NAME
SoTextureCombine -
The SoTextureCombine class is a node for setting texture combine
functions.
This node is more or less an exact mapping of the OpenGL
ARB_texture_env_combine extension (included in OpenGL in OpenGL v1.3).
See http://oss.sgi.com/projects/ogl-
sample/registry/ARB/texture_env_combine.txt for more information about
this extension.
SYNOPSIS
#include <Inventor/nodes/SoTextureCombine.h>
Inherits SoNode.
Public Types
enum Source { PRIMARY_COLOR = SoTextureCombineElement::PRIMARY_COLOR,
TEXTURE = SoTextureCombineElement::TEXTURE, CONSTANT =
SoTextureCombineElement::CONSTANT, PREVIOUS =
SoTextureCombineElement::PREVIOUS }
enum Operand { SRC_COLOR = SoTextureCombineElement::SRC_COLOR,
ONE_MINUS_SRC_COLOR =
SoTextureCombineElement::ONE_MINUS_SRC_COLOR, SRC_ALPHA =
SoTextureCombineElement::SRC_ALPHA, ONE_MINUS_SRC_ALPHA =
SoTextureCombineElement::ONE_MINUS_SRC_ALPHA }
enum Operation { REPLACE = SoTextureCombineElement::REPLACE, MODULATE
= SoTextureCombineElement::MODULATE, ADD =
SoTextureCombineElement::ADD, ADD_SIGNED =
SoTextureCombineElement::ADD_SIGNED, SUBTRACT =
SoTextureCombineElement::SUBTRACT, INTERPOLATE =
SoTextureCombineElement::INTERPOLATE, DOT3_RGB =
SoTextureCombineElement::DOT3_RGB, DOT3_RGBA =
SoTextureCombineElement::DOT3_RGBA }
Public Member Functions
SoTextureCombine (void)
virtual void doAction (SoAction *action)
virtual void callback (SoCallbackAction *action)
virtual void GLRender (SoGLRenderAction *action)
virtual void pick (SoPickAction *action)
Static Public Member Functions
static void initClass (void)
Public Attributes
SoMFEnum rgbSource
SoMFEnum alphaSource
SoMFEnum rgbOperand
SoMFEnum alphaOperand
SoSFEnum rgbOperation
SoSFEnum alphaOperation
SoSFFloat rgbScale
SoSFFloat alphaScale
SoSFVec4f constantColor
Protected Member Functions
virtual ~SoTextureCombine ()
Detailed Description
The SoTextureCombine class is a node for setting texture combine
functions.
This node is more or less an exact mapping of the OpenGL
ARB_texture_env_combine extension (included in OpenGL in OpenGL v1.3).
See http://oss.sgi.com/projects/ogl-
sample/registry/ARB/texture_env_combine.txt for more information about
this extension.
Basically this node lets you specify up to three sources, and a
function to combine those sources. In addition to the function, it’s
possible to apply simple operands on the sources. In the documentation
below, the sources will be called Arg0, Arg1, and Arg2, just like in
the ARB_texture_env_mode specification.
It’s possible to specify both a color and an alpha operation.
This node has many fields, but usually it is sufficient to set only one
or very few fields. The selected operation decides which values you
need to set. One common example is to add a light map to textured
geometry. A lightmap can look like this:
The example below just shows how to apply the lightmap to a cube, with
one light source on each side of the cube. Usually the texture
coordinates are calculated so that a spot light or a point light is
simulated.
