Adobe Flash Professional CS5 : Manipulating Symbols in 3D Space (part 1) - Controlling the camera view: Perspective and vanishing point

The 3D Rotation tool and the 3D Translation tool are both found in the Tools panel just below the Free Transform tool. Settings for these tools can be accessed in the Transform panel when the 3D tools are active or a 3D symbol is selected in your Document window. If you haven't worked with 3D tools before, the various options can be a little disorienting at first, but with a little trial and error you will soon get your bearings.

To help you get started, I have included definitions for some of the terms you will come across when working with Flash symbols in 3D space:

• x-axis: Sets the position of the symbol in relation to the Stage, tracked from left to right. Rotating (transforming) a symbol around the x-axis is like flipping a Rolodex. Moving (translating) an object along the x-axis makes it appear closer to the left or right side of the Stage.

• y-axis: Sets the position of the symbol in relation to the Stage, tracked from top to bottom. Rotating a symbol around the y-axis is like turning a revolving door. Moving an object along the y-axis makes it appear closer to the top or bottom of the Stage.

• z-axis: Sets the position of the symbol in relation to the depth of the space. This is the third axis that was added to Flash CS5 to support transformation and rotation of symbols for (faux) 3D. Rotating an object around the z-axis is like spinning a bicycle tire or moving the hands of a clock, although the center point can be adjusted so it is not always in the middle of the symbol. Moving an object along the z-axis makes it appear larger (closer) or smaller (farther away).

• 3D Translation: Changing the location of a symbol in 3D space is called a translation. The 3D Translation tool provides handles for moving a symbol along the x, y, and z-axis individually.

• 3D Transformation: Rotating an object in 3D space is called a transformation. The 3D Rotation tool provides handles for rotating a symbol along the x, y, and z-axis individually or along the x and y-axis at the same time — for "free rotation."

• 3D Center point: By default, the 3D center point is usually the center point of the symbol, but by moving the 3D center point you can change the way 3D transformations (rotations) affect the symbol, in the same way that changing the center point for scaling or rotating an object in 2D space modifies the outcome of any changes.

• Global 3D space: This is the default setting for the 3D tools and means that any changes to location or rotation of a symbol are made in relation to the main Stage drawing area.

• Local 3D space: This is an alternative setting for the 3D tools (a toggle button at the bottom of the Tools panel appears when 3D tools are active), and it restricts changes to location or rotation of nested symbols to the drawing space of the container symbol.

1. Controlling the camera view: Perspective and vanishing point

There is only one camera view in the authoring environment for your Flash movie. The camera view consists of a perspective angle and a vanishing point: These global settings are available in the 3D Position and View section of the Properties panel when a symbol with 3-D translation or rotation is selected on the Stage. Changing the settings affects all 3-D symbols in your Flash movie but does not affect other elements.

The perspective angle sets the viewing "lens" for all of your 3D elements. The range of settings for perspective angle is from 1 degree to 180 degrees. The default perspective angle is 55 degrees to approximate a standard camera lens view. Think of the perspective angle setting as the zoom factor of your viewing lens. Smaller numbers move the view farther away and make 3D transformations less dramatic — they flatten the view. Larger numbers move the view closer and make 3D transformations more extreme — they emphasize any changes in the angle or rotation of an element. Figure 1 shows the same 3D Movie Clip (a rectangle with a 45-degree y-axis rotation), viewed with three different perspective angle settings.

Figure 1. Increasing the perspective angle setting "zooms" the view closer, making 3D transformations look more extreme. The same Movie Clip viewed with three different perspective angle settings (from L-R): 10 degrees, 50 degrees (the default setting), 120 degrees.

Another way to understand this feature is to compare it to our normal perception of objects in real space. If you are looking at a sculpture from a distance of 30 feet and you walk 10 steps to the left or right, your view does not change very much — you still see more or less the same side of the sculpture. However, if you are standing closer to a sculpture, say, 3 feet away, and you walk the same 10 steps to the right or left, your view changes dramatically.

The Vanishing point setting determines the endpoint of the z-axis and controls the direction that 3-D symbols travel if they are moved along their z-axis. Imagine it as an invisible anchor point in deep space that has a magnetic pull that makes all of your 3-D translations extend in its direction. In real space, the vanishing point is that place in your field of vision where parallel lines seem to come together. If you were looking down a road on a perfectly flat plain, it would be the spot where the road appeared narrower and narrower until finally it ended in a dot on the horizon — that dot is the location of the vanishing point.

By default, the vanishing point is set in the center of the Stage, but you can modify the setting at any time to a different x, y location — on or off the Stage. To view or set the vanishing point in the Properties panel, a 3-D symbol must be selected on the Stage. Figure 2 illustrates the result of a 45-degree x-axis rotation with vanishing points in different locations. Figure 3 illustrates how the vanishing point affects the direction that a 3-D symbol travels as it moves along the z-axis.

Figure 2. The location of the vanishing point determines the endpoint for the z-axis and the direction that objects recede into space. The same Movie Clip with a 3-D rotation viewed with three different vanishing point locations (from L-R): top-left corner of the Stage, center of the Stage (the default setting), and bottom right corner of the Stage.