Re: [osg-users] Fix for transparent materials in COLLADA DAE reader

[steven_thomas]

Roger, your implementation looks good to me. As you suspected, you do need to check ctt->getColor() for null before you use it. There might be a <param> or <texture> there instead. The three are mutually exclusive. In theory the <transparency> value should be combined with the <transparent> element regardless of whether or not the <transparent> is a <texture>, <param>, or <color> (<color> is by far the most common), but I'm not sure how feasible that is in fixed-function OpenGL. What you have should work for the great majority of COLLADA data you'll encounter in the wild. Roger James wrote: I have been doing some work on fixing the handling of the “transparent” and “transparency” types in the Collada reader. I have come up with the following piece of code which appears to work reasonably well for the test cases I have. It would be great if someone with a more intimate knowledge of Collada  than mine (hopefully Mike or Marcus) could look this over and see if I have interpreted the remarks in the Collada 1.4.1 release notes and various collada forum threads correctly. I must admit I found it somewhat confusing!   I left this post as HTML to try and retain some formatting. (OT – if anyone know how to stop Outlook plain text mode wrapping at column 80 please let me know!)     osg::StateAttribute *daeReader::processTransparencySettings( domCommon_transparent_type *ctt,  domCommon_float_or_param_type *pTransparency, osg::StateSet *ss ) {       if (NULL == ctt && NULL == pTransparency)             return NULL;       if (ctt && ctt->getTexture() != NULL)     {             osg::StateAttribute *sa = NULL;         sa = processTexture( ctt->getTexture() );         osg::BlendFunc *bf = new osg::BlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );         ss->setAttribute( bf );         ss->setMode( GL_BLEND, GL_TRUE );         ss->setRenderingHint( osg::StateSet::TRANSPARENT_BIN );         ss->setRenderBinDetails( 10, "DepthSortedBin" );             return sa;     }           // Fix up defaults acoording to 1.4.1 release notes       domFloat4 f4;       domFx_opaque_enum Opaque = FX_OPAQUE_ENUM_A_ONE;       if (NULL == ctt)       {             f4.append(0.0f);             f4.append(0.0f);             f4.append(0.0f);             f4.append(1.0f);       }       else       {             Opaque = ctt->getOpaque();             // I wonder if I should do a test like this here DOES ANYBODY KNOW?             //if (NULL == ctt->getColor().cast())             f4 = ctt->getColor()->getValue();       }         domFloat Transparency;       if (NULL == pTransparency)             Transparency = 1.0f;       else       {             Transparency = pTransparency->getFloat()->getValue();             if (m_AuthoringTool == AuthoringTool::GOOGLE_SKETCHUP) // Google back to front support                   Transparency = 1.0f - Transparency;       }       osg::BlendColor *bc = new osg::BlendColor();     bc->setConstantColor(osg::Vec4( f4[0] * Transparency, f4[1] * Transparency, f4[2] * Transparency, f4[3] * Transparency ));     ss->setAttribute( bc );       osg::BlendFunc *bf;       if (FX_OPAQUE_ENUM_A_ONE == Opaque)             bf = new osg::BlendFunc(GL_CONSTANT_ALPHA, GL_ONE_MINUS_CONSTANT_ALPHA);       else             bf = new osg::BlendFunc(GL_ONE_MINUS_CONSTANT_COLOR, GL_CONSTANT_COLOR);       ss->setAttribute( bf );     ss->setMode( GL_BLEND, GL_TRUE );         if (FX_OPAQUE_ENUM_A_ONE == Opaque)       {             if (Transparency  * f4[3] > 0.99f)                   return NULL; // Material is really opaque so dont put it in the transparent bin       }       else       {             if ((Transparency  * f4[0] < 0.01f) &&                   (Transparency  * f4[1] < 0.01f) &&                   (Transparency  * f4[2] < 0.01f) &&                   (Transparency  * f4[3] < 0.01f))                   return NULL; // Material is really opaque so dont put it in the transparent bin       }       ss->setRenderingHint( osg::StateSet::TRANSPARENT_BIN );     ss->setRenderBinDetails( 10, "DepthSortedBin" );       return NULL; }   _______________________________________________ osg-users mailing list osg-users@openscenegraph.net http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/

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