freesewing/packages/titan/drafting-instructions.md

Titan drafting instructions

As provided by @dfbean

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Action	# Value	Draft value (cm)	Code value (mm)	Drafter comments	Programmer comments
Make a point, label A
Square line down # from A, mark point at end, label D	crotch depth	31.1	311		used crotchDepth measurement
On line A-D, measure # from point A, mark new point, label C	hip depth	22.9	229		used naturalWaistToSeat measurement
From point A, square a line # left, mark endpoint, label H	back hip arc + .3cm	28.2	-281.79	.3cm for ease	used hipsEase option, backHipArc measurement provided by the measurements plugin (part of titan for now)
From point C, square a line # left, mark endpoint, label F	back hip arc + .3cm	28.2	-281.79	.3cm for ease
From point D, square a line #, mark endpoint, label I	Use greater of 1.25 x (back hip arc + .3)	35.3	352.2375	this step incorporates a subsequent fit check, and includes some adjustments required to draft this piece independent of the front piece.
	OR, (upperleg + 3.8 + 1.9) – (front hip arc + .3+ front crotch extension)	(64.8 + 3.8 + 1.9) – (25.4 +.3 +5.7) = 39.1	393.23	Includes 3.8 cm recommended crotch ease and 1.9cm placeholder that will be removed later.	used upperLegEase and crotchExtension options. crotchExtension being based on hipsCircumference measurement
Starting at point H, square down through point F, till intersecting with line D-I. Label intersection point G
On line G-H, measure # from point G, mark endpoint, label X	.5(crotch depth)	15.6	155.5
On line A-H, measure # from point H, toward point A, mark point, label N	4.5	4.5	45.1	Fixed value, sets reference point for back waist	This doesn't work for us. We can't just put in an arbitrary 4.5cm value. That doesn't scale. So I've added a static option called backWaistFactor that is 14.5% of the crotchDepth measurement. That way, the slant of the back seam should always be the same. This might need tweaking though.
On line A-H, measure from point N toward point A, # mark endpoint, label O	back waist arc + 2.5	22.8	227.36	2.5 fixed value for dart width. Ok that it's fixed, it's mostly a placeholder and gets removed, rolled or replaced in pant patterns. If additional shaping is required it can be placed in hip curve.	I've added the backWaistDart option which is 12% of the backWaistArc measurement, which gives us 24.36mm
On line A-H, measure from point N # toward O, mark endpoint, label P	.5 (back waist arc + 2.5)	11.4	113.68	2.5 fixed value for dart placement.	went with time .56 instead of fixed value
Square line # down from P, mark endpoint, no label		8.9	88.64	Fixed value for dart length. See previous note onfixed dart value.	Added the backWaistDartLength option, which is based on the crotchDepth measurement. 28.5% by default
Square out # from P on both sides, mark endpoints, no label.		1.0	12.5	1.0 Fixed value for dart width. See previous note.	Earlier on, draft instructions specify 2.5cm fixed value for dart width. Now, it's 1cm fixed value for (half of the) dart width. Rather than an introduce a 0.5cm error, I've kept the dart width at 2.5 cm (12.5mm to each side).
Square up # from point N, mark endpoint, label T	2.5	2.5	-24.88	Fixed value for height of back rise.	Once again not loving the fixed 2.5cm value here. But I'm not certain whether it's best to make this a fraction of crotchDepth or rather backWaistArc. Went with crotchDepth since it is a vertical measurement after all. Added the backRise option for this.
Draw a line from T, through X, to line D-I, no label			-320.67		Point name: extendedBackSeam
Square # up/left diagonally from G , mark endpoint, label g	4.4	4.4	44	Fixed value as reference for crotch curve.	I'm a bit confused here about the fixed value note here. The intersection of the line from T through X and a line from G 45 degrees NW can only intersect in 1 point. It so happens that point is 4.4cm from G, but why is it described as a fixed value?
