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Splines are a Snap! Parts 1, 2, and 3


A gmax® B.A.T. Tutorial Part 1
Please PM STomnibus if you have any questions about this article.

Author: Larsz
Required: gmax®, the Maxis BAT gamepack
Recomended: Complete the gmax® Tutorials (in order to get familiar with the gmax® user interface)User Level: Beginner

Using Splines and Snaps together allows the user to create precision objects in gmax®. A Spline object is a very versatile object with many editing tools. Snaps make editing Splines easier. This tutorial explains how to use Splines and Snaps to create simple and compound objects. I would recommend completing the gmax® Tutorials that are available from discreet.com before beginning this tutorial.

Compound Splines Let's create a compound object made up of edited splines.

Some setup first. When you Start the B.A.T. you will see 4 Viewports; Top, Front, Left and Perspective.

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I am not sure why the B.A.T. starts zoomed so far out, or maybe it is just the way it starts for me but we want to work with meters and not tiles. To find out the distance between the gridlines, Left Click inside the Front Viewport to make it the active Viewport, and move your mouse to the 0,0,0 Point and then move the mouse to the first gridline to the right. Look at the value in the X Coordinate box. The value in the X Coordinate box indicates distance in meters from the 0,0,0 point. 16 meters is indicated by the first gridline in the picture below.

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Either use the Zoom Tool or scroll your scroll wheel on your mouse up to Zoom In until you see gridlines inside the Major Gridlines.

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We will be working in the Front Viewport to begin with. Make sure the Front Viewport is highlighted, then press the "w" key on your keyboard. "w" is the hotkey to toggle the active viewport from Minimum (4 viewports onscreen) to Maximum (Active viewport onscreen only).

Front Viewport Maximized
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We are now setup to begin.

Step 1. Create a Rectangle and an Arc.

Rectangle Setup
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Make sure the "Grid Points" snap is checked. I usually leave "Vertex" checked as well. To open the "Grid and Snap Settings" dialogue, Right Click the Snap button. To "Turn On" the snap, Hold the Left Mouse button on the Snap button and select "2.5".

Left Click + Drag the rectangle shape, Right Click to End the Rectangle Creation - I created a 3x3 Rectangle

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Arc Setup
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We are going to create the Arc using the Vertex Snap. Make sure that the Grid Points snap is not checked. The Rectangle shape has 4 Vertices (Vertex plural), one in each corner. We want to create an Arc that caps the Rectangle. To create an Arc shape, Left Click + Hold on the upper left Vertex of the Rectangle. When you hover the cursor near a Vertex you will notice how the Snap works. The Vertex you are near will have a Cross highlight.

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When the upper left Vertex is Snapped (highlighted), Left Click + Drag to the upper right Vertex. When you see the Snap, release the Left Mouse button.

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Your next Left Click will finish the Arc shape. Move your mouse to see how the Arc will change based on the final click. Notice how the Radius Value in the Parameters Roll-Out of the Arc changes as you move your mouse. Create your Arc with a 1.5 Radius like the image below.

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If you can't get the Radius to stop exactly at 1.5, get it as close as you can. Left Click in the Radius entry box and enter 1.5 for a value. As long as you haven't completed the Arc creation you can edit these values. To end the Arc creation, Right Click in the workspace.

The Rectangle and Arc have to be converted to Editable Splines. Select the Arc, Right Click, Select "Convert To.." and then select "Convert to Editable Spline" You will also have to convert the Rectangle to an Editable Spline using the same procedure. You will be converting a lot of shapes to an Editable Spline as you work with Splines. The only Spline shape that doesn't require conversion is the Line shape.

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1 Comments

Thank you.