modlib/minetest/raycast.lua
2021-06-17 19:45:08 +02:00

139 lines
4.9 KiB
Lua

-- Localize globals
local assert, math, minetest, modlib, pairs, setmetatable, vector = assert, math, minetest, modlib, pairs, setmetatable, vector
-- Set environment
local _ENV = ...
setfenv(1, _ENV)
--+ Raycast wrapper with proper flowingliquid intersections
function raycast(_pos1, _pos2, objects, liquids)
local raycast = minetest.raycast(_pos1, _pos2, objects, liquids)
if not liquids then
return raycast
end
local pos1 = modlib.vector.from_minetest(_pos1)
local _direction = vector.direction(_pos1, _pos2)
local direction = modlib.vector.from_minetest(_direction)
local length = vector.distance(_pos1, _pos2)
local function next()
for pointed_thing in raycast do
if pointed_thing.type ~= "node" then
return pointed_thing
end
local _pos = pointed_thing.under
local pos = modlib.vector.from_minetest(_pos)
local node = minetest.get_node(_pos)
local def = minetest.registered_nodes[node.name]
if not (def and def.drawtype == "flowingliquid") then return pointed_thing end
local corner_levels = get_liquid_corner_levels(_pos)
local full_corner_levels = true
for _, corner_level in pairs(corner_levels) do
if corner_level[2] < 0.5 then
full_corner_levels = false
break
end
end
if full_corner_levels then
return pointed_thing
end
local relative = pos1 - pos
local inside = true
for _, prop in pairs(relative) do
if prop <= -0.5 or prop >= 0.5 then
inside = false
break
end
end
local function level(x, z)
local function distance_squared(corner)
return (x - corner[1]) ^ 2 + (z - corner[3]) ^ 2
end
local irrelevant_corner, distance = 1, distance_squared(corner_levels[1])
for index = 2, 4 do
local other_distance = distance_squared(corner_levels[index])
if other_distance > distance then
irrelevant_corner, distance = index, other_distance
end
end
local function corner(off)
return corner_levels[((irrelevant_corner + off) % 4) + 1]
end
local base = corner(2)
local edge_1, edge_2 = corner(1) - base, corner(3) - base
-- Properly selected edges will have a total length of 2
assert(math.abs(edge_1[1] + edge_1[3]) + math.abs(edge_2[1] + edge_2[3]) == 2)
if edge_1[1] == 0 then
edge_1, edge_2 = edge_2, edge_1
end
local level = base[2] + (edge_1[2] * ((x - base[1]) / edge_1[1])) + (edge_2[2] * ((z - base[3]) / edge_2[3]))
assert(level >= -0.5 and level <= 0.5)
return level
end
inside = inside and (relative[2] < level(relative[1], relative[3]))
if inside then
-- pos1 is inside the liquid node
pointed_thing.intersection_point = _pos1
pointed_thing.intersection_normal = vector.new(0, 0, 0)
return pointed_thing
end
local function intersection_normal(axis, dir)
return {x = 0, y = 0, z = 0, [axis] = dir}
end
local function plane(axis, dir)
local offset = dir * 0.5
local diff_axis = (relative[axis] - offset) / -direction[axis]
local intersection_point = {}
for plane_axis = 1, 3 do
if plane_axis ~= axis then
local value = direction[plane_axis] * diff_axis + relative[plane_axis]
if value < -0.5 or value > 0.5 then
return
end
intersection_point[plane_axis] = value
end
end
intersection_point[axis] = offset
return intersection_point
end
if direction[2] > 0 then
local intersection_point = plane(2, -1)
if intersection_point then
pointed_thing.intersection_point = (intersection_point + pos):to_minetest()
pointed_thing.intersection_normal = intersection_normal("y", -1)
return pointed_thing
end
end
for coord, other in pairs{[1] = 3, [3] = 1} do
if direction[coord] ~= 0 then
local dir = direction[coord] > 0 and -1 or 1
local intersection_point = plane(coord, dir)
if intersection_point then
local height = 0
for _, corner in pairs(corner_levels) do
if corner[coord] == dir * 0.5 then
height = height + (math.abs(intersection_point[other] + corner[other])) * corner[2]
end
end
if intersection_point[2] <= height then
pointed_thing.intersection_point = (intersection_point + pos):to_minetest()
pointed_thing.intersection_normal = intersection_normal(modlib.vector.index_aliases[coord], dir)
return pointed_thing
end
end
end
end
for _, triangle in pairs{
{corner_levels[3], corner_levels[2], corner_levels[1]},
{corner_levels[4], corner_levels[3], corner_levels[1]}
} do
local pos_on_ray = modlib.vector.ray_triangle_intersection(relative, direction, triangle)
if pos_on_ray and pos_on_ray <= length then
pointed_thing.intersection_point = (pos1 + modlib.vector.multiply_scalar(direction, pos_on_ray)):to_minetest()
pointed_thing.intersection_normal = modlib.vector.triangle_normal(triangle):to_minetest()
return pointed_thing
end
end
end
end
return setmetatable({next = next}, {__call = next})
end