Brush Clipping in SinEd - Part II by Eutectic
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1. Introduction
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Here, I'd like to cover a practical aspect of 2-point clipping. I feel that this is a necessary step before we can really appreciate the usefulness of 3-point clipping and the example used here will serve us well.
As mentionned at the end of Part I of this tutorial, one of the most interesting aspects of brush clipping is that it gives you ability to cut brushes in a way that lets you add faces to original shape or remove faces from it if you wish. For example, starting from a 6 faced cube or rectangle, you can easily clip it diagonally down the middle to create a 5 faced wedge shape thus effectively removing a face. If you clip that wedge yet again, you can obtain a 4 faced pyramid.
In the following example, we will do the opposite: we will start from a cube and add faces to it.
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2. Making an octagon from a cube
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Let's create a octagonal shaped brush from a cube. Those are often used in 3D maps to make cylindrical type shapes like pipes and are generally very useful shapes to simulate anything that's round shaped. Let's start from the same 128 x 128 x 128 cube we used in Part I of the tutorial.
First, go to the 2D XY view (top view), select the brush and enter your first pair of clip points (Shift-RightClick) while observing the clockwise rule as illustrated below:
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Figure 1b: Drawing the first pair of clip points in clockwise order.
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Hit ENTER. Your first clip is done and your brush now has an extra face (7 instead of 6). Below is a 3D graphical representation of the angled clipping plane at work:
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Figure 2b: The angled clipping plane at work - 3D view.
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Now just repeat the operation for the remaining 3 corners of the brush always going clockwise. A new face will be created at each operation:
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Figure 3b: Drawing the second pair of clip points in clockwise order.
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8 faces ...
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Figure 4b: Drawing the third pair of clip points in clockwise order.
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9 faces ...
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Figure 5b: Drawing the fourth pair of clip points in clockwise order.
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And 10 faces. Here's the result in the 3D view, a cool octagonal shape:
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Figure 6b: The resulting octagonal brush - 3D view.
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You will notice that I made all my cuts at 45 degree angles. I did this because those are the easiest angles to keep track of in the 2D views and this simplifies things a lot for what will come later.
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3. Making a tapered end
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What would be nice now is if we could taper the top end of the cylinder to make a shape that could be used for the base of a round column for example. In order to do this, we will have to clip the brush some more in order to add 8 more faces to it. Since this has to be done in the side views, let's first start by switching to the XZ view and clip the left and right sides:
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Figure 7b: Clipping the left side - 2D XZ view.
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And here again is a 3D representation of the clipping plane at work:
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Figure 8b: The clipping plane at work - 3D view.
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Now let's do the right side:
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Figure 9b: Clipping the right side - 2D XZ view.
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In order to do the other 2 sides of the brush, we now have to switch to the other side view: the YZ view. Let's do that now and clip the left side first:
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Figure 10b: Clipping the left side - 2D YZ view.
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And another quick look at a 3D representation of the clipping plane at work to make it easier to see what we're doing at this point:
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Figure 11b: The clipping plane at work - 3D view.
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And the right side:
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Figure 12b: Clipping the right side - 2D YZ view.
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And the result in the 3D view, a somewhat weird looking shape at this point:
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Figure 13b: The resulting brush - 3D view.
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Ok, all we have to do now is clip the remaining 4 angled sides. If you observe the shape of the brush above, you can see that each of those sides need to be angled 45 degrees horizontally AND 45 degrees vertically so our clipping plane has to be angled the same way to make the desired cuts.
But since all the 2D views are orthogonal, they only allow you to orient a clipping plane in one angle at a time. So what 2D view can we use to clip those faces? You can't rotate your 2D view in SinEd and there's no such thing as a "halfX-halfY-Z view" right? So we're basically stuck at this point and can't make our cuts. Is there any way we can do this?
TADA!! Yes, there is! By using 3-point clipping. This is the feature that can solve this problem. But in order to use it, we first have to learn how it works. On to Part III...
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