Provided by: libcoin60-doc_3.1.3-2_all bug

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
       SoTextureScalePolicy (void)
       virtual void GLRender (SoGLRenderAction *action)

   Static Public Member Functions
       static void initClass (void)

   Public Attributes
       SoSFEnum policy
       SoSFFloat quality

   Protected Member Functions
       virtual ~SoTextureScalePolicy ()

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 { }
         }
         .fi

       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

   void SoTextureScalePolicy::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 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.