On 6/10/2009 1:44 PM, kapo coulibaly wrote:
I'm trying to make sense of the following example in the package rgl:
vertices <- c(
-1.0, -1.0, 0, 1.0,
1.0, -1.0, 0, 1.0,
1.0, 1.0, 0, 1.0,
-1.0, 1.0, 0, 1.0
)
indices <- c( 1, 2, 3, 4 )
open3d()
wire3d( qmesh3d(vertices,indices) )
One would think that each vertex would have 3 coordinates (x,y,z) what
does the fourth one in the definition of the variable vertices stand
for.
By default qmesh3d uses 4-coordinate homogeneous coordinates, because
that's the coordinate system used by OpenGL. See the ?rgl::matrices
help topic for a description of how they work.
Duncan Murdoch
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