PlumDrawing

--Draws a line from x1,y1 to x2,y2 with given color, using name of wrapped AR controller
local function drawLineAR(wrapper,x1,y1,x2,y2,color)
    color = 0x000000 --Overriding color to black. Comment out to use custom colors
    local dx = x2 - x1
    local dy = y2 - y1
    local length = math.floor(math.sqrt((dx^2)+(dy^2)))
    for i = 1, length do
        local nextY = y1 + dy * (i / length)
        local nextX = x1 + dx * (i / length)
        wrapper.horizontalLine(nextX, nextX, nextY, color)
    end
end

--Draws an object with an indexList which points to a list x/y points, using name of wrapped AR controller
local function drawWireObj(wrapper,vL) --vL == vertice list. cL == color list
    local cL = vL.colorList
    for i = 1, #vL, 12 do --Draws a whole triangle per loop
        local i1,i2 = i+1, i+2
        local col = cL[(i+2)/3]
        drawLineAR(wrapper, vL[i],   vL[i+1], vL[i+4], vL[i+5], col) --vert 1 to 2
        drawLineAR(wrapper, vL[i+4], vL[i+5], vL[i+8], vL[i+9], col) --vert 2 to 3
        drawLineAR(wrapper, vL[i+8], vL[i+9], vL[i],   vL[i+1], col) --vert 3 to 1
    end
end

--Basically a line function with cutoffs for anything < 0.
local function drawFlatTriangle(wrapper,px1,px2,y,color)
    local xStart = math.ceil(px1 - 0.5)
    local xEnd =   math.ceil(px2 - 0.5)

    if xEnd > 0 then
        if xStart < 0 then xStart = 0 end
        for x = xStart, xEnd do
            wrapper.horizontalLine(x, x, y, color)
        end
    end
end

--Basically a line function with cutoffs for anything < 0.
local function drawFlatTriangleTerm(wrapper,px1,px2,y,color)
    local xStart = math.ceil(px1 - 0.5)
    local xEnd =   math.ceil(px2 - 0.5)

    if xEnd > 0 then
        if xStart < 0 then xStart = 0 end
        for x = xStart, xEnd do
            term.setCursorPos(x,y)
            term.write(" ")
        end
    end
end

--Both draw flat top and bottom draw an entire line at a time instead of each pixel individually b/c performance. Will add individual pixel support later.
local function drawFlatTopTriangle( wrapper,vec1,vec2,vec3,color )
    --Calculate slopes in screen space
    --Run over rise so we don't get infinite slopes
    local m1 = (vec3.x - vec1.x) / (vec3.y - vec1.y)
    local m2 = (vec3.x - vec2.x) / (vec3.y - vec2.y)

    --Calculate start and end scanlines
    local yStart = math.ceil(vec1.y - 0.5)
    local yEnd =   math.ceil(vec3.y - 0.5)-1 --the scanline AFTER the last line drawn, which is why it's offset by -1

    if yEnd > 0 then
        if yStart < 0 then yStart = 0 end
        for y = yStart, yEnd do
            --calculate start and end x's
            --Add 0.5 because we're calculating based on pixel centers
            local px1 = m1 * (y + 0.5 - vec1.y) + vec1.x
            local px2 = m2 * (y + 0.5 - vec2.y) + vec2.x

            drawFlatTriangleTerm( wrapper,px1,px2,y,color )
        end
    end
    term.setBackgroundColour(colors.black)
end

local function drawFlatBottomTriangle( wrapper,vec1,vec2,vec3,color )
    --Calculate slopes in screen space
    local m1 = (vec2.x - vec1.x) / (vec2.y - vec1.y)
    local m2 = (vec3.x - vec1.x) / (vec3.y - vec1.y)

