the sweater tutorial

The Sweater

In this tutorial, we'll explore a few ways to make comfortable looking sweaters, pants, socks etc... Look at the end of this tutorial to see how to view these models over the web in full 3D. click here

Let's start by launching Amapi and building a cube. The idea with this is to to start from a very simple basic shape and gradually add complexity to it.

After inserting the cube, we'll want to extrude

the arms and

a crew neck, and

a trench coat bottom.

Select the Extrusion tool. Yes, you can extrude individual facets off a volume or surface, i.e. it doesn't have to be a curve you use for a section. This lets you 'grow' additional branches. Note that you can also do this with the Sweep tool.

Modeling in Amapi is fast and fun if you use both hands. If your right hand holds the mouse, try to keep the left hand on the arrow keys as much as possible. This will quickly make you feel like you're holding the object you're designing in your left hand while using the right hand to grab a tool, chisel away, drop the tool, do more modeling with other tools etc...
Use the Arrow keys to orbit the workspace camera a little bit to the right side so you can see the right side of the cube, then click on that side. This starts the extrusion of that facet, as you move the cursor to the right.

First, we'll move a little bit to the right to indicate where we want the shoulder area to be placed. Click once.
Keep moving.

Click again a little further, to indicate where the elbow area will be.

Finally, move even further and click again for the final extrusion, to indicate where the hand area will be.
Hit ENTER (Return) to finish the extrusion.

Hit Enter again to do a quick Rendering. Notice that the hand opening is still closed. The whole thing started as a volume. It still is a volume. You can verify that easily - just double-click the part, or click the question mark in the lower right corner for object information.
Note that by default, Amapi attempts to show a smooth appearance at rendering, because the threshold angle for smoothing is set to around 40 degrees. You can set it to zero in the Render Settings dialog if you want a flat shaded look.

Also, in the View menu, select New View, then Free View, and you'll be able to see your work in progress in a shaded mode. This popup view window can be moved to a second screen if you have a Mac or PC with dual screens. It is rendered through OpenGL, so the better your opengl card's driver and Zbuffer depth the better the visual result. I like to use the Wireshade mode in such view, i.e. smooth shaded with wireframe overlay, to get an idea of the mesh density.

Now, let's get on with modeling. We'll extrude the top in a similar way, to create a crew neck in several steps.
Hit ENTER when done extruding the top facet for the crew neck area.

Finally, use the arrow keys to rotate to a more frontal look and a little bit from below, and extrude the bottom facet of the cube, to create a trench coat look.

After completing this, Hit Enter to do another quick Rendering.
You could do another extrusion at this point for the remaining other arm section. Or, if you want to ensure that the left and right half are identical and the whole thing be symetric, you can use this approach:

cut the part along the middle line in two

remove the left part

mirror the right part

weld the two halves together.

We'll use this approach, just for grins. In case you want to continue with my model, here it is. (Click Right (PC) or Click-and-Hold (Mac) and select "Save Target As..." or "Save Link As..." (depending on browser).)

Use a front view. Perhaps even better, switch from Perspective to Orthographic view (lower left on control panel.

the Modeling toolkit, select the Punch tool. This is Amapi's boolean operator. You can use it in different ways. One common way is to use it between two parts. In this case though, we'll use it on one part and draw a cutting line across from top to bottom to slice the object in two parts.

Click the same object again, to indicate that you'd like to draw a cutting profile. (like a cookie cutter). Note that you could just as easily draw the profile as a 2D curve first and select it at this time.
Click somewhere above the neck in the head area, to start drawing the curve. It will need only one more point, i.e.e it will be a straight line from top to bottom.

Since we want a perfectly vertical line, just hit the SPACEBAR to toggle between the axes. Hit SPACEBAR a second time to show just the vertical (green) 'Y' axis.
Then click below the trenchcoat bottom area. The object gets split (cut) into two parts.

