Teach Yourself
CorelDRAW 8 in 24 Hours
In this hour, you look at how to create your own objects using the Free Form Modeling tool, apply shader properties to objects, set and change light properties, and look more closely at some of the rendering options and rendering properties to create more realistic looking scenes.
The Free Form Modeling tool (see Figure 24.1) is used like all the other object creation tools. Drag in the Perspective window to create a bounding box and release the mouse button. Dream 3D launches you into the Free Form Modeling window that replaces the Perspective window. The first thing that appears is a dialog box requesting the name of the new object you are about to create.
In the Free Form Modeling window, you create an object by defining its cross sections and the way in which Dream should extrude, connect, or sweep these cross sections.
Free Form Modeling window.
Just A Minute: To extrude means to take a cross section and to stretch the object out of the cross section. For example, when a circle is extruded, it forms a cylinder.
In Dream 3D, a free form modeled object can also contain multiple cross sections. These cross sections can be different shapes and sizes, and you can specify how these cross sections connect. This is called skinning. Dream 3D has two types of skins: shape-to-shape and point-to-point. Shape-to-shape creates smooth surfaces between the different cross sections. Point-to-point skinning is used between similar cross sections, and the connection is made on a vertex-to-vertex basis. This creates very sharp edges.
To sweep a cross section in Dream 3D is to create an object by extruding it in a spiral or circular manner. For example, a circle swept in a circular path creates a torus or donut shape.
The best way to model an object is to look at the object and break it down into parts. The parts must be parts that can be made either with prebuilt primitive objects or objects created using the Free Form tool.
When you enter the Free Form Modeling window, you discover that a couple of things change. The first is that the Perspective window changes. The view that you have is similar in that it contains some grid planes that you can use as references for your object.
An additional plane, which is currently selected (colored blue), is parallel to the x-plane. This is the drawing plane. It is on this plane that you draw vector objects that will be extruded (pulled out) outward along the y-plane and the bottom plane. The object is pulled out and stretched along the magenta lines, called sweep paths, which are found on these planes.
The currently selected plane is blue. Click on a plane to select it. Then choose View | Type | Drawing plane. The currently selected plane is the drawing plane, and the Modeling window changes to view the selected plane face-on. To begin, click on the back plane to view the default drawing plane, and type Control-5, which is the keyboard shortcut for viewing the currently selected plane.
Just A Minute: Just as in the Perspective window, you can change your view on the object that you are modeling. To view an object from the left, for example, select View |Type | Left.
Let's begin by drawing a square on the drawing plane. To draw any vector shape on the plane is very similar to using CorelDRAW.
Rectangle.
Extruded rectangle.
An extruded rectangle is not much different than a squashed cube, so try something a bit different. This time combine two squares together to make a frame-like object for Dream 3D to extrude.
You can use all the drawing tools found in the toolbar. The Polygon tool, for example, asks for the number of sides of the polygon and then draws an equally sided polygon. A polygon with different length sides can be created using the Bézier Tool. Instead of dragging a node when creating your curve, simply click the node into existence, and then move your cursor and click again. A straight line connects the new nodes. You can convert these nodes to have Bézier handles by using the Convert Node tool.
Combined rectangles create a hollow cube.
Just A Minute: To delete a shape, simply select the Selection tool and click on the edge of the object you want to delete. Then press Delete.
You can also draw Bézier curves to create odd shapes.
You can modify a Bézier curve by using the Selection tool. You can select and then drag nodes to a different position. You can also drag the node's Bézier handles to change the curvature of a curve. Experiment with drawing Bézier curves and modifying their nodes. To convert a regular node to a Bézier node, select the Convert Node tool, and drag the node to make its Bézier handles appear.
The kinds of objects that can be created using this technique are almost limitless. Extruding cross sections using the Free Form Modeling tool can create a vast variety of objects. To import a cross section from CorelDRAW, select File | Import, and using the dialog box, enter the filename of the Draw file to import. After you import the CorelDRAW drawing, you can marquee select the entire cross section. Then select Geometry | Scale and enter a scale value for both the horizontal and vertical axes.
