nullifier.lua

--nullifier.lua by Enjl
--makes it so a range of priorities is not drawn in certain locations, tied to a BGO ID
--Ver 1.0

local nullifier = {}

local registeredRanges = {}

--CHANGE THIS to change which BGO becomes a nullifier
nullifier.id = 1

local tableinsert = table.insert

local cb = Graphics.CaptureBuffer(800, 600)

--CALL THIS to add a range of priorities which the nullifier should skip over
function nullifier.addRange(min, max)
    if min > max then
        max, min = min, max
    end
    tableinsert(registeredRanges, {capturePriority = min, drawPriority = max})
end

function nullifier.onInitAPI()
    registerEvent(nullifier, "onCameraDraw")
    registerEvent(nullifier, "onStart")
end

function nullifier.onStart()
    if #BGO.get(nullifier.id) == 0 then
        unregisterEvent(nullifier, "onCameraDraw")
    end
end

local function insertVertices(t, x1, y1, x2, y2)
    tableinsert(t, x1)
    tableinsert(t, y1)
    tableinsert(t, x2)
    tableinsert(t, y1)
    tableinsert(t, x1)
    tableinsert(t, y2)
    tableinsert(t, x2)
    tableinsert(t, y1)
    tableinsert(t, x1)
    tableinsert(t, y2)
    tableinsert(t, x2)
    tableinsert(t, y2)
end

function nullifier.onCameraDraw(camIdx)
    local verts = {}
    local tex = {}

    local cam = Camera.get()[camIdx]

    local cx = cam.x
    local cy = cam.y
    local cw = cam.width
    local ch = cam.height

    for k,v in ipairs(BGO.getIntersecting(cx, cy, cx + cw, cy + ch)) do
        if v.id == nullifier.id and not v.isHidden then
            local x = v.x - cx
            local y = v.y - cy
            local xw = x + v.width
            local yh = y + v.height
            insertVertices(verts, x,y,xw,yh)
            insertVertices(tex, x/cw,y/ch,xw/cw,yh/ch)
        end
    end

    if #verts > 0 then
        for k,v in ipairs(registeredRanges) do
            cb:captureAt(v.capturePriority)
            Graphics.glDraw{
                vertexCoords = verts,
                textureCoords = tex,
                texture = cb,
                priority = v.drawPriority,
                primitive = Graphics.GL_TRIANGLES
            }
        end
    end
end

return nullifier