This section explains how to create and place 3D models, focusing on the various built-in standard models provided by VCSSL.

What Is a Model?

A model represents a three-dimensional shape, constructed from a collection of small polygons. You can think of it like a paper craft made of many flat pieces assembled into a 3D form.

For example, as shown above, a sphere model in VCSSL is made up of a large number of rectangles, arranged in a pattern similar to the lines of latitude and longitude on a globe. (*)

While you can generate your own custom polygon groups to build models in VCSSL, a variety of basic shape models are already available as standard.

In this section and those that follow, we’ll focus on working with these standard models.

Creating Models

Creating Standard Models

To create a standard model, use one of the "new...Model" functions, where "..." is the name of the specific model type.

This function generates the specified model and returns a model ID that you can use to manipulate or place the model.

Creating Custom Models

To create a model from your own collection of polygons, use the newModel(...) function. Polygon creation and manipulation will be covered in the next section.

This function combines the specified polygons into a single model and returns its model ID. The advantage of grouping polygons into a model is that you can perform transformations like translation and rotation on the entire model at once.

Creating a Copy of a Model

Placing Models

You can also specify a coordinate system for placement (coordinate systems will be covered later in this guide):

Standard 3D Models

Now let's look at the various built-in standard models supported by VCSSL and how to create them.

Axis Model

The axis model is used to indicate directions in 3D space. You could say that setting up a 3DCG scene begins by placing this model -- it's a very important element for spatial reference.

Sphere Model

The more polygons used, the smoother the surface becomes; fewer polygons will make it appear more faceted. This model is placed such that its center (centroid) aligns with the origin of the coordinate system.

Box Model

This model is placed so that its center (centroid) aligns with the origin. Note that some libraries or languages may define the model such that a corner or face aligns with the origin, so be aware of this difference.

Cylinder Model

This model is placed such that the center of its bottom face aligns with the origin.

Tube Model: Open-Ended Cylindrical (Tube) Model

To create an open-ended cylindrical (tube) model, use the newTubeModel(...) function:

This model is also placed so that the center of its bottom face aligns with the origin.

Cone Model

Shade Model: Open-Ended Cone Model

To create an open-ended cone (shade-like) model, use the newShadeModel(...) function:

This model is also placed so that the center of its base aligns with the origin.

Disk Model

Face Orientation and Backface Culling

By default, only the front faces are rendered -- back faces are omitted unless explicitly enabled. This technique is known as backface culling, and it's used to skip rendering surfaces that are not visible from the current viewpoint, reducing rendering cost and improving performance.

For example, the disk model described above has its front face pointing in the positive Z direction upon creation.

If you view it from the negative Z direction, the back face will be invisible due to culling. To make both sides visible, you can disable backface culling like this:

Example Program

Now, let's try using the standard models introduced above. Write and run the following code:


import graphics3d.Graphics3DFramework;
import Graphics3D;

// The entry point of the program
void onStart ( int rendererID ) {

	// Optional: Set the window size and background color
	setWindowSize( 800, 600 );
	setBackgroundColor( 0, 0, 0, 255 );

	
	// Create and mount an axis model
	int axis = newAxisModel( 3.0, 3.0, 3.0 );
	mountModel( axis, rendererID );

	// Create and mount a sphere model
	int sphere = newSphereModel( 0.5, 0.5, 0.5, 10, 7 );
	mountModel( sphere, rendererID );

	// Create and mount a box model
	int box = newBoxModel( 1.0, 1.0, 1.0 );
	mountModel( box, rendererID );
	moveModel( box, 1.25, 0.0, 0.0 ); // Translate

	// Create and mount a cylinder model
	int cylinder = newCylinderModel( 0.5, 0.5, 1.0, 20, 1 );
	mountModel( cylinder, rendererID );
	moveModel( cylinder, 2.5, 0.0, 0.0 ); // Translate

	// Create and mount a tube (open-ended cylinder) model
	int tube = newTubeModel( 0.5, 0.5, 1.0, 20, 1 );
	mountModel( tube, rendererID );
	moveModel( tube, 0.0, 1.25, 0.0 ); // Translate
	// setModelCull( tube, false, false ); // Uncomment to show the inside surface

	// Create and mount a cone model
	int cone = newConeModel( 0.5, 0.5, 1.0, 20, 1 );
	mountModel( cone, rendererID );
	moveModel( cone, 1.25, 1.25, 0.0 ); // Translate

	// Create and mount a shade (open-ended cone) model
	int shade = newShadeModel( 0.5, 0.5, 1.0, 20, 1 );
	mountModel( shade, rendererID );
	moveModel( shade, 2.5, 1.25, 0.0 ); // Translate
	// setModelCull( shade, false, false ); // Uncomment to show the inside surface

	// Create and mount a disk model
	int disk = newDiskModel( 0.5, 0.5, 20 );
	mountModel( disk, rendererID );
	moveModel( disk, 0.0, 2.5, 0.0 ); // Translate
	// setModelCull( disk, false, false ); // Uncomment to show the back side
}

Sample.vcssl

When you run this program, various standard models will appear on a black background.

Note that the inside surface of the tube model is considered a back face, so it is not rendered by default. To render the inside, remove the comment from the line "setModelCull(tube, false, false);" after creating the model. The same applies to the shade (open-ended cone) model and the disk model.

Creating and Placing 3D Models (Standard Model Types Included)