Click to select the left portion, and hit the Delete key to delete the part, or the Hide tool (dark ghost at center bottom control panel) to hide it as we don't need that part anymore.
Return back to Perspective mode and use the arrow keys to inspect it.
It appears that the whole thing is still a solid, with no openings for head, legs, hands, etc...
When you cut across a volume, the resulting parts remain volumes (closed solids).

Use the 'Delete Faces' tool to click and delete the required opening at the top (neck), the right side (hand opeining) and the bottom (waist area), and also the left side where the other mirror copy half will be needed. We don't want to have a polygon in the middle there.
Hit Enter to finish this deletion process.

In the assembly toolkit, select the Mirror 3D tool.
A bounding box will appear.

Select the left side of the box, and the mirror copy of the part appears.
Swipe the tool away or hit Enter to finish.
Note that these are still two separate parts. You can use the +/- keys to select and cycle through all parts (2 parts in this scene). Or you can simply click and select the left or right half.

Use the Weld tool to weld (glue) the two parts into a single topology.
When you select the Weld tool from the assembly toolkit, you get to click a region, which we call 'throwing the lasso'. Make sure at least one vertex of each desired part (each half) is in the selection.

Here's the part (phase2.a3d) I created so far (Save As...)

We can now use various modeling and vertex editing tools to fine-tune and edit the shape.
Use the Stretch tool to move individual vertices around while the arrow keys let you orient the camera so you look top-dwon or from the side etc...
Use the Delete faces tool again to open the neck area and place a zipper there. However, if you need more details in that area, use the Tesselate tool to add a few polygons right there.

Then use the Delete Faces tool to remove the inner 4 small squares.
Notice how Amapi highlights in dark violet the existing openings, and in red the new ones as you click.

You can now use the Weld tool again to weld multiple points together into a single vertex. Yes indeed, the weld tool has multiple uses - either to weld multiple parts into one, or to weld multiple points into one. Just make sure you get a clean shot which doesn't include other vertices which are in the back.

Click here (Save As...) to load the model we have made so far. (phase3.a3d)

Now, let's see how we can make some cool wrinkles, especially in the elbow area.
One of my favorite tools for this is the Chamfert tool, which traditionally is used to create filets (bevels), but in this case simply will assist in creating a few more polygons all around the perimeter of the elbow, or shoulder area too.
Throw the lasso over the 4 edges making the elbow section on the right side. Hit Enter when done.

Click right (Option-click on Mac) to to switch to a different mode of selection, where you can select edges individually by clicking them. Or, use the left-most icon in the chamfert tool
Click the 4 edges making the section around the shoulder.

By default, only the start and end of the chamfert region (bevel) are shown. If you want to see the full mesh, click the right-most icon.

To increase the distance (radius) of the bevels, use the +/- keys.
Hit Enter when done.

Now, let's use the STretch tool again
Move every other vertex on the beveled area a little bit up. Move the others down. You can right-click (option click) or select the bulls-eye cursor to select a bunch of vertices to move all together.

After a little bit more work, you could get to something like this.
Click this model here (phase4.a3d) to view it (Save As...)

Now comes the final magic trick - making it look organic, smooth.
Simply use the Smooth tool.
There are 5 smoothing methods in Amapi 5.15 (only 1 in Amapi 4.15). The left-most icon (default smoothing method) is for Bezier, which can overshoot. The next two methods (Doo-Sabin and Catmull) create easily excellent results.

Hit Enter to see the final mesh, to just swipe away. Before that, you can use the +/- keys to increase or decrease the subdivision count.
Hit Enter again and you'll see the shaded rendering of the smoothed surface. Make sure you set the Autosmooth angle back to around 35 - 40 degrees in the Render Settings, or else you'll be looking at lots of flat shaded polygons.

After about 20 more minutes of fiddling with the vertices, and trying various smoothing methods, here's one that looks just great.
Here's the coarse model again.
Saves As... sweater.a3d

And here are the 5 different smoothed results. Click the icons for a larger image.

