inktracetut

This is now outdated and still unfinished as of 2005-04-02.

I've started writing a basic tutorial on how I use Inkscape to quickly trace out a guitar body design. If I hear that someone wants to read it, I might even finish it.

Creating a body template with Inkscape and Whibet UCP.

Set up an Inkscape document:

Open the document properties with CTRL+SHIFT+D. I like to set the canvas border to visible and make it on top of other objects. This helps me keep the body inside of the bounds that I set for it. The grid is a huge help. I set grid spacing to a quarter inch in both directions. The only thing that could possibly be cooler about the grid would be alternating colors or perhaps major and minor units. To mimic this I often place guides every inch in addition to my grid. You can place a guide by clicking a ruler and dragging onto the document. If you want guides wait to place them until after you resize the canvas. Don't worry about resizing the canvas now. We'll do that later. If you are a bit technically inclined you can save yourself the setup time on future products by opening the XML editor and copying the document properties section into the template section of the preferences.xml file for Inkscape. If you are funny about round numbers like I am you may want to examine all of the snapping options in the document preferences and the step options in the global property dialog. I want to alert you to one last and very very cool option that can be found in the global Inkscape preference dialog: transform preserve / optimize. For our purposes optimize is best as all transformations will actually modify the path we will be working with instead of stacking up in the transform attribute.

Select an appropriate image:

In my mind the most appropriate images are full frontal views that show everything from the tip of the headstock down to the endpin. A body only shot will work fine if you know the basic body dimensions (otherwise the scaling process can be more difficult). Because we are tracing, it is important that the guitar is straight in the picture. Follow a line down the center of the neck and check the symmetry to make sure it is straight. Look at the body. You want a perfect silhouette with no view of the sides of the body. If images are hard to come by, you can always fix one up with the rotate, shear and perspective tools in the GIMP. I usually look for 400px and larger sized images. Images need not be large to give a good idea of how a body is shaped. If you are looking for a popular body style a google image search can give quick results. If you have more exotic tastes you may have to scour dealer and fan sites. Once you have a good image. Save it and add it to your Inkscape document with the import button or tap CTRL+I.

Scale the image:

If you don't know the exact body dimensions you can help yourself scale the image by creating a helper rectangle. I make a rectangle as high as the scale length of the guitar I'm drawing. If I don't know the scale I guess between 24.5 and 25.5 inches for guitars and around 34 for basses. Bridge and pickup width rectangles will also work but are smaller and therefore give greater error. To drag a rectangle select the rectangle tool, find the scale length on the ruler and drag down from there to 0. If you don't care for dragging, create a small rectangle, right click on it and open the rectangle properties. You can adjust the height there. Inkscape stores rectangles in SVG user units. In Inkscape that is 90 units to an inch. So 34 inches is 3060 units, 24.5 inches is 2205 units and 25.5 is 2295 units.

Now grab your image with the select and transform tool. Be careful of clicking twice because it can put you into rotate mode (if you are already there click the image again to return to scaling mode. Drop the image to the bottom layer of the document with the lower to bottom button in the transform toolbar or tap END. Now the rectangle will show on top of the picture. If you want to drag to scale the image hold down CTRL, grab a corner and drag around until the helper rectangle fits perfectly between the nut and the high e string bridge saddle. If you prefer not to drag, find your way up to the transform toolbar, click the lock to change height and width in the same proportion, change units into percent and use the spinners to scale your image.

Size the canvas:

Ascertain the body dimensions. I usually eyeball the body against the gird, round a bit and rescale the body. If you want exactness you could make helper rectangles and find the correct values in their properties. Open the document properties and change the canvas size to be large enough to hold the body. Drag the body onto the canvas. If the picture is selected you can use the arrow keys to nudge it around.

Make a basic path:

I use the bezier curve and straight line tool to rough out the outline. If you have no prior exposure to bezier curves you should probably play around for a while until you are comfortable with the tool and see what sorts of curve segments you can create. You may even want to google for a little bezier tutorial to get warmed up. Once you are ready start placing nodes. Click to place a node. Click and drag if you want to curve it right away. I usually make straight segments first and tweak the control points later. There probably is a proper method for placing nodes and it probably involves calculus and finding the inflection points of the curve, but I don't know this method. I start at the neck/body joint and place a node, place a node at the bottom of the cutout, tip of the horn, outside of the upper bout, the waist, lower bout, endpin and continue up the other side. In addition any sharp point will need a node. Click on the first node (it should turn red when you point at it) to close the path. It is ok if this is very rough. Nodes can be added, removed and moved as need be.

Adjust the path:

node tool. to curve. smooth round nodes (gives perfect beautiful curves). to corner + to line around neck.

Borrow the path:

Now that you have completed tweaking the path in Inkscape, let's borrow the path data for our use in Whibet UCP. open xml editor, select path, select "d" attribute, tripple click pathdata and copy to whibet ucp. enter the height of your drawing in the "Inkscape" box and click "From". I often round my pathdata off to the nearest 16th of an inch because I like round numbers and it is simple way to "compress" the path data. If you spent a long time drawing a perfect scale copy of a guitar, you probably don't want to do that because it will noticeable change your lines.

Make PDF:

If you are daring you can use Whibet to do various translating and scaling transformations to the body. for instance you may want to move the path up and to the right so that it is more centered in the print out. If not, you are done. enter the width and height of the path you drew in the viewbox boxes and click "Make PDF" to get a scaled printable version of all of your hard work.

Closing:

I'm sure there are many easier ways to get a printable guitar body template. Whibet UCP uses SVG and PDF paths in conjunction with FPDF and PHP. My plan is to someday add basic guitar plan generation to FretFind 2-D. If you would like to see this happen please drop me a line.