Just A Minute: Note that not all CorelDRAW shapes are ideal for extrusion. Sometimes, Dream 3D has problems extruding complex (and even simple) curves into three-dimensional objects. The result can often be an object with a piece missing. If you view the drawing plane face-on and import a curve from CorelDRAW, you can see a problem in the curve if no red appears where you would expect red to appear. No silver bullet exists for fixing these kinds of extrusions, but a certain amount of moving and tweaking of the curve can alleviate, at times, the entire problem.
Notice that an object is extruded only up to the end of the magenta lines, the sweep paths. These lines can be stretched to increase the depth of the extrusion. If you extend one sweep path, it affects the other, so it doesn't matter which one you extend. Figure 24.5 extends the y-plane sweep path to extrude your object further. Note that you can extend the sweep path both forward and backward and past the edge of the plane. To constrain the path as you move the node, press Shift while dragging the node.
Notice also that the sweep path does not have to be straight. That is, you can modify the path to bend, and the extrusion of your cross section proceeds along the curve. Try this: select the Selection tool and click on the end point of one of the sweep paths. Then select the Convert Point tool, and convert that endpoint into a Bézier point. Using the Selection tool again, drag the Bézier handles of this point to cause the sweep path to bend (see Figure 24.6).
Any Bézier-type effects can be applied to the sweep path. You can add another point and modify the curvature of the sweep path further. Notice that Figure 24.6 added an extra node and bent the path into a sinus wave, creating an interesting three-dimensional object.
Extending the sweep path.
Bending the sweep path.
You have two sweep paths (one on the y-plane and the other on the bottom plane). The changes to a sweep path apply only to that particular sweep path, but you can make changes to the other sweep path that applies to the other plane (see Figure 24.7).
Bending the sweep path in both planes.
All your extrusions, by default, have been straight (except when you modify your sweep path to bend). Two other extrusion methods that you can apply to a model are in the Modeling window. The first is the spiral and the second is the torus.
The spiral extrusion extrudes a cross section along a spiral sweep path. Create a cross section on the drawing plane. Select Geometry | Extrusion Preset | Spiral and a dialog box appears. Experiment with the spiral dialog box settings (notice the Help box in the dialog box).
The torus setting creates a donut shape extrusion. Thus if you extrude a circle with the Extrusion Preset of Torus at the default radius of 8 inches, the result is a donut.
The Torus Extrusion Preset is also useful for lathing. Lathing an object is like using a real lathe, the difference is that you create the cross section of the object on the drawing plane using the Bézier curve and tell Dream 3D to spin that object around its center.
An object has a cross section that is extruded along a sweep path, but it also has another setting that can change the shape of an object, called an envelope. An envelope is parallel to the sweep path and defines the outside of the object. Just as the sweep path can be modified using the Bézier tools, so too can the object's envelope. An object's envelope paths are the blue lines in Figure 24.8. Selecting Geometry | Extrusion Envelope | Symmetrical produces four envelope paths, one for each side of the object.
Extrusion envelopes.
The four settings for the envelope type are None, Symmetrical, Symmetrical in Plane, or Free. The Symmetrical envelope means that what you do to one envelope path is applied to all the other paths. The Symmetrical in Plane envelope means that what you do to one path on one plane will be applied to that path and the other path in the same plane. Lastly, the Free envelope enables you to modify each path separately. Figure 24.9 shows an example of a modified envelope.
An object created using modified envelope paths.
If you add points to the sweep path using the Add Node tool, you can create an extra cross section for the object at that point. You can also create extra cross sections in your object (equally spaced) by selecting Cross-Section | Create or Create Multiple.
Once a cross section is created, select a specific cross section to work on by using the Selection tool. Then modify the cross section by moving the object, moving its object handles, modifying its Bézier curves, and so on. The modifications affect the current cross section and affect how the extrusion proceeds from one cross section to the next.
In reality, objects have properties that make them look real. Properties such as color, reflec-tivity, transparency, and so on can be applied to an object using shaders. A set of predefined shaders comes with Dream 3D, but you can also create your own customized shaders. Again, the key to working with shaders is to experiment.
Apply a predefined shader to an existing object. Create a cube and center it in your world. Ensure that the Shaders Browser window is visible. If it is not visible, then select Window | Shaders Browser.
Spheres represent all the shaders. To color your red cube, for example, with a blue color, select the cube and then select the blue sphere in the third row. A black square will surround the currently selected shader. Select Apply in the bottom-left corner of the Shaders Browser window to apply the shader to the currently selected object. The cube turns blue.
