SCENE.md

lumen

scene description

• usage
• commands
  • Display
  • Resolution
  • PixelSamples
  • DepthOfField
  • WorldBegin
  • WorldEnd
  • Geometry
    • mesh
  • ObjectBegin
  • ObjectEnd
  • Light
    • point
    • directional
    • environment
  • Material
    • matte
    • chrome
    • plastic
    • glass
  • Projection
  • Translate
  • Rotate
  • Scale

usage

Lumen scenes are described in separate files using the commands listed in this file. Most scenes will follow the same format:

1. Set image characteristics.

Display "image.bmp"     # File gets saved to ./image.bmp
Resolution 640 480      # Image is 640x480 pixels
PixelSamples 2 2        # 4 samples per pixel (2 horizontal, 2 vertical)

2. Set up the camera. All transformations outside of WorldBegin/WorldEnd affect the camera. Transformations are applied in the order they are specified.

# Rotate the camera 27 degrees on the x-axis and then translate. Add a 45 degree
# FOV perspective projection.
Rotate 27 1 0 0
Translate 0 0.5 -0.7
Projection 45

3. Describe the world. Geometry and light sources are placed between the WorldBegin/WorldEnd commands. Geometry is placed in ObjectBegin/ObjectEnd blocks. All the state specified between these commands only apply to the geometry in the block. The previous state is restored after ObjectEnd.

WorldBegin
    # List all of the light sources.
    Light "directional"

    # For each object in the scene, create a ObjectBegin/ObjectEnd block and
    # set transformations and material properties for the geometry.
    ObjectBegin
        Scale 0.2 0.2 0.2
        Rotate -10 0 1 0

        Material "matte" "diffusecolor" [0.3 0.6 0.6]
        Geometry "mesh" "meshname" "../../../dragon.xmesh"
    ObjectEnd

    ObjectBegin
        Scale 10 10 10

        Material "matte"
        Geometry "rectangle"
    ObjectEnd
WorldEnd

commands

Display

Set the image file name. The file is saved relative to the location where the lumen command was executed.

Display "FILENAME"

Resolution

Set the image size.

Resolution WIDTH HEIGHT

PixelSamples

Set the number of horizontal and vertical pixel samples. Larger numbers result in slower computation times, but higher image quality.

PixelSamples NUM_SAMPLES_X NUM_SAMPLES_Y

DepthOfField

Set depth of field parameters.

DepthOfField FSTOP FOCAL_LENGTH FOCAL_DISTANCE

WorldBegin

Begin describing the scene layout. This must be used after the camera transformations are complete and before Geometry is defined.

WorldBegin

WorldEnd

End the scene description. This command launches the rendering process and must be the last command in the file.

WorldEnd

Geometry

Create geometry.

Geometry TYPE PARAMETER_LIST

Geometry type can be: "rectangle", "sphere", or "mesh".

mesh

Parameter	Description	Value	Default
meshname	Filepath to the mesh data	string	None

ObjectBegin

Start describing a new object in the world. This function creates a new object scope that allows geometry hierarchies to be created. The transformations within the scope only apply to the geometry defined in the same scope.

ObjectBegin

ObjectEnd

Finish describing an object in the world. This function restores the previous transformation state that was set before ObjectBegin was used.

ObjectEnd

Light

Create a light source.

Light TYPE PARAMETER_LIST

Light type can be: "point", "directional", or "environment".

point

Parameter	Description	Value	Default
position	Position of the light in world space	[X Y Z]	[0 0 0]
color	light color	[R G B]	[1 1 1]

directional

Parameter	Description	Value	Default
direction	Direction of light emission	[X Y Z]	[0 -1 0]
color	light color	[R G B]	[1 1 1]

environment

Parameter	Description	Value	Default
texturename	Filepath to a cubemap	string	None
color	light color	[R G B]	[1 1 1]

Material

Set the material to use for subsequent geometry.

Material TYPE PARAMETER_LIST

Material type can be: "matte", "chrome", "plastic", or "glass".

matte

Parameter	Description	Value	Default
diffusecolor	Color of diffuse reflection	[R G B]	[1 1 1]
texturename	Filepath to a diffuse texture map	string	None

chrome

Parameter	Description	Value	Default
specularcolor	Color of specular reflection	[R G B]	[1 1 1]

plastic

Parameter	Description	Value	Default
diffusecolor	Color of diffuse reflection	[R G B]	[0.5 0.5 0.5]
specularcolor	Color of specular reflection	[R G B]	[0.5 0.5 0.5]
texturename	Filepath to a diffuse texture map	string	None
exponent	Specular reflection exponent	float	32.0

glass

Parameter	Description	Value	Default
specularcolor	Color of specular reflection/refraction	[R G B]	[1 1 1]
ni	Refractive index of the material surrounding an object	float	1.0
nt	Refractive index of the material	float	1.5

Projection

Apply a perspective projection to the current transformation.

Projection FOV

Translate

Translate relative to the current position.

Translate X Y Z

Rotate

Rotate along an axis through the origin.

Rotate DEGREES X Y Z

Scale

Scale along each axis.

Scale X Y Z