surface: add height-field surface shape
In trestletech/rgl: 3D visualization device system (OpenGL)

Description Usage Arguments Details Value See Also Examples

Adds a surface to the current scene. The surface is defined by a matrix defining the height of each grid point and two vectors defining the grid.

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rgl.surface(x, z, y, coords = 1:3, ..., 
            normal_x = NULL, normal_y = NULL, normal_z = NULL,
            texture_s = NULL, texture_t = NULL)

`x`	values corresponding to rows of `y`, or matrix of x coordinates
`y`	matrix of height values
`z`	values corresponding to columns of `y`, or matrix of z coordinates
`coords`	See details
`...`	Material and texture properties. See `rgl.material` for details.
`normal_x, normal_y, normal_z`	matrices of the same dimension as `y` giving the coordinates of normals at each grid point
`texture_s, texture_t`	matrices of the same dimension as `z` giving the coordinates within the current texture of each grid point

Adds a surface mesh to the current scene. The surface is defined by the matrix of height values in y, with rows corresponding to the values in x and columns corresponding to the values in z.

The coords parameter can be used to change the geometric interpretation of x, y, and z. The first entry of coords indicates which coordinate (1 = X, 2 = Y, 3 = Z) corresponds to the x parameter. Similarly the second entry corresponds to the y parameter, and the third entry to the z parameter. In this way surfaces may be defined over any coordinate plane.

If the normals are not supplied, they will be calculated automatically based on neighbouring points.

Texture coordinates run from 0 to 1 over each dimension of the texture bitmap. If texture coordinates are not supplied, they will be calculated to render the texture exactly once over the grid. Values greater than 1 can be used to repeat the texture over the surface.

rgl.surface always draws the surface with the ‘front’ upwards (i.e. towards higher y values). This can be used to render the top and bottom differently; see rgl.material and the example below.

If the x or z argument is a matrix, then it must be of the same dimension as y, and the values in the matrix will be used for the corresponding coordinates. This is used to plot shapes such as cylinders where y is not a function of x and z.

NA values in the height matrix are not drawn.

The object ID of the displayed surface is returned invisibly.

rgl.material, surface3d, terrain3d. See persp3d for a higher level interface.

#
# volcano example taken from "persp"
#

data(volcano)

y <- 2 * volcano        # Exaggerate the relief

x <- 10 * (1:nrow(y))   # 10 meter spacing (S to N)
z <- 10 * (1:ncol(y))   # 10 meter spacing (E to W)

ylim <- range(y)
ylen <- ylim[2] - ylim[1] + 1

colorlut <- terrain.colors(ylen) # height color lookup table

col <- colorlut[ y - ylim[1] + 1 ] # assign colors to heights for each point

rgl.open()
rgl.surface(x, z, y, color = col, back = "lines")