        local lx,ly = 50, 300
        local c1 = color(255,0,0)
        local c2 = color(0,255,0)
        local c3 = color(0,0,255)
        local c4 = color(255,255,0)
        -- Note - Meshes are made up of TRIANGLES!!!
        txtMesh = mesh()
        txtMesh.vertices  = { vec2(lx,ly),  vec2(lx+w,ly), vec2(lx+w,ly+h),
                              vec2(lx,ly),  vec2(lx+w,ly+h), vec2(lx,ly+h)}
        txtMesh.colors    = {c3,c3,c1, c3,c1,c1 }
        txtMesh.texture   = txtImg
        txtMesh.texCoords = { vec2(0,0), vec2(1,0), vec2(1,1),
                              vec2(0,0), vec2(1,1), vec2(0,1) }
        -- Duplicate the above but use a shader (just because!)
        shaderMesh = mesh()
        shaderMesh.vertices  = { vec2(lx,ly-100),  vec2(lx+w,ly-100), vec2(lx+w,ly+h-100),
                                 vec2(lx,ly-100),  vec2(lx+w,ly+h-100), vec2(lx,ly+h-100)}
        shaderMesh.colors    = {c3,c3,c1, c3,c1,c1 }
        shaderMesh.texture   = txtImg
        shaderMesh.texCoords = { vec2(0,0), vec2(1,0), vec2(1,1),
                                 vec2(0,0), vec2(1,1), vec2(0,1) }
        shaderMesh.shader = shader("Effects:Ripple")
    -- This function gets called once every frame
    function draw()
        -- This sets a dark background color 
        background(40, 40, 50)
        -- This sets the line thickness
        -- Do your drawing here
        -- Normal
        fontSize(tSize); textAlign(LEFT); textMode(CORNER)
        fill(255); text(myString,50,500)
        -- As an image
        -- As a mesh
        -- Also with a shader
        shaderMesh.shader.freq = 0.4
        shaderMesh.shader.time = ElapsedTime

    Enjoy :)

    NOTE - Remember meshes are lists of separate triangles, so that's why there are two sets of three - I did consider using the addRect() method but I wanted a bit more control, plus you can create a nice reflection effect on the shader text, by skewing out the bottom x coords and inverting the texture.


        -- Duplicate the above but use a shader (just because!)
        shaderMesh = mesh()
        shaderMesh.vertices  = { vec2(lx-80,ly-100),  vec2(lx+w+80,ly-100), vec2(lx+w,ly+h-100),
                                 vec2(lx-80,ly-100),  vec2(lx+w+80,ly+h-100), vec2(lx,ly+h-100)}
        shaderMesh.colors    = {c2,c2,c3, c2,c3,c3 }
        shaderMesh.texture   = txtImg
        shaderMesh.texCoords = { vec2(0,1), vec2(1,1), vec2(1,0),
                                 vec2(0,1), vec2(1,0), vec2(0,0) }
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