AttributeMap

Overview

AttributeMap reads data from a model for use in shading. The data can be implicit in the model (i.e. position, geometric normal) or an explicit primitive attribute added to models using the UserData object.
The following table shows what primitive attributes are expected and what values are returned with the various map_type settings:

map_type return value
primitive attribute Explicit primitive attribute specified with primitive_attribute_name and primitive_attribute_type parameters
position Position in render space P(Vec3f)
texture st Texture coordinates specified with surface_st(Vec2f) for meshes or uv(Vec2f) for points or implicit coordinates depending on geometry type
shading normal Normal specified with N(Vec3f) or implicit geometric normal
geometric normal Implicit normal calculated from geometry (faceted for meshes)
dpds Partial derivative of P with respect to s texture st coordinate
dpdt Partial derivative of P with respect to t texture st coordinate
dnds Partial derivative of shading normal with respect to s texture st coordinate
dndt Partial derivative of shading normal with respect to t texture st coordinate
map color Color from color parameter or evaluated map bound to it
hair surface P Surface position of a curve specified with surface_P(Vec3f)
hair surface N Surface normal of a curve specified with surface_N(Vec3f)
hair surface st Surface texture st of a curve specified with surface_st(Vec2f)
hair closest surface st Closest surface texture st of a curve specified with closest_surface_st(Vec2f)
id Explicit id(int) primitive attribute
velocity Explicit velocity(Vec3f) primitive attribute
acceleration Explicit acceleration(Vec3f) primitive attribute
motionvec Explicit motionvec(Vec3f) primitive attribute

Attribute Reference

Primitive Attribute attributes

primitive_attribute_name

String
default: Cd

the name of primitive attribute to display when attribute 'map type' is set to 'primitive attribute'

primitive_attribute_type

Int enum
  0 = “float”
  1 = “vec2f”
  2 = “vec3f”
  3 = “rgb” (default)
  4 = “int”

the type of primitive attribute to display when attribute 'map type' is set to 'primitive attribute'

General attributes

color

Rgb bindable
default: [ 1, 1, 1 ]

input color - preferably a connected map

default_value

Rgb bindable
default: [ 1, 1, 1 ]

default value to display when the requested attribute is not available

map_type

Int enum
  0 = “primitive attribute” (default)
  1 = “position”
  2 = “texture st”
  3 = “shading normal”
  4 = “geometric normal”
  5 = “dpds”
  6 = “dpdt”
  7 = “dnds”
  8 = “dndt”
  9 = “map color”
  12 = “hair surface P”
  13 = “hair surface N”
  14 = “hair surface st”
  15 = “hair closest surface st”
  16 = “id”
  17 = “velocity”
  18 = “acceleration”
  19 = “motionvec”
  20 = “observer direction”

No documentation available

warn_when_unavailable

Bool
default: False

Whether or not to issue a warning when the requested attribute is unavailable

Examples

-- vertex color, Cd
local attrMapPrimAttrCd = AttributeMap("attrMapPrimAttrCd") {
    --[[
        0 = prim attr
        1 = position
        2 = texture st
        3 = shading normal
        4 = geometric normal
        5 = dpds
        6 = dpdt
        7 = dnds
        8 = dndt
    ]]--
    ["map type"] = 0,
    -- 0 = float
    -- 1 = vec2
    -- 2 = vec3
    -- 3 = rgb
    ["primitive attribute type"] = 3,
    ["primitive attribute name"] = "Cd",
    ["default value"] = Rgb(0, 0, 1),
}

local attrMapPosition = AttributeMap("attrMapPosition") {
    --[[
        0 = prim attr
        1 = position
        2 = texture st
        3 = shading normal
        4 = geometric normal
        5 = dpds
        6 = dpdt
        7 = dnds
        8 = dndt
    ]]--
    ["map type"] = 1,
}