R: Light an image using the alpha channel as a bump map.

feDiffuseLighting {gridSVG} | R Documentation

## Light an image using the alpha channel as a bump map.

### Description

This filter primitive lights an image using the alpha channel as a bump map. The resulting image is an RGBA opaque image based on the light colour with `alpha = 1` everywhere. The lighting calculation follows the standard diffuse component of the Phong lighting model. The resulting image depends on the light colour, light position and surface geometry of the input bump map.

### Usage

    feDiffuseLighting(input = NA,
                      surfaceScale = 1, diffuseConstant = 1,
                      kernelUnitLength = NA, col = "white",
                      lightSource = NULL, ...)

### Arguments

`input` | Identifies an input for this filter primtive. See `filterInputs`.
`surfaceScale` | Scale applied to the input alpha surface.
`diffuseConstant` | `kd` in the Phong lighting model. Must be non-negative.
`kernelUnitLength` | The first number is the `dx` value. The second number is the `dy` value. If the `dy` value is not specified, it defaults to the same value as `dx`. Indicates the intended distance in current filter units (i.e., units as determined by the value of parent filter container's `primitiveUnits`) for `dx` and `dy`, respectively, in the surface normal calculation formulas. By specifying value(s) for `kernelUnitLength`, the kernel becomes defined in a scalable, abstract coordinate system. If `kernelUnitLength` is not specified, the `dx` and `dy` values should represent very small deltas relative to a given (x,y) position, which might be implemented in some cases as one pixel in the intermediate image offscreen bitmap, which is a pixel-based coordinate system, and thus potentially not scalable.
`col` | The colour to apply to the light from `lightSource`.
`lightSource` | A light source object, produced by one of `feDistantLight`, `fePointLight`, or `feSpotLight`.
`...` | Further arguments to be passed onto `fe`.

### Details

For more information about this primitive, consult the reference to the SVG specification.

### Value

An `fe.diffuse.lighting` object.

### Author(s)

Simon Potter

### References

http://www.w3.org/TR/SVG/filters.html#feDiffuseLightingElement

### See Also

`filterEffect` `fe`, `feDistantLight`, `fePointLight`, `feSpotLight`.

[Package gridSVG version 1.6-0 Index]