Cinema 4D / BodyPaint 3D Program Documentation Tutorials Mechanical Modeling Tutorial Subdivision Surfaces Modeling A Working Example of Subdivision Surfaces Modeling
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Modeling the chair’s interior

If you want to start the tutorial at this stage, please click on the following link to access the .c4d file:

The chair’s inner lining will consist of two soft cushions. We will use the row of polygons above the centerline as a reference for the dividing line between the two cushions. At the top left of the image below the bottom half of the cushion has been selected.

In order to create the cushion we must first separate these polygons from the hemisphere to make a separate object. To do so, switch to Polygons mode and select the surfaces, as illustrated in the image below. Separate them from the hemisphere using the Split command from the menu Mesh | Commands. This will copy the selected polygons into a new object and the original object will remain unchanged. Now do the same to create the upper half of the cushion - refer to the image below for the correct selection.

Finally, select both new objects in the Object Manager and create a single object with them by selecting Connect Objects from the Mesh | Conversion menu. This way we will only have to deal with a single object instead of two. When objects are connected, overlying points or edges are not optimized but melted together. What impact this has when modifying the object using polygon tools will be described in subsequent steps. First, delete both objects with the separate cushion halves - these are no longer needed. Alternatively, once both objects have been selected, you can delete the original objects automatically by selecting the Connect Objects + Delete command (Mesh | Conversion).

Adding thickness to the padding

We will use the Extrude tool to add thickness to our padding objects, as we did with the chair’s outer shell. Before applying the Extrude effect, make the padding object a Child object of the chair’s outer shell. This will also make it a Child object of the Subdivision Surfaces, letting it automatically benefit from its smoothing effect. Again, switch to Polygons mode and make sure no polygons are selected before applying the Extrude tool. This time set the Subdivision value to 1, which will make the padding’s edge a little harder. Set the Offset value to 3. As you can see in the image below, the Extrude tool caused areas between the two previously separated surfaces to be constricted.

This is where the advantage of using the Connect command comes in - the points and edges of the two objects were not fused, allowing us to achieve this effect.

Shaping the outer edge

We want the padding to lie more snugly against the shell. The Subdivision Surfaces object’s attractive force on the padding object must be increased. We will use the same technique as we used for the outer shell. Switch to Edges mode and select the padding’s outer edge - one top and one bottom edge - using the Loop Selection tool (see image below). The outer shell has been turned off in the image to the selected edges can be better shown. Bevel the edges using the settings in the image below. Again, make sure the Subdivision is set to 0 to avoid generating too many polygons. At the right of the image is the result with an Offset of 0.2. In all, two contiguous selections must be created - one for the upper and one for the lower set of cushions.

The somewhat angular front edge where the two halves meet can use some improvement. We will use the Plane Cut to decrease the edges’ radii and increase their subdivision. In order to guide the Knife tool automatically, the padding object’s coordinate system (axis) should have the same orientation as its Parent object (the chair shell). Switch to Enable Axis mode and select Object mode in the Coordinates Manager. Now the padding object’s axial system will display Position and Rotation values relative to the chair shell. Set all Position and Rotation values to 0 in the Coordinate Manager and click on the Apply button to confirm your entries. The padding object’s axis will jump to the same position as the chair shell’s local axis and will also assume its orientation. Switch to Polygons mode. Select the Plane Cut tool and set its Mode to Plane. This will cause cut lines to automatically be placed parallel to the selected plane. Set the Plane option to X-Z and the Coords option to Local. Make sure the remaining parameters reflect the parameters in the image below. Also in the image below you will see where the cut line should be placed, and the well-rounded result. The closer the cut line is to the edge of the padding, the sharper the curvature between padding elements will be.

The padding’s inner surface

The padding’s inner surface needs to be made a little softer. We will achieve this look by increasing the distance between the edges and points. Switch to Polygons mode - the inner surface of the padding should already be selected, as pictured in the image below.

Use the Normal Move tool from the menu Mesh | Transform Tools to move the surfaces in the direction of their Normals. A Move value of 3 should be enough. Next, select the Normal Scale too from the same menu and enter a Scale value of 50%. This tool works differently from the normal Scale tool in that it scales the polygons in reference to their Normals and not according their axis. This will give the padding a much softer look, as you can see at the right of the image below. This completes the modeling stage for the chair’s inner padding.

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