    --Calculate start and end scanlines
    local yStart = math.ceil(vec1.y-0.5)
    local yEnd =   math.ceil(vec3.y-0.5)-1 --the scanline AFTER the last line drawn, which is why we need to subtract 1 otherwise we get visual bugs

    if yEnd > 0 then
        if yStart < 0 then yStart = 0 end
        for y = yStart, yEnd do
            --calculate start and end points (x/z coords)
            --Add 0.5 because we're calculating based on pixel centers
            local px1 = m1 * (y + 0.5 - vec1.y) + vec1.x
            local px2 = m2 * (y + 0.5 - vec1.y) + vec1.x

            drawFlatTriangleTerm( wrapper,px1,px2,y,color )
        end
    end
end

--Draws a solid triangle from 3 vectors
local function drawSolidTriangle( wrapper,pv1,pv2,pv3,color )
    --Sort vertices by y
    if pv2.y < pv1.y then pv1,pv2 = pv2,pv1 end
    if pv3.y < pv2.y then pv2,pv3 = pv3,pv2 end
    if pv2.y < pv1.y then pv1,pv2 = pv2,pv1 end

    if pv1.y == pv2.y then --Natural flat top
        --Sort top vertice by x
        if pv2.x < pv1.x then pv1,pv2 = pv2,pv1 end
        drawFlatTopTriangle(wrapper,pv1,pv2,pv3,color )
    elseif pv2.y == pv3.y then --Natural flat bottom
        --Sort bottom vertice by x
        if pv3.x < pv2.x then pv3,pv2 = pv2,pv3 end
        drawFlatBottomTriangle(wrapper,pv1,pv2,pv3,color )
    else --General triangle
        local alphaSplit  = (pv2.y-pv1.y)/(pv3.y-pv1.y)
        local zAlphaSplit = (pv2.z-pv1.z)/(pv3.z-pv1.z)
        local wAlphaSplit = (pv2.w-pv1.w)/(pv3.w-pv1.w) --maybe redundant
        local vi = {
            x = pv1.x + ((pv3.x - pv1.x) * alphaSplit),
            y = pv1.y + ((pv3.y - pv1.y) * alphaSplit),
            z = pv1.z + ((pv3.z - pv1.z) * zAlphaSplit),
            w = pv1.w + ((pv3.w - pv1.w) * wAlphaSplit)
        }
        if pv2.x < vi.x then --Major right
            drawFlatBottomTriangle(wrapper,pv1,pv2,vi,color)
            drawFlatTopTriangle(wrapper,pv2,vi,pv3,color)
        else --Major left
            drawFlatBottomTriangle(wrapper,pv1,vi,pv2,color)
            drawFlatTopTriangle(wrapper,vi,pv2,pv3,color)
        end
    end
end

--Draw an entire object one triangle at a time
--Converts points from the 1D table to vectors b/c I'm lazy and it's easier to process this way
local function drawSolidObj( wrapper, vL ) --vL == index List. cL == color list
    term.setBackgroundColour(colors.white)
    local cL = vL.colorList
        --OPTIMIZATION here?. Probably should convert to 1D at least for full optimization
    for i = 1, #vL, 12 do
        local v1 = vector.new( vL[i],   vL[i+1], vL[i+2]  )
        local v2 = vector.new( vL[i+4], vL[i+5], vL[i+6]  )
        local v3 = vector.new( vL[i+8], vL[i+9], vL[i+10] )
        v1.w = vL[i+3]
        v2.w = vL[i+7]
        v3.w = vL[i+11]
        drawSolidTriangle( wrapper, v1, v2, v3, cL[(i+2)/3] )
    end
    term.setBackgroundColour(colors.black)
end
-- + || 0, 1, 2, 3, || 4, 5, 6, 7, || 8, 9,  10, 11
-- = || 1, 2, 3, 4, || 5, 6, 7, 8, || 9, 10, 11, 12
-- K || x, y, z, w, || x, y, z, w, || x, y,  z,  w

--Expose functions
return
{
    drawWireObj = drawWireObj,
    drawSolidObj = drawSolidObj,
}