Texture2 { filename "wood.jpg" }
Switch {
whichChild -3 # use to toggle lightmap on/off
TextureUnit {
unit 1
}
TextureCombine {
rgbOperation ADD_SIGNED
rgbSource [PREVIOUS, TEXTURE]
rgbOperand [SRC_COLOR, SRC_COLOR ]
alphaOperation REPLACE
alphaSource [TEXTURE]
alphaOperand [SRC_ALPHA]
}
Texture2 { filename "lightmap.jpg" }
TextureUnit { unit 0 }
}
Cube { }
.fi
The scene above in a viewer:
In addition to the functions you can set in rgbOperation (or alphaOperation), it’s possible to create more complex texture functions by combining two textures that have already been combined. You can use the SoSceneTexture2 node to create those textures. Below is an example that shows how to implement Arg0*Arg1 + Arg2*Arg0, where Arg0 = texture1 RGB, Arg1 = texture2 RGB, Arg2 = texture 2 alpha:
ShapeHints { vertexOrdering COUNTERCLOCKWISE shapeType SOLID }
Separator {
SceneTexture2 {
size 256 256
transparencyFunction NONE
scene Separator {
OrthographicCamera {
height 2
aspectRatio 1
position 0 0 1
viewportMapping LEAVE_ALONE
}
LightModel { model BASE_COLOR }
Coordinate3 {
point [ -1 -1 0, 1 -1 0, 1 1 0, -1 1 0 ]
}
DEF texture1 Texture2 { filename "texture1.png" }
TextureUnit { unit 1 }
TextureCombine {
rgbOperation MODULATE
rgbSource [ PREVIOUS, TEXTURE ]
rgbOperand [ SRC_COLOR, SRC_COLOR ]
alphaOperation REPLACE
alphaSource [TEXTURE]
alphaOperand [ SRC_ALPHA ]
}
DEF texture2 Texture2 { filename "texture2_with_alpha.png" }
TextureCoordinate2 {
point [0 0, 1 0, 1 1, 0 1]
}
FaceSet { numVertices 4 }
}
}
TextureUnit { unit 1 }
TextureCombine {
rgbOperation ADD
rgbSource [ PREVIOUS, TEXTURE ]
rgbOperand [ SRC_COLOR, SRC_COLOR ]
alphaOperation REPLACE
alphaSource [TEXTURE]
alphaOperand [ SRC_ALPHA ]
}
SceneTexture2 {
size 256 256
transparencyFunction NONE
scene Separator {
OrthographicCamera {
height 2
aspectRatio 1
position 0 0 1
viewportMapping LEAVE_ALONE
}
LightModel { model BASE_COLOR }
Coordinate3 {
point [ -1 -1 0, 1 -1 0, 1 1 0, -1 1 0 ]
}
USE texture1
TextureUnit { unit 1 }
TextureCombine {
rgbOperation MODULATE
rgbSource [ PREVIOUS, TEXTURE ]
rgbOperand [ SRC_COLOR, SRC_ALPHA ]
alphaOperation REPLACE
alphaSource [TEXTURE]
alphaOperand [ SRC_ALPHA ]
}
USE texture2
TextureCoordinate2 {
point [0 0, 1 0, 1 1, 0 1]
}
FaceSet { numVertices 4 }
}
}
# map resulting texture onto a Cube
Cube { }
}
.fi
It should be possible to create almost any kind of texture function using this scheme, at the cost of extra texture memory usage (the intermediate textures), of course.
FILE FORMAT/DEFAULTS:
TextureCombine {
rgbSource [ ]
alphaSource [ ]
rgbOperand [ ]
alphaOperand [ ]
rgbOperation MODULATE
alphaOperation MODULATE
rgbScale 1
alphaScale 1
constantColor 1 1 1 1
}
Since:
Coin 2.3
Member Enumeration Documentation
enum SoTextureCombine::Source For enumerating combiner sources.
Enumerator:
PRIMARY_COLOR
Choose primary color as source.
TEXTURE
Choose texture as source.
CONSTANT
Choose the constantColor field as source.
PREVIOUS
Choose the previous unit’s texture as source.
enum SoTextureCombine::Operand For enumerating source operands.
Enumerator:
SRC_COLOR
Use the source color as operand.
ONE_MINUS_SRC_COLOR
Use one minus source color as operand.
SRC_ALPHA
Use the source alpha as operand.
ONE_MINUS_SRC_ALPHA
Use one minus source alpha as operand.
enum SoTextureCombine::Operation For enumerating combiner
operations/functions.
Enumerator:
REPLACE
dst = Arg0
MODULATE
dst = Arg0 * Arg1
ADD dst = Arg0 + Arg1
ADD_SIGNED
dst = Arg0 + Arg1 - 0.5
SUBTRACT
dst = Arg0 - Arg1
INTERPOLATE
dst = Arg0 * (Arg2) + Arg1 * (1-Arg2)
DOT3_RGB
Dot product of Arg0 and Arg1
DOT3_RGBA
Dot product (including alpha) of Arg0 and Arg1
Constructor & Destructor Documentation
SoTextureCombine::SoTextureCombine (void) Constructor.
SoTextureCombine::~SoTextureCombine () [protected, virtual] Destructor.
Member Function Documentation
void SoTextureCombine::initClass (void) [static] Sets up initialization for
data common to all instances of this class, like submitting necessary
information to the Coin type system.
Reimplemented from SoNode.
void SoTextureCombine::doAction (SoAction * action) [virtual] This function
performs the typical operation of a node for any action.
Reimplemented from SoNode.
void SoTextureCombine::callback (SoCallbackAction * action) [virtual]
Action method for SoCallbackAction.
Simply updates the state according to how the node behaves for the
render action, so the application programmer can use the
SoCallbackAction for extracting information about the scene graph.
Reimplemented from SoNode.
void SoTextureCombine::GLRender (SoGLRenderAction * action) [virtual]
Action method for the SoGLRenderAction.
This is called during rendering traversals. Nodes influencing the
rendering state in any way or who wants to throw geometry primitives at
OpenGL overrides this method.
Reimplemented from SoNode.
void SoTextureCombine::pick (SoPickAction * action) [virtual] Action method
for SoPickAction.
Does common processing for SoPickAction action instances.
Reimplemented from SoNode.
Author
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