Iris ! O astre flamboyant, rayonnant sur le monde Saurais-tu meme en toi lover toutes les directions Que jamais, autre que trahie par quelque reflexion Jamais, telle qu'a l'origine. n'entrera dans ta ronde
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To fully understand the shape of metallic structures, designers need to take into account the reflections from the surrounding environment. In the AEC market, where oil platforms are designed, this type of visualization often prevents very costly mistakes. This is the reason why CadCentre (Cambridge, UK) asked the Core Technology Group of Silicon Graphics (Cortaillod, Switzerland), to integrate the latest techniques of "Texture Mapping" into their application Review - PDMS. Chosen from among the projects undertaken by this partnership, an optimized version of the "Environment Mapping" technique is presented here. This technique is based principally on the calculation of a 360 degrees Environment Map, taken from the centre of the object : for each point on the surface of this object, the appropriate reflected color is computed using this map as a lookup table for the surface normal at this point. The Environment Map needs to be updated any time a modification of the environment occurs; this data processing involves non-trivial mathematics. When using a video source to integrate all or part of an existing environment, it is thus necessary to recalculate the Environment Map for each frame. By providing its user with the ability to acquire, process and interactively visualize scientific data in real time, the Silicon Graphics architecture ranks second to none in the AEC/CAD marketplace. At this stage, we just draw the environment map, in the middle of the view. In a real application, we would load it into the Texture memory and use it as a GL_SPHERE_MAP on any object located inside of this environment. This "sphere-map" is a 360 degrees view of the surrounding environment: the rendering of a sphere would only let you see a 180 degrees view !
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The EnvMap program has been compiled and tested
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- IRIX 6.2 |
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It is also expected to compile and run on the
following systems, but has NOT BEEN TESTED: |
- Reality Engine (5.3 with OpenGL Extensions Patch 918 (successor to 154)) |
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* * * The EnvMap binary included on v6.1 of the Developer Toolbox was generated on an IRIX 6.2 Indigo² IMPACT system. In order to recompile you must install the GLUT 3.0 software, included on this v6.1 Toolbox, onto your own system. The inst images or tardist file can be found in
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