Aaron Spike


			Home Compute Contact


		This is now outdated and still unfinished as of 2005-04-02. I've started writing a basic tutorial on how I use Inkscape to quickly trace out a guitar body design. If I hear that someone wants to read it, I might even finish it. Creating a body template with Inkscape and Whibet UCP. Set up an Inkscape document: Open the document properties with CTRL+SHIFT+D. I like to set the canvas border to visible and make it on top of other objects. This helps me keep the body inside of the bounds that I set for it. The grid is a huge help. I set grid spacing to a quarter inch in both directions. The only thing that could possibly be cooler about the grid would be alternating colors or perhaps major and minor units. To mimic this I often place guides every inch in addition to my grid. You can place a guide by clicking a ruler and dragging onto the document. If you want guides wait to place them until after you resize the canvas. Don't worry about resizing the canvas now. We'll do that later. If you are a bit technically inclined you can save yourself the setup time on future products by opening the XML editor and copying the document properties section into the template section of the preferences.xml file for Inkscape. If you are funny about round numbers like I am you may want to examine all of the snapping options in the document preferences and the step options in the global property dialog. I want to alert you to one last and very very cool option that can be found in the global Inkscape preference dialog: transform preserve / optimize. For our purposes optimize is best as all transformations will actually modify the path we will be working with instead of stacking up in the transform attribute. Select an appropriate image: In my mind the most appropriate images are full frontal views that show everything from the tip of the headstock down to the endpin. A body only shot will work fine if you know the basic body dimensions (otherwise the scaling process can be more difficult). Because we are tracing, it is important that the guitar is straight in the picture. Follow a line down the center of the neck and check the symmetry to make sure it is straight. Look at the body. You want a perfect silhouette with no view of the sides of the body. If images are hard to come by, you can always fix one up with the rotate, shear and perspective tools in the GIMP. I usually look for 400px and larger sized images. Images need not be large to give a good idea of how a body is shaped. If you are looking for a popular body style a google image search can give quick results. If you have more exotic tastes you may have to scour dealer and fan sites. Once you have a good image. Save it and add it to your Inkscape document with the import button or tap CTRL+I. Scale the image: If you don't know the exact body dimensions you can help yourself scale the image by creating a helper rectangle. I make a rectangle as high as the scale length of the guitar I'm drawing. If I don't know the scale I guess between 24.5 and 25.5 inches for guitars and around 34 for basses. Bridge and pickup width rectangles will also work but are smaller and therefore give greater error. To drag a rectangle select the rectangle tool, find the scale length on the ruler and drag down from there to 0. If you don't care for dragging, create a small rectangle, right click on it and open the rectangle properties. You can adjust the height there. Inkscape stores rectangles in SVG user units. In Inkscape that is 90 units to an inch. So 34 inches is 3060 units, 24.5 inches is 2205 units and 25.5 is 2295 units. Now grab your image with the select and transform tool. Be careful of clicking twice because it can put you into rotate mode (if you are already there click the image again to return to scaling mode. Drop the image to the bottom layer of the document with the lower to bottom button in the transform toolbar or tap END. Now the rectangle will show on top of the picture. If you want to drag to scale the image hold down CTRL, grab a corner and drag around until the helper rectangle fits perfectly between the nut and the high e string bridge saddle. If you prefer not to drag, find your way up to the transform toolbar, click the lock to change height and width in the same proportion, change units into percent and use the spinners to scale your image. Size the canvas: Ascertain the body dimensions. I usually eyeball the body against the gird, round a bit and rescale the body. If you want exactness you could make helper rectangles and find the correct values in their properties. Open the document properties and change the canvas size to be large enough to hold the body. Drag the body onto the canvas. If the picture is selected you can use the arrow keys to nudge it around. Make a basic path: I use the bezier curve and straight line tool to rough out the outline. If you have no prior exposure to bezier curves you should probably play around for a while until you are comfortable with the tool and see what sorts of curve segments you can create. You may even want to google for a little bezier tutorial to get warmed up. Once you are ready start placing nodes. Click to place a node. Click and drag if you want to curve it right away. I usually make straight segments first and tweak the control points later. There probably is a proper method for placing nodes and it probably involves calculus and finding the inflection points of the curve, but I don't know this method. I start at the neck/body joint and place a node, place a node at the bottom of the cutout, tip of the horn, outside of the upper bout, the waist, lower bout, endpin and continue up the other side. In addition any sharp point will need a node. Click on the first node (it should turn red when you point at it) to close the path. It is ok if this is very rough. Nodes can be added, removed and moved as need be. Adjust the path: node tool. to curve. smooth round nodes (gives perfect beautiful curves). to corner + to line around neck. Borrow the path: Now that you have completed tweaking the path in Inkscape, let's borrow the path data for our use in Whibet UCP. open xml editor, select path, select "d" attribute, tripple click pathdata and copy to whibet ucp. enter the height of your drawing in the "Inkscape" box and click "From". I often round my pathdata off to the nearest 16th of an inch because I like round numbers and it is simple way to "compress" the path data. If you spent a long time drawing a perfect scale copy of a guitar, you probably don't want to do that because it will noticeable change your lines. Make PDF: If you are daring you can use Whibet to do various translating and scaling transformations to the body. for instance you may want to move the path up and to the right so that it is more centered in the print out. If not, you are done. enter the width and height of the path you drew in the viewbox boxes and click "Make PDF" to get a scaled printable version of all of your hard work. Closing: I'm sure there are many easier ways to get a printable guitar body template. Whibet UCP uses SVG and PDF paths in conjunction with FPDF and PHP. My plan is to someday add basic guitar plan generation to FretFind 2-D. If you would like to see this happen please drop me a line. Aaron Spike


			Home Compute Contact