modlib/minetest/collisionboxes.lua

-- Minetest allows shorthand collisionbox = {...} instead of {{...}}
local function get_collisionboxes(box_or_boxes)
    return type(box_or_boxes[1]) == "number" and {box_or_boxes} or box_or_boxes
end

--> list of collisionboxes in Minetest format
function get_node_collisionboxes(pos)
    local node = minetest.get_node(pos)
    local node_def = minetest.registered_nodes[node.name]
    if (not node_def) or node_def.walkable == false then
        return {}
    end
    local boxes = {{-0.5, -0.5, -0.5, 0.5, 0.5, 0.5}}
    local def_collision_box = node_def.collision_box or (node_def.drawtype == "nodebox" and node_def.node_box)
    if def_collision_box then
        local box_type = def_collision_box.type
        if box_type == "regular" then
            return boxes
        end
        local fixed = def_collision_box.fixed
        boxes = get_collisionboxes(fixed or {})
        local paramtype2 = node_def.paramtype2
        if box_type == "leveled" then
            boxes = table.copy(boxes)
            local level = (paramtype2 == "leveled" and node.param2 or node_def.leveled or 0) / 255 - 0.5
            for _, box in pairs(boxes) do
                box[5] = level
            end
        elseif box_type == "wallmounted" then
            -- TODO complete if only wall_top is given
            local dir = minetest.wallmounted_to_dir((paramtype2 == "colorwallmounted" and node.param2 % 8 or node.param2) or 0)
            local box
            if dir.y > 0 then
                box = def_collision_box.wall_top
            elseif dir.y < 0 then
                box = def_collision_box.wall_bottom
            else
                box = def_collision_box.wall_side
                if dir.z > 0 then
                    box = {box[3], box[2], -box[4], box[6], box[5], -box[1]}
                elseif dir.z < 0 then
                    box = {-box[6], box[2], box[1], -box[3], box[5], box[4]}
                elseif dir.x > 0 then
                    box = {-box[4], box[2], box[3], -box[1], box[5], box[6]}
                else
                    box = {box[1], box[2], -box[6], box[4], box[5], -box[3]}
                end
            end
            return {assert(box, "incomplete wallmounted collisionbox definition of " .. node.name)}
        end
        if box_type == "connected" then
            boxes = table.copy(boxes)
            local connect_sides = {
                top = {x = 0, y = 1, z = 0},
                bottom = {x = 0, y = -1, z = 0},
                front = {x = 0, y = 0, z = -1},
                left = {x = -1, y = 0, z = 0},
                back = {x = 0, y = 0, z = 1},
                right = {x = 1, y = 0, z = 0}
            }
            if node_def.connect_sides then
                for side in pairs(connect_sides) do
                    if not node_def.connect_sides[side] then
                        connect_sides[side] = nil
                    end
                end
            end
            local function add_collisionbox(key)
                for _, box in ipairs(get_collisionboxes(def_collision_box[key] or {})) do
                    table.insert(boxes, box)
                end
            end
            local matchers = {}
            for _, nodename_or_group in pairs(node_def.connects_to or {}) do
                table.insert(matchers, nodename_matcher(nodename_or_group))
            end
            local function connects_to(nodename)
                for _, matcher in pairs(matchers) do
                    if matcher(nodename) then
                        return true
                    end
                end
            end
            local connected, connected_sides
            for side, direction in pairs(connect_sides) do
                local neighbor = minetest.get_node(vector.add(pos, direction))
                local connects = connects_to(neighbor.name)
                connected = connected or connects
                connected_sides = connected_sides or (side ~= "top" and side ~= "bottom")
                add_collisionbox((connects and "connect_" or "disconnected_") .. side)
            end
            if not connected then
                add_collisionbox("disconnected")
            end
            if not connected_sides then
                add_collisionbox("disconnected_sides")
            end
            return boxes
        end
        if box_type == "fixed" and paramtype2 == "facedir" or paramtype2 == "colorfacedir" then
            local param2 = paramtype2 == "colorfacedir" and node.param2 % 32 or node.param2 or 0
            if param2 ~= 0 then
                boxes = table.copy(boxes)
                local axis = ({5, 6, 3, 4, 1, 2})[math.floor(param2 / 4) + 1]
                local other_axis_1, other_axis_2 = (axis % 3) + 1, ((axis + 1) % 3) + 1
                local rotation = (param2 % 4) / 2 * math.pi
                local flip = axis > 3
                if flip then axis = axis - 3; rotation = -rotation end
                local sin, cos = math.sin(rotation), math.cos(rotation)
                if axis == 2 then
                    sin = -sin
                end
                for _, box in pairs(boxes) do
                    for off = 0, 3, 3 do
                        local axis_1, axis_2 = other_axis_1 + off, other_axis_2 + off
                        local value_1, value_2 = box[axis_1], box[axis_2]
                        box[axis_1] = value_1 * cos - value_2 * sin
                        box[axis_2] = value_1 * sin + value_2 * cos
                    end
                    if not flip then
                        box[axis], box[axis + 3] = -box[axis + 3], -box[axis]
                    end
                    local function fix(coord)
                        if box[coord] > box[coord + 3] then
                            box[coord], box[coord + 3] = box[coord + 3], box[coord]
                        end
                    end
                    fix(other_axis_1)
                    fix(other_axis_2)
                end
            end
        end
    end
    return boxes
end