Generic 3D interface

Generic 3D interface for 3D rendering and computational geometry.

Details

R3d is a design for an interface for 3d rendering and computation without dependency on a specific rendering implementation. R3d includes a collection of 3D objects and geometry algorithms. All r3d interface functions are named *3d. They represent generic functions that delegate to implementation functions.

The interface can be grouped into 8 categories: Scene Management, Primitive Shapes, High-level Shapes, Geometry Objects, Visualization, Interaction, Transformation, Subdivision.

The rendering interface gives an abstraction to the underlying rendering model. It can be grouped into four categories:

Scene Management:

A 3D scene consists of shapes, lights and background environment.

Primitive Shapes:

Generic primitive 3D graphics shapes such as points, lines, triangles, quadrangles and texts.

High-level Shapes:

Generic high-level 3D graphics shapes such as spheres, sprites and terrain.

Interaction:

Generic interface to select points in 3D space using the pointer device.

In this package we include an implementation of r3d using the underlying rgl.* functions.

3D computation is supported through the use of object structures that live entirely in R.

Geometry Objects:

Geometry and mesh objects allow to define high-level geometry for computational purpose such as triangle or quadrangle meshes (see mesh3d).

Transformation:

Generic interface to transform 3d objects.

Visualization:

Generic rendering of 3d objects such as dotted, wired or shaded.

Computation:

Generic subdivision of 3d objects.

At present, the main practical differences between the r3d functions and the rgl.* functions are as follows.

The r3d functions call open3d if there is no device open, and the rgl.* functions call rgl.open. By default open3d sets the initial orientation of the coordinate system in 'world coordinates', i.e. a right-handed coordinate system in which the x-axis increases from left to right, the y-axis increases with depth into the scene, and the z-axis increases from bottom to top of the screen. rgl.* functions, on the other hand, use a right-handed coordinate system similar to that used in OpenGL. The x-axis matches that of r3d, but the y-axis increases from bottom to top, and the z-axis decreases with depth into the scene. Since the user can manipulate the scene, either system can be rotated into the other one.

The r3d functions also preserve the rgl.material setting across calls (except for texture elements, in the current implementation), whereas the deprecated rgl.* functions leave it as set by the last call.

The example code below illustrates the two coordinate systems.

Examples

    
     x <- c(0, 1, 0, 0)
     y <- c(0, 0, 1, 0)
     z <- c(0, 0, 0, 1)
     labels <- c("Origin", "X", "Y", "Z")
     i <- c(1, 2, 1, 3, 1, 4)

     # *3d interface
     
     open3d()
     text3d(x, y, z, labels)
     text3d(1, 1, 1, "*3d coordinates")
     segments3d(x[i], y[i], z[i])