Generic 3D interface

Description

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 quadrangle meshes (qmesh3d).
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 difference between the r3d functions and the rgl.* functions is that 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 increasingfrom 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 other difference is that the r3d functions change the mouse mode to use a 'trackball' on the left mouse button.

The example code below illustrates the two coordinate systems.

See Also

points3d lines3d segments3d triangles3d quads3d text3d spheres3d sprites3d terrain3d select3d dot3d wire3d shade3d transform3d rotate3d subdivision3d qmesh3d cube3d rgl

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)

     rgl.open()
     rgl.texts(x,y,z,labels)
     rgl.texts(1,1,1,"rgl.* coordinates")
     rgl.lines(x[i],y[i],z[i])

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