SoTextureCombine(3) The SoTextureCombine class is a node for setting texture combine functions.

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


virtual SoType getTypeId (void) const

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 SoType getClassTypeId (void)

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 const SoFieldData * getFieldData (void) const

virtual ~SoTextureCombine ()

Static Protected Member Functions


static const SoFieldData ** getFieldDataPtr (void)

Additional Inherited Members

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

SoType SoTextureCombine::getClassTypeId (void) [static]

SoTextureCombine::rgbSource

The color sources. This field is empty by default, but you can insert up to three values [Arg0, Arg1, Arg2]. When the field contains less than three values, the default [TEXTURE, PREVIOUS, CONSTANT], will be used for missing values.

For texture unit 0, PREVIOUS maps to PRIMARY_COLOR,

SoTextureCombine::alphaSource

The alpha sources. This field is empty by default, but you can insert up to three values [Arg0, Arg1, Arg2]. When the field contains less than three values, the default [TEXTURE, PREVIOUS, CONSTANT], will be used for missing values.

For texture unit 0, PREVIOUS maps to PRIMARY_COLOR,

SoTextureCombine::rgbOperand

The color operands. This field is empty by default, but you can insert up to three values. When the field contains less than three values, the default [SRC_COLOR, SRC_COLOR, SRC_COLOR] will be used for missing values.

SoTextureCombine::alphaOperand

The alpha operands. This field is empty by default, but you can insert up to three values. When the field contains less than three values, the default [SRC_ALPHA, SRC_ALPHA, SRC_ALPHA] will be used for missing values. Please not that only SRC_ALPHA and ONE_MINUS_SRC_ALPHA are valid operands for alpha operations.

SoTextureCombine::rgbOperation

The color operation. Default value is MODULATE.

SoTextureCombine::alphaOperation

The alpha operation. Default value is MODULATE.

SoTextureCombine::rgbScale

Scale color result by this value. Supported values are 1, 2, and 4.

SoTextureCombine::alphaScale

Scale alpha result by this value. Supported values are 1, 2, and 4.

SoTextureCombine::constantColor

The constant color (when CONSTANT is used as source). Default value is (1,1,1,1).

Reimplemented from SoNode.

SoType SoTextureCombine::getTypeId (void) const [virtual]

Returns the type identification of an object derived from a class inheriting SoBase. This is used for run-time type checking and 'downward' casting.

Usage example: 

  void foo(SoNode * node)
  {
    if (node->getTypeId() == SoFile::getClassTypeId()) {
      SoFile * filenode = (SoFile *)node;  // safe downward cast, knows the type
    }
  }

For application programmers wanting to extend the library with new nodes, engines, nodekits, draggers or others: this method needs to be overridden in all subclasses. This is typically done as part of setting up the full type system for extension classes, which is usually accomplished by using the pre-defined macros available through for instance Inventor/nodes/SoSubNode.h (SO_NODE_INIT_CLASS and SO_NODE_CONSTRUCTOR for node classes), Inventor/engines/SoSubEngine.h (for engine classes) and so on.

For more information on writing Coin extensions, see the class documentation of the toplevel superclasses for the various class groups.

Implements SoBase.

const SoFieldData ** SoTextureCombine::getFieldDataPtr (void) [static], [protected]

This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

Reimplemented from SoNode.

const SoFieldData * SoTextureCombine::getFieldData (void) const [protected], [virtual]

Returns a pointer to the class-wide field data storage object for this instance. If no fields are present, returns NULL.

Reimplemented from SoFieldContainer.

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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