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Public Types | Public Member Functions | Static Public Member Functions | Public Attributes | Protected Member Functions

SoTextureCombine Class Reference

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. More...

#include <Inventor/nodes/SoTextureCombine.h>

Inheritance diagram for SoTextureCombine:
SoNode SoFieldContainer SoBase

List of all members.

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:

lightmap.jpg

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 { }

  

The scene above in a viewer:

lightmap_screenshot.png

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 { }
  }
  

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

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.

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.

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  )
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.

References SoFieldContainer::get(), SoMField::getNum(), SoAction::getState(), SoMFEnum::getValues(), PREVIOUS, SoFieldContainer::set(), SRC_ALPHA, SRC_COLOR, and TEXTURE.

Referenced by GLRender().

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.

References doAction(), DOT3_RGB, DOT3_RGBA, SoGLRenderAction::getCacheContext(), and SoDebugError::postWarning().

void SoTextureCombine::pick ( SoPickAction action) [virtual]

Action method for SoPickAction.

Does common processing for SoPickAction action instances.

Reimplemented from SoNode.


The documentation for this class was generated from the following files:

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Generated on Mon Feb 28 2011 10:12:21 for Coin by Doxygen. 1.7.3