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Fix handling of multiple texmod transforms
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Lars Mueller
parent
e07d646203
commit
8e5bdc817c
@ -123,35 +123,106 @@ function texmod:invert(channels --[[set with keys "r", "g", "b", "a"]])
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end
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function texmod:flip(flip_axis --[["x" or "y"]])
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assert(flip_axis == "x" or flip_axis == "y")
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return new{
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type = "transform",
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base = self,
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flip_axis = flip_axis
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}
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return self:transform(assert(
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(flip_axis == "x" and "fx")
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or (flip_axis == "y" and "fy")
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or (not flip_axis and "i")))
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end
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function texmod:rotate(deg)
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assert(deg % 90 == 0)
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deg = deg % 360
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assert(deg % 90 == 0, "only multiples of 90° supported")
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return new{
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type = "transform",
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base = self,
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rotation_deg = deg
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}
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return self:transform(("r%d"):format(deg))
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end
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-- First flip, then rotate counterclockwise
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function texmod:transform(flip_axis, rotation_deg)
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assert(flip_axis == nil or flip_axis == "x" or flip_axis == "y")
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rotation_deg = (rotation_deg or 0) % 360
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assert(rotation_deg % 90 == 0, "only multiples of 90° supported")
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return new{
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type = "transform",
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base = self,
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rotation_deg = rotation_deg ~= 0 and rotation_deg or nil,
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flip_axis = flip_axis
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-- D4 group transformations (see https://proofwiki.org/wiki/Definition:Dihedral_Group_D4),
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-- represented using indices into a table of matrices
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-- TODO (...) try to come up with a more elegant solution
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do
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-- Matrix multiplication for composition: First applies a, then b <=> b * a
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local function mat_2x2_compose(a, b)
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local a_1_1, a_1_2, a_2_1, a_2_2 = unpack(a)
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local b_1_1, b_1_2, b_2_1, b_2_2 = unpack(b)
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return {
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a_1_1 * b_1_1 + a_2_1 * b_1_2, a_1_2 * b_1_1 + a_2_2 * b_1_2;
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a_1_1 * b_2_1 + a_2_1 * b_2_2, a_1_2 * b_2_1 + a_2_2 * b_2_2
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}
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end
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local r90 ={
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0, -1;
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1, 0
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}
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local fx = {
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-1, 0;
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0, 1
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}
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local fy = {
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1, 0;
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0, -1
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}
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local r180 = mat_2x2_compose(r90, r90)
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local r270 = mat_2x2_compose(r180, r90)
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local fxr90 = mat_2x2_compose(fx, r90)
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local fyr90 = mat_2x2_compose(fy, r90)
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local transform_mats = {[0] = {1, 0; 0, 1}, r90, r180, r270, fx, fxr90, fy, fyr90}
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local transform_idx_by_name = {i = 0, r90 = 1, r180 = 2, r270 = 3, fx = 4, fxr90 = 5, fy = 6, fyr90 = 7}
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-- Lookup tables for getting the flipped axis / rotation angle
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local flip_by_idx = {
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[4] = "x",
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[5] = "x",
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[6] = "y",
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[7] = "y",
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}
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local rot_by_idx = {
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[1] = 90,
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[2] = 180,
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[3] = 270,
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[5] = 90,
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[7] = 90,
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}
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local idx_by_mat_2x2 = {}
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local function transform_idx(mat)
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-- note: assumes mat[i] in {-1, 0, 1}
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return mat[1] + 3*(mat[2] + 3*(mat[3] + 3*mat[4]))
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end
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for i = 0, 7 do
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idx_by_mat_2x2[transform_idx(transform_mats[i])] = i
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end
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-- Compute a multiplication table
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local composition_idx = {}
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local function ij_idx(i, j)
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return i*8 + j
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end
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for i = 0, 7 do
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for j = 0, 7 do
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composition_idx[ij_idx(i, j)] = assert(idx_by_mat_2x2[
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transform_idx(mat_2x2_compose(transform_mats[i], transform_mats[j]))])
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end
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end
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function texmod:transform(...)