Show the production frame (choose View | Production Frame) and position the cube so that it fits into the production frame. Then press Control+R to render the scene using the default values (see Figure 24.10).
To create a new shader, select a currently existing shader and select Shader | Duplicate in the Shaders Browser menu or select Shaders | New. Scroll down in the Shaders Browser to find your newly duplicated shader.
Notice that the Apply button in the bottom-left corner of the Shader Browser window has a flyout menu associated with it. Click and hold on the Apply button. Two options appear: Apply Non-Empty Channels and Apply All Channels.
A rendered blue cube.
Channels in Dream 3D are those individual properties that you can apply to an object. The eight channels that can be assigned different values (and some that can be assigned other shaders) are color, highlight, shininess, bump, reflection, transparency, refraction, and glow. If you select Apply Non-Empty Channels, then Dream will only apply those channels to the objects that are not empty.
The object has a shader that consists of all the channels that have ever been applied to the object. This shader does not exist separately in the Shaders Browser window, but it can be applied to other objects.
To view an object's shader use the Shader Eye Dropper tool. Select the Shader Eye Dropper tool and click on the cube. The result is a shader that is loaded and displayed in the Shader Editor window (see Figure 24.11).
To apply one object's shader to another object, select the second object, and using the Shader Eye Dropper tool, click on the first object and select apply.
You can also double-click on any shader in the Shaders Browser window to load a shader into the Shader Editor. Shaders modified in the Shaders browser can be saved along with the other shaders by selecting Files | Save all.
Once in the Shader Editor, you can select a channel and modify its values. It is usually a good idea to expand the Shader Editor window so that you can see all the options available.
Shader Editor displaying channels for the current object. This is the maximized view of the Shader Editor.
Each channel can have a different kind of setting. Select Type from the Shader Editor window menu. Notice a number of different types you can assign to a channel: composite, global mix, value, color, Texture Map, operators, pattern functions, natural functions.
To learn more about channels and the values that can be set, look at the shaders that make up the objects that come in the object browser. Drag the object from the object browser into the Perspective window and use the Shader Eye Dropper tool to look at the object's shader channels. Also, double-click on a shader in the Shaders browser to load it into the Shader Editor and view the channels that make up these channels.
If you have a shader in the Shader Editor, you can apply that shader to the currently selected object by selecting Apply in the bottom-left corner of the Shader Editor.
The color channel changes the underlying color of the object. If you select Type | Color, you can select a color to apply to your object by double-clicking on the color swatch in the Shader Editor. A Color dialog box appears in which you can select a color by entering its R, G, and B values. Or you can also click on the color wheel in the top-right corner to display an enhanced color dialog box. Selecting Type | Value selects a grayscale value for the object.
Selecting Type | Texture Map applies an image that you can load into the shader color channel (see Figure 24.12). When you select Texture Map, Dream 3D asks for the filename of the image. Select the image type from the Files of Type drop-down list and browse around until you find the image that you want to apply to your object. If your image is not oriented correctly, press on one of the arrows to rotate or flip the image. If you want to select a different image, select the Floppy Disk icon and load a new image into the shader. You might also tile the image by checking the Tile box and selecting the number of times the image will tile on the object. The White is Invisible check box makes any white pixels disappear.
Selecting a Texture Map for a channel.
To remove all channel attributes, select the Channel tab and press Delete.
In the Shader Editor, select View | Flat Preview to preview your shader as flat instead of as a sphere.
You can change the way a shader is applied to your object by right-clicking on the object and selecting Properties. In the Object Properties dialog box, select the Shaders tab.
By default, Dream applies parametric mapping of your shader to your object. Simply put, this means that Dream wraps the shader all around your object by stretching the image if necessary. Of course, the type of mapping does not necessarily matter if all you have is a color shader, but the moment your shader includes a Texture Map in any of the channels, it matters how the image is mapped to your object.
Shaders can also be combined in a channel by using the Operator functions mix, add, subtract, and multiply. An operator function applies to two shaders, and if using mix, applies a pattern or natural function. See the following figures (24.13, 24.14, and 24.15) for examples.
Add operator using two shaders in the Transparency channel.
