|Applicable Blender version: 2.49.|
Why a goblet? After all, goblets (fancy containers for consumable liquids) are not really all that important in the real world. However, they represent a very large class of interesting objects: those that are radially symmetric. Also, they are fun to play with.
To model a goblet and actually see the result, we do the following steps:
- create the actual mesh of the object.
- apply a material to the object.
- create and light a scene to display the goblet
- render the scene.
The following tutorials demonstrate three different approaches to creating the mesh model, and then show two different materials (glass and silver) that may be applied to the goblet. Finally, we add the minimal elements to the scene to permit an "interesting" rendering.
Three ways to build the meshEdit
As a beginner, you may wonder why we describe three different ways to build the mesh. After all, surely the Pros know of a "best" method?! The answer is that there is not really a best method. Blender provides a sophisticated toolkit, and different blender artists will become familiar with different tools. If, after you gain experience, you become comfortable with cube extrusion, then this may become your preferred tool. If you need more than four vertices per "circle" you may find that cylinder extrusion is better for some particular object. If you are comfortable with "spinning" an object, then spinning may be right for you. All three techniques generate an object that is defined by a set of vertices on a set of circles that are "stacked" on a common axis.
After we build the mesh using one of the three methods, we can apply any number of fancy techniques for texture and rendering. We provide two simple "cookbook" approaches in this section so you can see the result, but materials are treated much more extensively in other sections of the book.
In the next three sections of the book we describe the "cube extrusion" approach, the "cylinder" approach, and the "spin" approach. Following sections describe three textures that can be applied to objects that are created with any of the approaches, and the final tutorial provides a simple way to render the result.
The "cube extrusion" approach is a basic technique that all blender artists will become familiar with, to model most types of objects. Since it is such a basic technique, it may become the most efficient way for you to create objects, and you may choose to use it wherever possible rather than switching to a less familiar technique. You can see from the tutorial that this technique is perfectly acceptable for goblets, and by extension it will work for similar objects.
You may prefer the "cylinder extrusion" technique when you need more than four vertices per circle, because cylinder extrusion is very similar to cube extrusion. Thus your proficiency with cube extrusion will directly carry over to cylinder extrusion.
"Spinning" is conceptually different, even though it creates the same mesh as cylinder extrusion. Spinning is the easiest way to create a radially symmetric model from a two-dimensional description of the cross-section of an object.
How many circles?Edit
Each of the three methods defines a set of stacked circles, with vertices equidistant around each circle. The "cube extrusion" technique has four vertices on each circle, while the cylinder and spin techniques have a user-specified number of vertices per circle. But how did we pick the number of circles and the spacing between them?
The answer is that we know in advance that we intend to use a technique called "subsurf". Subsurf interpolates additional vertices between those we explicitly specify, and this "smooths out" the profile of our goblet.
This will cause problems where we need a fairly sharp "bend" in the profile, as between the base and the stem and between the stem and the "bulb" of the goblet. At each point in the profile that has a (fairly) sharp bend, we need for the vertical circles to be close to each other. The two images illustrate this effect. Each image shows an outline of the object, the spun object, and the result after subsurf (level 2) has been applied. The outlines and the spun images are nearly identical, but the subsurfed result is very different, because there are three extra vertices in the second outline: one just above the edge of the base, one at the top of the base, and one below the bulb: these are the three locations where we need relatively sharp changes in contour. When we spin the outline, the first outline generates seven circles and two degenerate circles, while the second outline generates ten circles and two degenerate circles. Those extra three circles make all the difference. The same phenomenon occurs with the other two modelling techniques.