Irregular polygon with image texture

Code Sharing
1

@UberGoober Here’s another try. This creates a textured mesh. Tap the screen in either a clockwise or counter clockwise direction, a triangulate requirement. Nothing will happen until the third tap. After that a texture will show on the mesh as you keep tapping the screen.

I might be able to create a version that doesn’t use triangulate, so you can tap just about anywhere.

viewer.mode=FULLSCREEN

function setup()
    xmin,xmax,ymin,ymax=9999,0,999,0
    tab={}
    img=readImage(asset.builtin.Surfaces.Basic_Bricks_AO)
    m=mesh()
    m.texture=img  
    fill(255)
end

function draw()
    background(0)
    m.draw(m)
end

function touched(t)
    if t.state==BEGAN then
        calcCoords(t.x,t.y)
    end
end

function calcCoords(tx,ty)
    table.insert(tab,vec2(tx,ty))
    if tx<xmin then xmin=tx end
    if tx>xmax then xmax=tx end
    if ty<ymin then ymin=ty end
    if ty>ymax then ymax=ty end
    if #tab<3 then return end
    xwid,yhei=xmax-xmin,ymax-ymin
    tab1=triangulate(tab)
    texTab={}
    for a,b in pairs(tab1) do
        table.insert(texTab,vec2((b.x-xmin)/xwid,(b.y-ymin)/yhei))
    end  
    m.texCoords=texTab
    m.vertices=tab1 
end
2

Here’s another example that doesn’t use the triangulate function. After creating the first triangle, tap on two of the circles. They will be hi lighted and used as two points of a new triangle. Place the third point where ever to complete the triangle. Continue to create adjacent triangles. This doesn’t do anything other than create the image in the mesh polygon.

viewer.mode=FULLSCREEN

function setup()
    xmin,xmax,ymin,ymax=9999,0,999,0
    tab={}
    img=readImage(asset.builtin.Surfaces.Basic_Bricks_AO)
    m=mesh()
    m.texture=img  
    d1,d2=vec2(0,0),vec2(0,0)
end

function draw()
    background(40, 40, 50)
    fill(255)
    m.draw(m)
    if d1.x>0 then
        ellipse(d1.x,d1.y,30)
    end
    if d2.x>0 then
        ellipse(d2.x,d2.y,30)
    end
    fill(255,0,0)
    for a,b in pairs(tab) do
        ellipse(b.x,b.y,10)
    end
end

function touched(t)
    if t.state==BEGAN then
        if #tab>2 then 
            if d1.x>0 and d2.x>0 then
                table.insert(tab,vec2(t.x,t.y))
                table.insert(tab,d1)
                table.insert(tab,d2)
                d1,d2=vec2(0,0),vec2(0,0)
                calcCoords()
            else
                close2(t.x,t.y) 
            end
        else
            table.insert(tab,vec2(t.x,t.y))
            calcCoords()
        end
    end
end

function close2(x,y) 
    v1=vec2(x,y)
    for a,b in pairs(tab) do
        v2=vec2(b.x,b.y)
        d=v1:dist(v2)
        if d<20 then
            if d1.x==0 then
                d1=v2
            elseif d2.x==0 then
                d2=v2
            end  
            return          
        end
    end
end

function calcCoords()
    for a,b in pairs(tab) do
        if b.x<xmin then xmin=b.x end
        if b.x>xmax then xmax=b.x end
        if b.y<ymin then ymin=b.y end
        if b.y>ymax then ymax=b.y end
    end
    if #tab<3 then return end
    xwid,yhei=xmax-xmin,ymax-ymin
    texTab={}
    for a,b in pairs(tab) do
        table.insert(texTab,vec2((b.x-xmin)/xwid,(b.y-ymin)/yhei))
    end  
    m.texCoords=texTab
    m.vertices=tab 
end
3

I don’t know if this will be useful, but you can create mesh triangles not connected to each other. The same image is spread over all the triangles.

viewer.mode=FULLSCREEN

function setup()
    xmin,xmax,ymin,ymax=9999,0,9999,0
    tab={}
    img=readImage(asset.builtin.Surfaces.Basic_Bricks_AO)
    m=mesh()
    m.texture=img  
    d1,d2=vec2(0,0),vec2(0,0)
end

function draw()
    background(40, 40, 50)
    fill(255)
    m.draw(m)
    for a,b in pairs(tab) do
        ellipse(b.x,b.y,10)
    end
end

function touched(t)
    if t.state==BEGAN then
        table.insert(tab,vec2(t.x,t.y))
        calcCoords()
    end
end

function calcCoords()
    for a,b in pairs(tab) do
        if b.x<xmin then xmin=b.x end
        if b.x>xmax then xmax=b.x end
        if b.y<ymin then ymin=b.y end
        if b.y>ymax then ymax=b.y end
    end
    xwid,yhei=xmax-xmin,ymax-ymin
    texTab={}
    for a,b in pairs(tab) do
        table.insert(texTab,vec2((b.x-xmin)/xwid,(b.y-ymin)/yhei))
    end  
    m.texCoords=texTab
    m.vertices=tab 
end
4

These are great @dave1707, thanks so much! I’m curious why you wanted to remove triangulation—it seems to me like the first one you posted works the best.

5

@UberGoober With triangulation, you have to go in a clockwise or counterclockwise direction and your limited to where to create the triangles. I like the last one the best because I can create triangles anywhere, even across other triangles.

6

@dave1707 Great examples - many thanks for taking the time to put these together.