What to do with the model?

Here are some ways to use the Cartoon shaders of Amapi:

And here's a rendering done in Carrara after exporting from Amapi 5.15 to RayDream Studio 5 format.

click for large image

New! Finally, here's a look at viewing the model over the web in full 3D, using TGS 3Space technology

Click here

Let's start by launching Amapi and building a cube. The idea with this is to to start from a very simple basic shape and gradually add complexity to it.
After inserting the cube, we'll want to extrude the arms and a crew neck, and a trench coat bottom.
Select the Extrusion tool. Yes, you can extrude individual facets off a volume or surface, i.e. it doesn't have to be a curve you use for a section. This lets you 'grow' additional branches. Note that you can also do this with the Sweep tool.
Modeling in Amapi is fast and fun if you use both hands. If your right hand holds the mouse, try to keep the left hand on the arrow keys as much as possible. This will quickly make you feel like you're holding the object you're designing in your left hand while using the right hand to grab a tool, chisel away, drop the tool, do more modeling with other tools etc... Use the Arrow keys to orbit the workspace camera a little bit to the right side so you can see the right side of the cube, then click on that side. This starts the extrusion of that facet, as you move the cursor to the right.
First, we'll move a little bit to the right to indicate where we want the shoulder area to be placed. Click once. Keep moving.
Click again a little further, to indicate where the elbow area will be.
Finally, move even further and click again for the final extrusion, to indicate where the hand area will be. Hit ENTER (Return) to finish the extrusion.
Hit Enter again to do a quick Rendering. Notice that the hand opening is still closed. The whole thing started as a volume. It still is a volume. You can verify that easily - just double-click the part, or click the question mark in the lower right corner for object information. Note that by default, Amapi attempts to show a smooth appearance at rendering, because the threshold angle for smoothing is set to around 40 degrees. You can set it to zero in the Render Settings dialog if you want a flat shaded look.
Also, in the View menu, select New View, then Free View, and you'll be able to see your work in progress in a shaded mode. This popup view window can be moved to a second screen if you have a Mac or PC with dual screens. It is rendered through OpenGL, so the better your opengl card's driver and Zbuffer depth the better the visual result. I like to use the Wireshade mode in such view, i.e. smooth shaded with wireframe overlay, to get an idea of the mesh density.
Now, let's get on with modeling. We'll extrude the top in a similar way, to create a crew neck in several steps. Hit ENTER when done extruding the top facet for the crew neck area.
Finally, use the arrow keys to rotate to a more frontal look and a little bit from below, and extrude the bottom facet of the cube, to create a trench coat look.
After completing this, Hit Enter to do another quick Rendering. You could do another extrusion at this point for the remaining other arm section. Or, if you want to ensure that the left and right half are identical and the whole thing be symetric, you can use this approach: cut the part along the middle line in two remove the left part mirror the right part weld the two halves together. We'll use this approach, just for grins. In case you want to continue with my model, here it is. (Click Right (PC) or Click-and-Hold (Mac) and select "Save Target As..." or "Save Link As..." (depending on browser).)
Use a front view. Perhaps even better, switch from Perspective to Orthographic view (lower left on control panel.
the Modeling toolkit, select the Punch tool. This is Amapi's boolean operator. You can use it in different ways. One common way is to use it between two parts. In this case though, we'll use it on one part and draw a cutting line across from top to bottom to slice the object in two parts.
Click the same object again, to indicate that you'd like to draw a cutting profile. (like a cookie cutter). Note that you could just as easily draw the profile as a 2D curve first and select it at this time. Click somewhere above the neck in the head area, to start drawing the curve. It will need only one more point, i.e.e it will be a straight line from top to bottom.
Since we want a perfectly vertical line, just hit the SPACEBAR to toggle between the axes. Hit SPACEBAR a second time to show just the vertical (green) 'Y' axis. Then click below the trenchcoat bottom area. The object gets split (cut) into two parts.
