TextureBlend texture,blend

Parameters

texture - texture handle
blend - blend mode:
0: replace - no blend
1: alpha
2: multiply (default)
3: add
4: dot3 bump
5: multiply x2

Description

Sets how a texture blends with the texture layer below it.

This is about combining texture layers within one material, not about blending with the scene (that's EntityBlend). Layer 0 combines with the entity's own colour, layer 1 combines with the result of layer 0, and so on up the stack - each layer using its own TextureBlend mode.

Multiply, the default, darkens: perfect for lightmaps and dirt over a base texture. Add brightens - glow maps. Alpha lays the texture over the layers below using its alpha channel - decals. Multiply x2 is like multiply but doubles the result, so mid-grey leaves the base unchanged and brighter values lighten it, the classic lightmap trick when lightmaps should be able to over-brighten. Dot3 treats the two layers as normal-map data for simple per-pixel bump lighting.

Set the layer a texture occupies with the index parameter of EntityTexture or BrushTexture.

See also: EntityBlend, EntityTexture, BrushTexture, TextureCoords.

Example

; TextureBlend Example
; --------------------

Graphics3D 640,480,0,2
SetBuffer BackBuffer()

camera=CreateCamera()

light=CreateLight()
RotateEntity light,45,45,0

cube=CreateCube()
PositionEntity cube,0,0,5

; Two texture layers: the logo on layer 0, chrome on layer 1.
; Layer 1 blends down onto layer 0 using its TextureBlend mode.
tex0=LoadTexture("media/b3dlogo.jpg")
tex1=LoadTexture("media/Chorme-2.BMP")
EntityTexture cube,tex0,0,0
EntityTexture cube,tex1,0,1

blend=2

While Not KeyDown(1)

    ; Keys 1-6 select blend modes 0-5 for the top layer
    If KeyHit(2) Then blend=0
    If KeyHit(3) Then blend=1
    If KeyHit(4) Then blend=2
    If KeyHit(5) Then blend=3
    If KeyHit(6) Then blend=4
    If KeyHit(7) Then blend=5
    blend_name$="do not blend"
    If blend=1 Then blend_name="no blend / alpha"
    If blend=2 Then blend_name="multiply (default)"
    If blend=3 Then blend_name="add"
    If blend=4 Then blend_name="dot3"
    If blend=5 Then blend_name="multiply 2"

    ; Set the blend mode used by texture layer 1
    TextureBlend tex1,blend

    TurnEntity cube,0,1,0

    ; Arrow keys move the camera
    If KeyDown(200) Then MoveEntity camera,0,0,0.1
    If KeyDown(208) Then MoveEntity camera,0,0,-0.1
    If KeyDown(203) Then TurnEntity camera,0,1,0
    If KeyDown(205) Then TurnEntity camera,0,-1,0

    RenderWorld

    Text 0,0,"Keys 1-6: blend mode for the chrome layer   Arrows: camera   Esc: exit"
    Text 0,20,"TextureBlend tex1,"+blend+"  ("+blend_name+")"

    Flip

Wend

End

Index