Multiply operator on two shaders in the Transparency channel.
A set of channel types simulate, mathematically, patterns and natural functions. Pattern functions consist of checkers and wires. Natural functions are wood, spots, and marble. Each of these functions have a set of parameters that define the function. Experiment with these functions and their values. Remember that you can apply these functions to any channel and that you can also mix these functions together with other functions and/or shaders to create an amazing variety of shaders. The trick is to experiment. Figure 24.16 is an example of the wood natural function in the bump channel. The Bump channel uses the grayscale values of the wood function to determine how bumpy the surface of the object will be.
Subtract operator on two shaders in the Transparency channel.
Bump consists of checkers and wires. Natural functions channel using the natural wood function.
Not only can a shader be applied to the entire object, but you can also create a shader (or use an existing one) to paint a patch onto an object. The Paint Rectangular Shape tool (and the other paint shape tools in the flyout) can paint a shape onto the surface of an object. Select a shader and then the Paint Rectangular Shape tool. Drag the shape on the surface of the object. If the shape is not quite right, select the Paint Shape Selection tool (in the Selection tool flyout) and drag the patch to move it or its control handles to resize it (see Figure 24.17).
Using the Paint Shape tools with a shader.
Notice that the paint shape will conform to the shape of the object. There will be times when the paint shape does not fit the object as you would like, and no matter what you do, the shape will not behave as you want. To fix this, you can switch to a different mapping mode for the object. Remember that Dream applies a shader by mapping the shader to the object based on the currently selected mapping mode for the object. This mapping mode also affects how a paint shape conforms to the object.
You can also paint with a paintbrush on the surface of an object using the 3D Paint Brush tool (see Figure 24.18). When you select the 3D Paint Brush, a Brush dialog box appears in which you can modify the brush shape and size (and other options). In order to use the 3D Paint Brush tool, you need to be in the Better Quality view. If you are not in this view, Dream asks you if you want to switch to this mode.
To delete a painted shape or paintbrush stroke from an object, use the Paint Shape Select tool to select the shape and press Delete. If the Shader Editor is open for the object, the editor loads the shader of the shape when you select the shape. In this way, you can make sure that the shape you selected is the shape that you want to delete.
Using the 3D Paint Brush tool to paint graffiti on an object.
The following are a set of effects that are only visible when your scene is rendered. To change these effects, select Scene and any one of the following: ambient, atmosphere, Reflected background, backdrop, and filters. The result is the Render Effects dialog box. Click on the desired effect tab and modify its parameters to create the effect.
The Ambient effect, for example, sets the ambient light of the scene (light that appears equally everywhere). The Reflected background tab creates a background to your scene that reflects from objects within the scene (if they have any reflection values in their reflectivity channel). The Backdrop effect, however, only exists in the background and does not interact with the objects in the scene. You have many options for these effects; play and experiment with these settings and remember that they become visible only when you render your final scene.
To add lights, use the Create Light tool and drag in the Perspective window. The lights Object Properties dialog box appears. A light is similar to other objects in Dream 3D. You can position, rotate, and change the lights properties.
A number of different kinds of lights include spot light, distant light, and bulb light. Each of these lights has different properties, such as brightness, color, and so on.
The spot light acts like a real directional spotlight. You can modify its half angle (how wide the spot light is), its angular fall off (whether or not the light is sharp on the edges of the spot light), its distance fall off (how quickly it loses intensity as objects get further away from it), and so on.
The distant light is like a giant lightbulb placed at a great distance, sort of like the effect you get from the sun (where the light beams are parallel to each other). A distance light cannot be modified like the other light objects, but you can place a distant light relative to the entire scene by positioning the circle on the sphere. To position the light behind the scene, choose the Back radio button. To edit a distant light's properties, select the light in the Hierarchy window, as you cannot select it in the Perspective window.
A light can also shine through a blind, gradient, or map. The Gel tab in a light Object Property dialog box sets the kind of gel that the light shines through. This can create effects such as lights behind venetian blinds.
A grayscale image map can be used as a gel to simulate a light behind an object, such as a tree for example. Use PHOTO-PAINT to create the tree map by painting black on a white background; then select the Gel tab and select Map type.
To change the properties of a light, you can double-click on the light. Or select the light, right-click, and choose Properties.
