setPBRshaders {rgl2gltf}

Set shaders for physically based rendering.

Description

The glTF format is designed to hold objects which are intended for "physically based rendering", where the parameters of the object map to physical properties such as metallicity, roughness, etc. This function replaces the default rgl shaders with PBR shaders based on the reference implementation in https://github.com/KhronosGroup/glTF-Sample-Viewer/tree/88eda8c5358efe03128b72b6c5f5f6e5b6d023e1/shaders.

Usage

setPBRshaders(gltf, gltfMat, id,
              scene = scene3d(minimal = TRUE),
              useIBL = TRUE,
              brdfLUT = system.file("textures/brdfLUT.png", package = "rgl2gltf"),
              IBLspecular = system.file("textures/refmap.png", package = "rgl"),
              IBLdiffuse = system.file("textures/refmapblur.jpeg", package = "rgl2gltf"),
              debugBaseColor = 0,
              debugMetallic = 0,
              debugRoughness = 0,
              debugSpecularReflection = 0,
              debugGeometricOcclusion = 0,
              debugMicrofacetDistribution = 0,
              debugSpecContrib = 0,
              debugDiffuseContrib = 0,
              debugIBLDiffuse = 1,
              debugIBLSpecular = 1,
              defines = list(),
              uniforms = list(),
              attributes = list(),
              textures = list())

Arguments

gltf, gltfMat

A "gltf" object, and a material record from it.

id, scene

The rgl id of the corresponding object and the scene holding it.

useIBL

Whether to use image based lighting.

brdfLUT

The texture to use for the "bidirectional reflectance distribution function" lookup table.

IBLspecular

The texture to use for the "image based specular lighting".

IBLdiffuse

The texture to use for the "image based diffuse lighting".

debugBaseColor, debugMetallic, debugRoughness, debugSpecularReflection, debugGeometricOcclusion, debugMicrofacetDistribution, debugSpecContrib, debugDiffuseContrib

These are flags used for debugging. Setting one of these to 1 will display just that contribution to the rendering.

debugIBLDiffuse, debugIBLSpecular

Two more debugging settings. These should be set to non-negative values to control the contribution from each of those components to the image based lighting.

defines, uniforms, attributes, textures

Values to use in setUserShaders in addition to the ones determined by this function.

Details

rgl is designed to work with WebGL version 1, which doesn't support all of the features used in the reference shaders. In particular, no extensions are assumed, and the IBL textures are single 2D textures rather than cube maps.

Value

This function modifies the id object in scene, and returns the modified scene.

Author(s)

Duncan Murdoch for the adaptation to rgl, various others for the original shaders.

References

https://github.com/KhronosGroup/glTF-Sample-Viewer

See Also

gltfWidget

Examples

# This web page has lots of sample files

samples <- "https://raw.githubusercontent.com/KhronosGroup/glTF-Sample-Models/master/2.0"

# Get one of them:  a 2 cylinder engine

gltf <- readGLB(paste0(samples, "/NormalTangentTest/glTF-Binary/NormalTangentTest.glb?raw=true"))
gltfMat <- gltf$getMaterial(0)
scene <- as.rglscene(gltf)
id <- scene$objects[[1]]$id
scene <- setPBRshaders(gltf, gltfMat, id, scene)
cat(scene$objects[[1]]$userFragmentShader)