EntityLightChannel

EntityLightChannel 〔BlitzLLVM〕

Command Index · Blitz3D · Entities

EntityLightChannel:Void entity:Int32, channel:Int32

Parameter	Mode	Type	Default	Description
entity	In	Int32	required	Entity handle, of an entity or of a light.
channel	In	Int32	required	The channels as bits (a UInt64): bit 0 is channel 1 up to bit 63 for channel 64.

Description

〔BlitzLLVM〕 This command does not exist in the original Blitz products. BlitzLLVM adds it.

Sets the light channels of an entity. A channel is one bit of channel, so there are 64 of them (1, 2, 4, 8 and so on up to 9223372036854775808) and the values add up: 3 is channel 1 and 2. The default is all 64 channels, so entities that never use channels behave as before. Channel 32 and up need a ULong, because an Int only has 32 bits.

Lights are entities too, so this sets the channels a light shines into. An entity is only lit by the lights that share at least one channel with it, and 0 means no light reaches it (and a light with 0 lights nothing). Meshes, sprites and terrains all use it, and the channel of an entity is not passed on to its children.

AmbientLight is not a light of any channel: it lights every entity, and an entity with EntityFX 1 ignores lights anyway.

Which lights count is decided per entity: only the lights that share a channel with it are considered, and the 8 of them that matter the most to it light it (see Many-Lights). Lights of other channels never use up one of the 8.

Examples

Graphics3D 320, 240, 0, 2
SetBuffer BackBuffer()
camera = CreateCamera()
PositionEntity camera, 0, 0, -9
AmbientLight 10, 10, 10
; A red light for channel 1 and a blue light for channel 2.
red = CreateLight(2)
PositionEntity red, 0, 3, -3
LightColor red, 255, 0, 0
EntityLightChannel red, 1
blue = CreateLight(2)
PositionEntity blue, 0, 3, -3
LightColor blue, 0, 0, 255
EntityLightChannel blue, 2
; The left ball is in channel 1, the middle one in channel 2 and the right one in both.
For i = 0 To 2
	ball = CreateSphere(24)
	PositionEntity ball, i * 3 - 3, 0, 0
	EntityLightChannel ball, i + 1
Next
RenderWorld
Flip
WaitKey

Without channels all three balls are lit by both lights and look the same (left), with them each ball only gets the light of its channels (right):

This is a BlitzLLVM extension: the originals have no light channels.

Media

Related Commands

EntityAlpha, EntityAutoFade, EntityBlend, EntityClass, EntityColor, EntityDepthFade 〔BlitzLLVM〕, EntityDistance, EntityFX

Command Index · Blitz3D · Entities