Click to select the left portion, and hit the Delete key to delete the part, or the Hide tool (dark ghost at center bottom control panel) to hide it as we don't need that part anymore. Return back to Perspective mode and use the arrow keys to inspect it. It appears that the whole thing is still a solid, with no openings for head, legs, hands, etc... When you cut across a volume, the resulting parts remain volumes (closed solids).
Use the 'Delete Faces' tool to click and delete the required opening at the top (neck), the right side (hand opeining) and the bottom (waist area), and also the left side where the other mirror copy half will be needed. We don't want to have a polygon in the middle there. Hit Enter to finish this deletion process.
In the assembly toolkit, select the Mirror 3D tool. A bounding box will appear.
Select the left side of the box, and the mirror copy of the part appears. Swipe the tool away or hit Enter to finish. Note that these are still two separate parts. You can use the +/- keys to select and cycle through all parts (2 parts in this scene). Or you can simply click and select the left or right half.
Use the Weld tool to weld (glue) the two parts into a single topology. When you select the Weld tool from the assembly toolkit, you get to click a region, which we call 'throwing the lasso'. Make sure at least one vertex of each desired part (each half) is in the selection.
Here's the part (phase2.a3d) I created so far (Save As...)
We can now use various modeling and vertex editing tools to fine-tune and edit the shape. Use the Stretch tool to move individual vertices around while the arrow keys let you orient the camera so you look top-dwon or from the side etc... Use the Delete faces tool again to open the neck area and place a zipper there. However, if you need more details in that area, use the Tesselate tool to add a few polygons right there.
Then use the Delete Faces tool to remove the inner 4 small squares. Notice how Amapi highlights in dark violet the existing openings, and in red the new ones as you click.
You can now use the Weld tool again to weld multiple points together into a single vertex. Yes indeed, the weld tool has multiple uses - either to weld multiple parts into one, or to weld multiple points into one. Just make sure you get a clean shot which doesn't include other vertices which are in the back.
Click here (Save As...) to load the model we have made so far. (phase3.a3d)
Now, let's see how we can make some cool wrinkles, especially in the elbow area. One of my favorite tools for this is the Chamfert tool, which traditionally is used to create filets (bevels), but in this case simply will assist in creating a few more polygons all around the perimeter of the elbow, or shoulder area too. Throw the lasso over the 4 edges making the elbow section on the right side. Hit Enter when done.
Click right (Option-click on Mac) to to switch to a different mode of selection, where you can select edges individually by clicking them. Or, use the left-most icon in the chamfert tool Click the 4 edges making the section around the shoulder.
By default, only the start and end of the chamfert region (bevel) are shown. If you want to see the full mesh, click the right-most icon.
To increase the distance (radius) of the bevels, use the +/- keys. Hit Enter when done.
Now, let's use the STretch tool again Move every other vertex on the beveled area a little bit up. Move the others down. You can right-click (option click) or select the bulls-eye cursor to select a bunch of vertices to move all together.
After a little bit more work, you could get to something like this. Click this model here (phase4.a3d) to view it (Save As...)
Now comes the final magic trick - making it look organic, smooth. Simply use the Smooth tool. There are 5 smoothing methods in Amapi 5.15 (only 1 in Amapi 4.15). The left-most icon (default smoothing method) is for Bezier, which can overshoot. The next two methods (Doo-Sabin and Catmull) create easily excellent results.
Hit Enter to see the final mesh, to just swipe away. Before that, you can use the +/- keys to increase or decrease the subdivision count. Hit Enter again and you'll see the shaded rendering of the smoothed surface. Make sure you set the Autosmooth angle back to around 35 - 40 degrees in the Render Settings, or else you'll be looking at lots of flat shaded polygons.
After about 20 more minutes of fiddling with the vertices, and trying various smoothing methods, here's one that looks just great. Here's the coarse model again. Saves As... sweater.a3d
And here are the 5 different smoothed results. Click the icons for a larger image.