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if select("#", ...) == 0 then return self end
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local idx = ...
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if type(idx) == "string" then
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idx = assert(transform_idx_by_name[idx:lower()])
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end
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local base = self
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if self.type == "transform" then
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-- Merge with a `^[transform` base image
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assert(transform_mats[idx])
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base = self.base
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idx = composition_idx[ij_idx(self.idx, idx)]
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end
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assert(transform_mats[idx])
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if idx == 0 then return base end -- identity
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return new{
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type = "transform",
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base = base,
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idx = idx,
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-- Redundantly store this information for convenience. Do not modify!
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flip_axis = flip_by_idx[idx],
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rotation_deg = rot_by_idx[idx] or 0,
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}:transform(select(2, ...))
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end
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end
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function texmod:verticalframe(framecount, frame)
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@ -256,4 +327,4 @@ function texmod:lowpart(percent, overlay)
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}
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end
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return texmod, metatable
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return texmod, metatable
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@ -79,34 +79,25 @@ function pr.invert(r)
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end
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do
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local transforms = {
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[0] = {},
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{rotation_deg = 90},
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{rotation_deg = 180},
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{rotation_deg = 270},
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{flip_axis = "x"},
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{flip_axis = "x", rotation_deg = 90},
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{flip_axis = "y"},
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{flip_axis = "y", rotation_deg = 90},
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}
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function pr.transform(r)
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-- Note: While it isn't documented, `[transform` is indeed case-insensitive.
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if r:match_charset"[iI]" then
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return
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return pr.transform(r)
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end
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local idx = r:match_charset"[0-7]"
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if idx then
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return tonumber(idx), pr.transform(r)
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end
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local flip_axis
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if r:match_charset"[fF]" then
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flip_axis = assert(r:match_charset"[xXyY]", "axis expected"):lower()
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local flip_axis = assert(r:match_charset"[xXyY]", "axis expected")
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return "f" .. flip_axis, pr.transform(r)
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end
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local rot_deg
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if r:match_charset"[rR]" then
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rot_deg = r:int()
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local deg = r:match_str"%d"
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-- Be strict here: Minetest won't recognize other ways to write these numbers (or other numbers)
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assert(deg == "90" or deg == "180" or deg == "270")
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return ("r%d"):format(deg), pr.transform(r)
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end
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if flip_axis or rot_deg then
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return flip_axis, rot_deg
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end
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local transform = assert(transforms[r:int()], "out of range")
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return transform.flip_axis, transform.rotation_deg
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-- return nothing, we're done
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end
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end
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@ -329,4 +320,4 @@ return function(read_char)
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local res = r:texp()
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assert(r.eof, "eof expected")
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return res
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end
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end
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@ -51,28 +51,7 @@ function pw:invert(w)
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end
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function pw:transform(w)
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local rot_deg, flip_axis = self.rotation_deg or 0, self.flip_axis
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if rot_deg == 0 and flip_axis == nil then
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w.str"I"
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elseif rot_deg == 0 then
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w.str(assert(({x = "FX", y = "FY"})[flip_axis]))
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elseif flip_axis == nil then
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w.str"R"; w.int(self.rotation_deg)
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elseif rot_deg == 90 then
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w.str(assert(({x = "FX", y = "FY"})[flip_axis]))
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w.str"R90"
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elseif rot_deg == 180 then
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-- Rotating by 180° is equivalent to flipping both axes;
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-- if one axis was already flipped, that is undone -
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-- thus it is equivalent to flipping the other axis
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w.str(assert(({x = "FY", y = "FX"})[flip_axis]))
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elseif rot_deg == 270 then
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-- Rotating by 270° is equivalent to first rotating by 180°, then rotating by 90°;
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-- first flipping an axis and then rotating by 180°
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-- is equivalent to flipping the other axis as shown above
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w.str(assert(({x = "FY", y = "FX"})[flip_axis]))
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w.str"R90"
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end
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w.int(self.idx)
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end
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function pw:verticalframe(w)
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@ -172,4 +151,4 @@ return function(self, write_str)
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w.level = w.level - 1
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end
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w.tex(self)
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end
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end
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