tweening rects in a mesh?

Questions
1

My failed attempt. Currently, I get the error: error: [string “-- tween.lua…”]:130: attempt to index a nil value (local ‘initial’)

I took some look at other questions asked (i searched tween mesh) but… ahh, I didn’t really understand. Well, they set the vertices directly. Whereas I’m going more for an approach where I want to make a function that would do, like, mesh:setRect, but it would be mesh:tweenRect… anyway, im giving up and going to bed, since its late. Hopefully this is my last question for a while, im feeling like i ask too much. Yes, thank you guys for always helping me

-- Meshtween

-- Use this function to perform your initial setu
local width, height = WIDTH/9, WIDTH/9*1.4
function setup()
    print("Hello World!")
    test = mesh()
    for i = 1,4 do
        test:addRect(WIDTH/9*i, HEIGHT/2, width/2, height/2)
        test:setRectColor(i, 50*i, 200-i*50, 20*i)
    end
end

-- works with meshes made entirely of rectangles
-- assumes the width, height are same
-- target should have keys x, y 
function tween_rect(time, myMesh, index, target)
    local position = myMesh:buffer('position')
    local myTable = position:get()
    local temp = mesh() 
    temp:addRect(target.x, target.y, width/2, height/2)
    local target = temp:buffer('position')
    local targTable = target:get()
    table.move(targTable, 1, 6, 6 * index - 5)
    local t1, t2, x,y,z, x2,y2,z2 = myTable, targTable
    local sub, tar = {},{}
    for i = index * 6 - 5, index * 6 do
        x,y,z = t1[i].x, t1[i].y, t1[i].z  --do x,y,z because tween wont work with vec3 object
        x2,y2,z2 = t2[i].x, t2[1].y, t2[i].z
        sub[i] = {x=x,y=y,z=z}
        tar[i] = {x=x2,y=y2,z=z2}
        tween(time, sub, tar)
        t1[i] = vec3(sub[i].x, sub[i].y, sub[i].z)
        --t2[i] = vec3(tar[i].x, tar[i].y, tar[i].z)
    end
    position:set(myTable)
end

-- This function gets called once every frame
function draw()
    -- This sets a dark background color 
    background(40, 40, 50)
    test:draw()
    tween_rect(1, test, 1, {x=1000, y=700})
    -- This sets the line thickness
    strokeWidth(5)

    -- Do your drawing here
    
end
2

Don’t be afraid to ask questions—people who ask more learn more.

  1. Tweening should only occur once only; calling tween repeatedly causes glitching.
  2. This version works by calling setRect on easing
function tween_rect(time, m, i, x,y)
    local current = {}
    local rx, ry
    for index = i, i + 6 do
        rx = (rx or 0) + m:vertex(index).x
        ry = (ry or 0) + m:vertex(index).y
    end
    rx = (m:vertex(i+1).x + m:vertex(i+2).x)/2 -- average
    ry = (m:vertex(i+4).y + m:vertex(i+6).y)/2
    -- rx and ry are center coords
    
    current.x = rx
    current.y = ry
    current.width = m:vertex(i+2).x - m:vertex(i+1).x
    current.height = m:vertex(i).y - m:vertex(i+1).y
    
    tween(1,current,{x=x,y=y},function(a,b,c,d) -- tween w/ custom easing function
        m:setRect(i,current.x,current.y,current.width,current.height) -- set every time
        return tween.easing.quadInOut(a,b,c,d) -- custom easing (set here)
    end)
end
3

My method includes hacking the tween easing functions. Run:

print(debug.getinfo(tween.start)["source"])
4

@xThomas I would give you some help, but I’m unsure what your objective is. Looking at your code doesn’t help me, but the discussion title gives me the idea that you want to create a mesh containing a rect and you want to do something with it using a tween. If that’s the case, what do you want the rect to do. If I’m wrong, could you explain what you want to do. I currently have a class that takes the 6 vertices of a mesh rectangle and moves the 4 corners around using 4 tweens. It basically stretches and squashes (distorts) the mesh image.