Draw curve touching X and g, ending at/near I, blend at g if needed.					I had a look at the hand-drawn version, and I do find the bend of this curve to be really sharp. I have approximated it in the code, but I have also added the backSeamCurveStart and backSeamCurveBend options to control the curvature.
Draw slightly curved line from T to O.
Draw dart legs through side points, up to curved T-O line
True dart by raising shorter leg and redrawing line to O.				We don't true, we just get it right :)
Draw hip curve from just above C to O					Just above C? Why just above C as C marks the fullest part of the seat?
On line D-I, mark new point # to left of D, label V	1	1	9.84	Fixed point as reference for hip curve. This value was already included in line D-I, so that it could be removed at this stage.	This seems a bit random. I don't see any reference to 1cm when constructing point I, so not sure where to get this from. See next step for workaround
On line D-I, mark new point # halfway between between V and I, label W		19.0	191.5	I measured/divided manually, you'll let the computer do this.	Went with 51.25% instead (because of the 1cm). Stored in the static grainlineBackFactor option
From point W, square up to line A-H (waistline) and down # waist to ankle, to knee and # to ankle to create grainline Mark knee and ankle points		100.3, 61.0	1053, 610	Threw this in so I could complete the crotch and hip curves.	We have a naturalWaistToFloor measurement. Adding naturalWaistToAnkle seems excessive. I'm drafting this block to the floor and will leave it to the designer how long they want things. I guesstimated 105.3cm for the fit model.
At knee point square and center a # line, mark endpoints, no label	(knee circ / 2) + 2.5	(40.6/2) + 2.5 = 22.8	221.2	Knee and ankle circs are needed to build hip and crotch curves correctly. I used my measurement with 1 inch of ease allocated to the back. I want to fiddle with this and get your comments.	Is it custom to only apply ease to the back? I've added a kneeEase options for this combined with that legBalance option to control this. Default = 75% (meaning that 75% of ease is applied to the back)
At ankle point, square and center a line, mark endpoints, no label	(ankle entry circ / 2) - 2.5	(31.8/2) + 2.5 = 18.4	173.4	Same approach as the knee, just to have a point to work with. See above note about revisiting after testing.	I noticed we don't have an ankleCircumference measurement, but only ankleEntry. I've based it on the latter for now, but this feels a bit contra-intuitive. Added ankleEase option for this.
Draw a line from ankle points, through knee points, to line D-I.			Creates in/out seams and guide for hip and crotch curves
Draw curve down from I to inseam, blending curve into seam about midway between knee and line D-I. Ensure first inch of curve down from I is at 90 degree angle to upward curve from I.					Ignored the 90 degree thing for now. Added inseamCurve option to control shape of curve.
Draw curve down from V to outseam, blending curve into seam about midway between knee and line D-I.					I've added the outSeamCurveKnee and outSeamCurveSeat options to control this. Set the defaults so that the curve deviates 1cm (9.66mm to be exact) at the D-I line as instructed earlier
Correct crotch length by pitching crotch seam up/down at point F.	back crotch length – (T-X-g-I) = pitch up	45.2 – 40 = 5.2		Lucky you, the computer will handle this! Negative result means downward pitch	Implemented by slashing horizontally, then rotating, in combination with shifting the tip of the inseam outwards. The balance between these two ways to increase (or decrease) the cross seam is the crossSeamFitBalance option which defaults to 0.5. Once the cross seam is the correct length, we also make sure we respect the horizontal distance from cross seam to side by shifting the side seam outwards.