You can reposition your view on the scene by moving a camera or by creating a new camera and rendering your scene through this new camera. You can save camera positions for easy retrieval of predefined camera positions.
To move the camera, select Scene | Camera Settings to display the Camera Properties dialog box (see Figure 24.19). In the Camera Properties dialog box are three tools for repositioning the camera: Camera Dolly, Camera Pan, and Camera Track tools. These tools are also accessible from the toolbox. Select one of these tools and drag on the window to see its effect on the current camera position. Note also a small triangle in the bottom-left corner of the Camera Properties dialog box that shows an expanded view of the dialog box and reveals more camera controls. Play with these controls to see the change in the camera angle and position. Notice the small Scale icon that enables you to change the amount the camera moves each time one of the camera position controls is selected.
Just A Minute: The Dolly tool rotates the camera around your scene while keeping the camera pointed at the same spot in your scene. If you have an object selected, the camera moves centered on that object. If no object is selected, the camera is pointed at the center of the universe.
The Pan tool rotates the camera on its own axis. This is similar to a camera on a tripod where the camera is rotated and moved, but only at the point where the camera attaches to the tripod.
The Track tool moves the camera up, down, left, or right on a plane where the camera exists.
The Camera Properties dialog box with the expanded view.
You can select which camera position to alter from the Camera drop-down list. In the Position drop-down list, you can select a predefined position for the camera. Many of the values in here are the same as selecting View | Type and selecting a position. If you position your camera to a different position and you want to save this position, select the Position drop-down list, and choose Save Position and enter a name for the position. Then when you want to recall this position for the currently selected camera, choose the name that you entered from the Position drop-down list.
To create a new camera, select the Create Camera tool, and drag in the Perspective window. The result is a blue camera object. Position your camera like you would any object (you can also select an object and the camera and select Arrange | Point At to direct the camera to view an object) and then select the camera in the Camera drop-down list in the Camera Properties dialog box.
Once the scene is complete, take a picture of the scene through your choice of camera. You have done this by positioning the Production Frame and then selecting Control+R to render the scene. Briefly look at some settings in the render options. Select Scene | Render Settings to display the Render Settings dialog box (see Figure 24.20).
In the Image Size tab, select the resolution and size of the finally rendered image. In the File Format dialog box, select the file type for the image. Notice that if you select the PHOTO-PAINT type, you can also check off some check boxes under the G-buffer section. These values enable you to save further information about your three-dimensional scene into separate image channels. Some image manipulation software packages can take advantage of these channels when they load your rendered image file. For example, if the Mask check box is selected, then PHOTO-PAINT Dream 3D creates a mask around all the three-dimensional objects. This saves you a lot of work in trying to create a mask around an object in an image within PHOTO-PAINT. Dream 3D does all that work for you since it knows precisely where the object edges are. For a detailed explanation of each of the G-buffer settings, select Help | Contents; then select the Find tab and use G-buffer as a search criteria. By default, the renderer selects Camera 1 to render your scene from, but in the Camera tab, you can select any other camera that you have created in your scene.
Render Settings dialog box.
Just A Minute: The G-buffer or Geometry buffer is extra information that is stored with a two-dimensional image. This information usually contains some three-dimensional information about the scene that can then be useful when used in image manipulation programs (such as PHOTO-PAINT). A good example of this is the mask information that can be saved by Dream 3D as it renders a scene to a two-dimensional image.
Lastly, after you have changed the render settings, you can save these settings as a preset by choosing Save and entering a name and optional comments. This saved set of settings can be used by selecting Scene | Render and then the name that you choose for the settings.
You have briefly skimmed some of the features in Dream 3D. The nature of this book prevents you from examining in detail all the options and effects that can be created using this amazing tool. But as you can see, you have many different things to play and experiment with. Remember to use the online help whenever you run into an option that you do not understand. Also be sure to go through the tutorials that Dream 3D comes with. Dream 3D is a good complement to CorelDRAW and PHOTO-PAINT. When you design your next project, be sure not to forget Dream 3D and what it can do to enhance that project.
The following steps create the image in Figure 24.21. In this exercise, you create a simple object, add some shading to the object, and render the scene.
Workshop image.
© Copyright, Macmillan Computer Publishing. All rights reserved.
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