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#include <OSGConfig.h> |
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using namespace OSG; |
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/*! \defgroup GrpSystemImage Image |
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\ingroup GrpSystem |
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See \ref PageSystemImage for a description. |
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*/ |
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/*! \page PageSystemImage Image |
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\latexonly Starter:NewChapter \endlatexonly |
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Defines and holds a 1D/2D/3D image and optionally a mipmap pyramid and/or a |
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list of equally sized frames with a single frameDelay. Various pixelTypes are |
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supported to handle gray and RGB color images with or without alpha channel. |
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An Image is only a container for the pixel data and image description. It does |
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not create or handle any OpenGL state elements. However, image objects are |
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utilized to handle the data for texture (e.g. osg::SimpleTextureMaterial or |
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osg::TextureChunk) or bitmap objects (e.g. osg::ImageForeground). |
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The image object holds some describing fields (e.g. width/height/depth), |
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and a single block of memory for all the raster data. |
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\image html image-mmm.png "Mem layout for Multi-Frame mip-map image data" |
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\image latex image-mmm.eps "Mem layout for Multi-Frame mip-map image data" width=14cm |
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The image data starts in the lower left (front) corner and all bytes for a |
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single pixel (e.g. RGB) are stored sequentially in memory. They are not |
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organized in separate layers or channels. |
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The optional mipmap-level are stored directly after the Image |
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data. The dimensions (width/height/depth) are always reduced to 50% |
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of the previous level but stay at least 1. The Image object can hold |
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just a number of levels and must not be complete (end with a 1x1x1 level). |
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If there are any additional mipmap-levels defined, OpenSG will use |
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the data turing the texture-upload process. |
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If the image does not contain mipmap levels, which is true in |
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most cases, OpenSG will use OpenGL functions to create the level |
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direclty as OpenGL objects. The System will not change the |
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image object for rendering. Therefore, the ability to define |
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the mipmap levels is rarely needed but very usefull |
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(e.g. Real-Time Hatching). |
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The pyramid (at least one Level) defines a frame. All frames |
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are stored after each other separately starting with frame 0. |
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If the user loads a multi-frame image and assigns the |
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object to a osg::TextureChunk |
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it is not played automatically as movie. |
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The Application has to set and change the 'current' frame in the |
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TextureChunk. |
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The Image Class implementation does not include Image-Processing |
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functionality, but provides some simple funktions to scale and crop |
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and to set subregions of the data. |
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The system provides loaders and writers for various formats including |
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png, jpeg, tiff, gif and sgi. In addition a specific mtd |
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(multi texture data) reader/writer is included. The mtd file |
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format is a simple platform independent header and binary |
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dump of the Image object data. It is the only format which can |
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hold all field and data properties of the OpenSG Image. |
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The graph loaders (e.g. OSGLoader, VRMLLoader) use the image loaders |
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to fetch the raster data. |
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*/ |
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