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Summary.

The functions in this file create models in an IFS (Indexed Face Set) format that can be drawn using gl.drawElements with primitive type gl.TRIANGLES.

Objects have for each vertex:

• vertex coordinates,
• normal vectors,
• texture coordinates,
• vertex tangents,
• plus a list of indices for the element array buffer.

The return value of each function is an object, model, with properties:

   model.vertexPositions -- the vertex coordinates;
   model.vertexNormals -- the normal vectors;
   model.vertexTextureCoords -- the texture coordinates;
   model.vertexTangents -- the tangent vectors;
   model.indices -- the face indices.

The first four properties are of type Float32Array, while model.indices is of type Uint16Array.

• cone
• cube
• cylinder
• sphere
• torus

Summary.

Bump Mapping.

A mostly successful attempt to do bumpmapping.
Grayscale height maps are used to perturb the normals to a surface, making the surface look "bumpy".
The implementation requires tangent vectors for the surface.

The three object models used here have tangent vectors that can be passed as an attribute to the shader program.

Note: I haven't learned how to make the appropriate tangent vectors in general.
It took some experimentation for me to get them pointed in directions that seem to work.

Summary.

The TrackballRotator class implements an ArcBall like interface.

Create by Ken Shoemake in 1992, it is the de facto standard for interactive 3D model manipulation and visualization.

The class defines the following methods for an object rotator of type TrackballRotator:

• TrackballRotator#getViewMatrix()
  Returns the view transformation matrix as a regular JavaScript array of 16 elements, in column-major order, suitable for use with gl.uniformMatrix4fv or for further transformation with the glMatrix library mat4 class.
• TrackballRotator#setViewMatrix(matrix)
  Sets the view matrix.
• TrackballRotator#setView(viewDistance, viewpointDirection, viewUp)
  Sets up the view, where the parameters are optional and are used in the same way as the corresponding parameters in the constructor.
• TrackballRotator#setViewDistance(viewDistance)
  Sets the distance of the viewer from the origin without changing the direction of view.
  The parameter must be a positive number.
• TrackballRotator#getViewDistance()
  Returns the current value.
• TrackballRotator#setRotationCenter(vector)
  Sets the center of rotation.
  The parameter must be an array of (at least) three numbers. The view is rotated about this point.
  Usually, you want the rotation center to be the point that appears at the middle of the canvas, but that is not a requirement.
  The initial value is effectively equal to [0,0,0].
• TrackballRotator#getRotationCenter()
  Returns the current value.

Summary.

High performance matrix and vector operations.