-- current render target and camera

local rendertarget = octane.render.getRenderTargetNode()
local camera = rendertarget:getInputNode(octane.P_CAMERA)

-- camera transform

local pos = camera:getPinValue(octane.P_POSITION)
local target = camera:getPinValue(octane.P_TARGET)
local up = octane.vec.normalized(camera:getPinValue(octane.P_UP))

local Z = octane.vec.normalized(octane.vec.sub(target, pos))
local X = octane.vec.normalized(octane.vec.cross(up, Z))
local Y = octane.vec.normalized(octane.vec.cross(Z, X))

matrix = {
 {X[1], Y[1], Z[1], pos[1]},
 {X[2], Y[2], Z[2], pos[2]},
 {X[3], Y[3], Z[3], pos[3]},
}

-- field of view, lens shift and resolution

local fov = camera:getPinValue(octane.P_FOV)
local shift = camera:getPinValue(octane.P_LENS_SHIFT)
local resolution = rendertarget:getPinValue(octane.P_RESOLUTION)

local w = 2 * math.tan(math.rad(fov / 2))
local h = w * resolution[2] / resolution[1]

local matrix = octane.matrix.mul(matrix, octane.matrix.makeScale{-w, h, 1})

local uvmatrix = octane.matrix.makeTranslation{-.5 + shift[1], -.5 + shift[2], 0}

-- get selected texture or material node, and apply transform

function project(tex)
    proj = octane.node.create{
        type = octane.NT_PROJ_PERSPECTIVE,
        pinOwnerNode = tex,
        pinOwnerId   = octane.P_PROJECTION,
    }
    
    octane.node.create{
        type = octane.NT_TRANSFORM_VALUE,
        pinOwnerNode = tex,
        pinOwnerId   = octane.P_TRANSFORM,
    }

    tex:setPinValue(octane.P_TRANSFORM, uvmatrix)
    proj:setPinValue(octane.P_TRANSFORM, matrix)
end

-- node.getPinInfo raises an error when the pin doesn't exist.
function hasPin(n, pin)
    local r = pcall(n.getPinInfo, n, pin)
    return r
end

function hasProjection(n)
    return hasPin(n, octane.P_PROJECTION) and hasPin(n, octane.P_TRANSFORM)
end

local foundtex = false
for _, n in ipairs(octane.project.getSelection()) do
    if hasProjection(n) then
        foundtex = true
        project(n)
    elseif n:getProperties().outputType == octane.PT_MATERIAL then
        for i = 1, n:getPinCount() do
            local m = nil
            pcall(function() m = n:getInputNodeIx(i) end)
            if m ~= nil and hasProjection(m) then
                foundtex = true
                project(m)
            end
        end
    end
end

if foundtex then
    octane.changemanager.update()
else
    error("You have to select an image texture node or material node.")
end