NAME

       SoTextureScalePolicy -

       The SoTextureScalePolicy class is a node for controlling the texture scale policy.

       If a texture map is of size != 2^n, it must be scaled before OpenGL can handle it. This
       node enables you to control how/if textures are scaled before it is sent to OpenGL.

SYNOPSIS

       #include <Inventor/nodes/SoTextureScalePolicy.h>

       Inherits SoNode.

   Public Types
       enum Policy { USE_TEXTURE_QUALITY, SCALE_DOWN, SCALE_UP, FRACTURE }

   Public Member Functions
       virtual SoType getTypeId (void) const
           Returns the type identification of an object derived from a class inheriting SoBase.
           This is used for run-time type checking and 'downward' casting.
       SoTextureScalePolicy (void)
       virtual void GLRender (SoGLRenderAction *action)

   Static Public Member Functions
       static SoType getClassTypeId (void)
       static void initClass (void)

   Public Attributes
       SoSFEnum policy
       SoSFFloat quality

   Protected Member Functions
       virtual const SoFieldData * getFieldData (void) const
       virtual ~SoTextureScalePolicy ()

   Static Protected Member Functions
       static const SoFieldData ** getFieldDataPtr (void)

   Additional Inherited Members

Detailed Description

       The SoTextureScalePolicy class is a node for controlling the texture scale policy.

       If a texture map is of size != 2^n, it must be scaled before OpenGL can handle it. This
       node enables you to control how/if textures are scaled before it is sent to OpenGL.

       Also, if a texture map is bigger than the maximum OpenGL texture size (implementation and
       context dependent), it will be scaled down to the maximum size. You can avoid this by
       setting the texture policy to SoTextureScalePolicy::FRACTURE, in which case the texture
       will be split into several small subtextures before the geometry using the texture is
       rendered.

       Setting SoTextureScalePolicy::policy to SoTextureScalePolicy::FRACTURE will also cause the
       internal texture handling unit in Coin to automatically downsample the individual
       subtextures to not use more graphics card memory than necessary to cover the current
       screen size of the texture.

       These two aspects of SoTextureScalePolicy::FRACTURE rendering together, subtexture
       fracturing and automatic downsampling, makes it possible to have textures with almost
       unlimited size. The only real limit is the amount of memory on the system, since the
       entire texture must fit into CPU memory.

       The SoTextureScalePolicy::FRACTURE policy is also very handy for using the Coin library's
       built-in handling of non-power-of-2 textures. This will then be done completely
       transparent to the application programmer, for maximum convenience. Below is a very simple
       example which demonstrates how to use it. The texture has dimensions 3x3, but no scaling
       (and thereby interpolation) will have to be done when SoTextureScalePolicy::FRACTURE is
       specified:

       #Inventor V2.1 ascii

       Separator {
          TextureScalePolicy { policy FRACTURE }
          Complexity { textureQuality 0.01 }  # don't generate smoothed mipmaps
          Texture2 {
             image 3 3 4  # dimensions 3x3, RGBA (4-component) image
             0xff0000ff 0x00ff00ff 0x0000ffff  # red, green, blue
             0xffff00ff 0xff00ffff 0x00ffffff  # yellow, magenta, cyan
             0x222222ff 0x777777ff 0xccccccff  # dark, medium and light grey
          }
          Cube { }
       }

       Be aware that the triangle throughput is much slower when using the FRACTURE texture mode,
       since all triangles need to be clipped (using the CPU) against subtextures. It's therefore
       usually not a good idea to use the FRACTURE mode on large triangle meshes.

       Be aware that this class is an extension for Coin, and it is not available in the original
       SGI Open Inventor v2.1 API.

       FILE FORMAT/DEFAULTS:

       TextureScalePolicy {
           policy USE_TEXTURE_QUALITY
           quality 0.5
       }

       Since:
           Coin 2.0

Member Enumeration Documentation

   enum SoTextureScalePolicy::Policy
       Enumerates the available policy settings.

       Enumerator

       USE_TEXTURE_QUALITY
              Uses the texture quality to decide whether to scale up or down.

       SCALE_DOWN
              Always scales down.

       SCALE_UP
              Always scales up.

       FRACTURE
              Splits the texture into several subtextures, and clips the geometry into each
              subtexture. Also automatically downsamples the subtextures to not use more graphics
              card memory than necessary versus the current screen size of the texture.

       These two features makes it possible to have textures with almost unlimited size. The only
       real limit is the amount of memory on the system, since the entire texture must fit into
       CPU memory.

       Be aware that the rendering is quite slow with this mode if the texture(s) will be mapped
       onto lots of polygon primitives.

Constructor & Destructor Documentation

   SoTextureScalePolicy::SoTextureScalePolicy (void)
       Constructor.

   SoTextureScalePolicy::~SoTextureScalePolicy () [protected],  [virtual]
       Destructor.

Member Function Documentation

   SoType SoTextureScalePolicy::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 * SoTextureScalePolicy::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 SoTextureScalePolicy::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.

Member Data Documentation

   SoSFEnum SoTextureScalePolicy::policy
       The policy setting. Default value is USE_TEXTURE_QUALITY.

       USE_TEXTURE_QUALITY means that SoComplexity::textureQuality will be used to decide if the
       texture should be scaled up or down. SoComplexity::textureQuality >= 0.7 means scale up,
       while < 0.7 means scale down. Textures smaller than 256 pixels are never scaled down since
       you lose too much information.

   SoSFFloat SoTextureScalePolicy::quality
       The texture scale/resize quality. Default value is 0.5.

       This field can be used to force Coin to use a lower quality (but much faster) image resize
       function. Currently, if you set this field to a value < 0.5, a low quality resize function
       will be used, otherwise a high quality (but slow) function will be used.

Author

       Generated automatically by Doxygen for Coin from the source code.