Front

Action	# Value	Draft value (cm)	Code value (mm)	Drafter comments	Programmer comments
Make a point, label A
Square line down # from A, mark point at end, label D	crotch depth	31.1	311		used crotchDepth measurement
On line A-D, measure # from point A, mark new point, label C	hip depth	22.9	229		used naturalWaistToSeat measurement
From point A, square a line # right mark endpoint, label L	front hip arc + .3cm	25.4 + .3 = 25.7	256.54	.3cm for ease	used hipsEase option, frontHipArc measurement provided by the measurements plugin (part of titan for now)
From point C, square a line # right, mark endpoint, label J	front hip arc + .3cm	25.4 + .3 = 25.7	256.54	.3cm for ease
From point D, square a line # right, mark endpoint, label K	front hip arc + .3cm	25.4 + .3 = 25.7	256.54	.3 cm for ease
Extend line D-K # to the right, label endpoint M	crotch extension				Used crotchExtension option (same as back) as basis but applied a 7% extra stored in fixed option crotchFrontExtention
Connect L to K touching J
On line L-K, measure # from point from K, mark endpoint, label X	.5(crotch depth) + 1.3	15.5 + 1.3 = 16.8	18.8		Went with 54% of crotchDepth instead. Created a new option for this: flySlopeHinge, fixed to 0.54
On line A-L, measure # from point L, mark point, label Q	1.3	1.3	12.88		Based this on the vertical distance between X and L, this should keep the slop consistent across sizes. Created new option for this: flySlopeFactor, fixed to 0.09
On line A-L, measure # from point Q toward point A, mark endpoint, label R	front waist arc + 1.9	20.3 + 1.9 = 22.2	19.05	1.9 fixed value for dart width. OK that it's fixed, it's mostly a placeholder and gets removed, rolled or replaced in pant patterns. If additional shaping is required it can be placed in hip curve.	Added the frontWaistDart option which defaults to 7.5%
On line A-L, measure # from point Q toward R, mark endpoint, label S	8.3	8.3	81.9	fixed value for dart placement. See previous note on fixed dart value	Went with frontWaistDartLocation option which is be default 30% from Q towards R
Square line # down from S, mark endpoint, no label	6.4	6.4	64.38	Fixed value for dart length. See previous note on fixed dart value.	Went with frontWaistDartLenght option, which defaults to 45% (based on distance down to X)
Square out # from S on both sides, mark endpoints, no label.	.6	.6	6.35	Fixed value for dart width. See previous note.	Earlier, you used 1.9 as a fixed value for dart with. Now, half the dart width is 0.6 7mm went missing somewhere and I can't see what happened to them. So, I aimed for 12.7mm dart width and am thus not respecting the 19mm above
Square up # from point Q, mark endpoint, label U	.6	.6	6.35	Fixed value for waistband reference	Created frontWaistRise options for this, defaults to 2.5% (of frontWaistArc measurement)
Draw a line from U, through X, to line D-K-M, no label
Square # up/right diagonally from K , mark endpoint, label k	3.2	3.2		Fixed value as reference for crotch curve.	Didn't bother with this, as it's not a point we'll use in construction, but merely an indicator where our curve should be.
Draw curve touching X, k and M, blend at k if needed.					Similar options as the back: flyCurveStart and flyCurveBend
Draw slightly curved line from U to R					If there's a curve in your drawing, it's too subtle to see. So I just used a straight line as that makes handling the dart so so much easier. On that note, we've already constructed the dart at this point. Now we don't only have to move it, but it's also no longer on a horizontal line, so we have to slightly rotate it. AS such, I'm going to move the construction of the dart further down the code so that we construct it in the right place rather than moving it afterwards.
Draw dart legs through side points, up to curved U-R line
True dart by raising shorter leg and redrawing line to R					No trueing needed, our dart is correct already
Draw hip curve from just above C to R					Same remark as for the back: Why just above C as C marks the fullest part of the seat?
On line D-M, mark new point # to right of D, label Y	1.0	1.0		Fixed point as reference for hip curve. This value was already included in line D-I, so that it could be removed at this stage.	This is one of those control points not actuall used in construction. Will just use 52% of the horizontal distance instead, stored in the frontGrainLineFactor option
On line D-M, mark new point halfway between between Y and M, label Z		15.2	153	Value only for reference, you use that new-fangled computer to generate this.	Why did we go through all that trouble figuring out where to put the dart, when we now determine this is the grainline, which is probably where the dart should be anyway?
From point Z, square up to line A-L (waistline) and down # to waist to ankle, knee and # to ankle to create grainline Mark knee and ankle waist to knee points		100.3
At knee point square and center a # line, mark endpoints, no label	knee circ / 2	40.6/2 = 20.3	209.1	Threw this in so I could complete the crotch and hip curves. Knee and ankle circ”s are needed to build hip and crotch curves correctly. I used my measurements with 1 inch of ease at knee, allocated to the back. I want to fiddle with this and get your comments.	I used the kneeEase and legBalance options for this (same as in the back). Hence slightly different value
At ankle point, square and center a line, mark endpoints, no label	ankle entry circ / 2	31.8/2 = 15.9	163.76 because we added ankleEase	Same approach as the knee, just to have a point to work with. See above note about revisiting after testing.	Note that we're drafting to the floor
Draw a line from ankle points, through knee points, to line D-M Creates in/out seams and guide for hip and crotch curves
Draw curve down from M to inseam, blending curve into seam about midway between knee and line D-M. Ensure first inch of curve down from M is at 90 degree angle to upward curve from M.
Draw curve down from Y to outseam, blending curve into seam about midway between knee and line D-M.
Correct crotch length by pitching crotch seam up/down at point J

All implemented. And more. For one thing, there's no trueing of the inseam and outseam here.