On Tue, 22 May 2007, Weitz, Andrew C. wrote:
> Hi,
>
>
>
> I'm having transparency issues that I thought were solvable with a
> TexEnvCombine. However, I cannot figure out the solution.
>
>
>
> I have a scene in which I'm projecting a texture onto terrain that is
> already textured. The terrain is generated with the createBase()
> function in the osgShadowTexture example. I'm projecting another
> texture onto that terrain via a TexGenNode. My projected texture only
> encompasses a small portion of the entire terrain.
>
>
>
> I'd like to control the opacity of my projected texture. I tried doing
> so with a TexEnvCombine. This seems to work correctly, except that it
> blends the textures on the entire terrain-not just the area where my
> texture is projected. The terrain surrounding the projection area gets
> blended with my projected texture's border color. This makes me think
> that a solution would be to make my projected texture's border
> transparent. However, I can't figure out how. Relevant code is
> below...
>
>
>
> Is there a way I can only control the opacity/blending only in the area
> where my texture is projected?
>
>
>
> Thank you,
>
> Andrew
>
>
>
>
>
> // Create the terrain (this uses a texture unit of 0)
>
> osg::ref_ptr<osg::Geode> shadowed = createBase( osg::Vec3(0, 0, 0), 50
> );
>
>
>
> // Create the TexGenNode
>
> osg::ref_ptr<osg::TexGenNode> texgenNode = new osg::TexGenNode;
>
> texgenNode->setTextureUnit( 1 );
>
> texgenNode->getTexGen()->setMode( osg::TexGen::EYE_LINEAR );
>
> texgenNode->getTexGen()->setPlanesFromMatrix( blah blah blah );
>
>
>
> // Create the decorator stateset with the projected texture
>
> osg::ref_ptr<osg::StateSet> stateset = new osg::StateSet;
>
> texture->setInternalFormat( GL_RGB/*A*/ );
>
> texture->setWrap( osg::Texture2D::WRAP_S,
> osg::Texture2D::CLAMP_TO_BORDER );
>
> texture->setWrap( osg::Texture2D::WRAP_T,
> osg::Texture2D::CLAMP_TO_BORDER );
>
> texture->setBorderColor( osg::Vec4( 1.0, 0.0, 0.0, 1.0 ));
>
Try setting the border color to something transparent, ie.
osg::Vec4( 1.0, 0.0, 0.0, 0.0 )
> stateset->setTextureAttributeAndModes( 1, texture.get(),
> osg::StateAttribute::ON );
>
> stateset->setTextureMode( texture_unit, GL_TEXTURE_GEN_S,
> osg::StateAttribute::ON );
>
> stateset->setTextureMode( texture_unit, GL_TEXTURE_GEN_T,
> osg::StateAttribute::ON );
>
>
>
> // Create the TexEnvCombine
>
> osg::ref_ptr<osg::TexEnvCombine> tec = new osg::TexEnvCombine();
>
> tec->setCombine_RGB(osg::TexEnvCombine::INTERPOLATE);
>
> tec->setSource0_RGB(osg::TexEnvCombine::TEXTURE);
>
> tec->setSource1_RGB(osg::TexEnvCombine::PREVIOUS);
>
> tec->setOperand0_RGB(osg::TexEnvCombine::SRC_COLOR);
>
> tec->setOperand1_RGB(osg::TexEnvCombine::SRC_COLOR);
>
> tec->setConstantColor(osg::Vec4(0.5, 0.5, 0.5, 0.5 ));
>
> stateset->setTextureAttributeAndModes(1, tec.get(),
> osg::StateAttribute::ON );
>
>
>
>
>
>
>
>
---
In October 1997, three computer lab staffers
disappeared from the server room while debugging
a mysterious router problem.
One year later, their packet logs were found...
The Blair Switch Project
--------------------
| Don Tidrow |
| Vis-Sim Geek |
--------------------
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