Re: [osg-users] get a Texel from an osg::Image

[Jeremy Moles]

On Fri, 2008-07-11 at 11:17 +, ka Ming wrote:
> Hi,
> is there any possibility to get, for example the rgb value, out of an
> osg::Image.
> data() returns only an unsigned char*
> I need or I want an vec3 or with alpha value a vec4 as retrun value.
> Is there any solution.
> ming

osgWidget has a method:

osgWidget::Widget::getImageColorAtXY()

...that does something like this if you want to see how I did it.

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Re: [osg-users] get a Texel from an osg::Image

[David Spilling]

Ming,

So long as you know that the image format is GL_RGBA8, and 2D, you can do
something like:

osg::Vec4 returnColour(int row, int col)
{
unsigned char*  pSrc  = (unsigned char*)  image->data(row,col);
float r = (float) *pSrc++/255.0f;
float g = (float) *pSrc++/255.0f;
float b = (float) *pSrc++/255.0f;
float a = (float) *pSrc++/255.0f;
return osg::Vec4(r,g,b,a);
}

If you are not in control of the image's format then you should check
whether it is RGB or RGBA before trying to get alpha, and also whether it is
RGBA8 and not (for example) RGBA16F, or RGBA32F, or something slighly more
esoteric.

Hope that helps,

David
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[osg-users] get a Texel from an osg::Image

[ka Ming]

Hi,
is there any possibility to get, for example the rgb value, out of an 
osg::Image.
data() returns only an unsigned char*
I need or I want an vec3 or with alpha value a vec4 as retrun value.
Is there any solution.
ming



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