# Lighting

For 3D scenes, GLMakie offers several attributes to control the lighting of the scene. These are set per plot.

• ambient::Vec3f0: Objects should never be completely dark; we use an ambient light to simulate background lighting, and give the object some color. Each element of the vector represents the intensity of color in R, G or B respectively.

• diffuse::Vec3f0: Simulates the directional impact which the light source has on the plot object. This is the most visually significant component of the lighting model; the more a part of an object faces the light source, the brighter it becomes. Each element of the vector represents the intensity of color in R, G or B respectively.

• specular::Vec3f0: Simulates the bright spot of a light that appears on shiny objects. Specular highlights are more inclined to the color of the light than the color of the object. Each element of the vector represents the intensity of color in R, G or B respectively.

• shininess::Float32: Controls the shininess of the object. Higher shininess reduces the size of the highlight, and makes it sharper. This value must be positive.

• lightposition::Vec3f0: The location of the main light source; by default, the light source is at the location of the camera.

## SSAO

GLMakie also implements screen-space ambient occlusion, which is an algorithm to more accurately simulate the scattering of light. There are a couple of controllable scene attributes nested within the SSAO toplevel attribute:

• radius sets the range of SSAO. You may want to scale this up or down depending on the limits of your coordinate system
• bias sets the minimum difference in depth required for a pixel to be occluded. Increasing this will typically make the occlusion effect stronger.
• blur sets the (pixel) range of the blur applied to the occlusion texture. The texture contains a (random) pattern, which is washed out by blurring. Small blur will be faster, sharper and more patterned. Large blur will be slower and smoother. Typically blur = 2 is a good compromise.
Note

The SSAO postprocessor is turned off by default to save on resources. To turn it on, set GLMakie.enable_SSAO[] = true, close any existing GLMakie window and reopen it.

## Matcap

A matcap (material capture) is a texture which is applied based on the normals of a given mesh. They typically include complex materials and lighting and offer a cheap way to apply those to any mesh. You may pass a matcap via the matcap attribute of a mesh, meshscatter or surface plot. Setting shading = false is suggested. You can find a lot matcaps here.

## Examples

using GLMakie

xs = -10:0.1:10
ys = -10:0.1:10
zs = [10 * (cos(x) * cos(y)) * (.1 + exp(-(x^2 + y^2 + 1)/10)) for x in xs, y in ys]

# Or use an LScene within a Figure
scene = Scene()
surface!(
scene, xs, ys, zs, colormap = (:white, :white),

# Light comes from (0, 0, 15), i.e the sphere
lightposition = Vec3f0(0, 0, 15),
# base light of the plot only illuminates red colors
ambient = Vec3f0(0.3, 0, 0),
# light from source (sphere) illuminates yellow colors
diffuse = Vec3f0(0.4, 0.4, 0),
# reflections illuminate blue colors
specular = Vec3f0(0, 0, 1.0),
# Reflections are sharp
shininess = 128f0
)
mesh!(scene, Sphere(Point3f0(0, 0, 15), 1f0), color=RGBf0(1, 0.7, 0.3))
scene
using GLMakie
GLMakie.enable_SSAO[] = true
close(GLMakie.global_gl_screen()) # close any open screen

# Alternatively:
# fig = Figure()
# scene = LScene(fig[1, 1], scenekw = (SSAO = (radius = 5.0, blur = 3), show_axis=false, camera=cam3d!))
# scene.scene[:SSAO][:bias][] = 0.025

scene = Scene(show_axis = false)

# SSAO attributes are per scene
scene
using FileIO
mesh(catmesh, matcap=gold, shading=false)