How to interpret output position values of Geometry node












1












$begingroup$


I have a simple sphere with a material. And I want to know how understand information the Geometry node gives. I printed this information through OSL shader. Can somebody please explain to me why the position output is roughly (10 10 10), while the object world location is (0 0 30)?



enter image description here



shader Inspector(float input=0,output color debug=0)
{
debug = input;
printf("n");
printf("%f" , debug );
}


enter image description here



enter image description here










share|improve this question











$endgroup$












  • $begingroup$
    How big is your sphere? Is the sphere's origin at its center? Where's the file that shows that problem? Which version of blender are you using? Gosh, so many questions... This is because the Position gives exactly the world coordinates of the point being sampled.
    $endgroup$
    – Secrop
    Jan 27 at 20:37
















1












$begingroup$


I have a simple sphere with a material. And I want to know how understand information the Geometry node gives. I printed this information through OSL shader. Can somebody please explain to me why the position output is roughly (10 10 10), while the object world location is (0 0 30)?



enter image description here



shader Inspector(float input=0,output color debug=0)
{
debug = input;
printf("n");
printf("%f" , debug );
}


enter image description here



enter image description here










share|improve this question











$endgroup$












  • $begingroup$
    How big is your sphere? Is the sphere's origin at its center? Where's the file that shows that problem? Which version of blender are you using? Gosh, so many questions... This is because the Position gives exactly the world coordinates of the point being sampled.
    $endgroup$
    – Secrop
    Jan 27 at 20:37














1












1








1





$begingroup$


I have a simple sphere with a material. And I want to know how understand information the Geometry node gives. I printed this information through OSL shader. Can somebody please explain to me why the position output is roughly (10 10 10), while the object world location is (0 0 30)?



enter image description here



shader Inspector(float input=0,output color debug=0)
{
debug = input;
printf("n");
printf("%f" , debug );
}


enter image description here



enter image description here










share|improve this question











$endgroup$




I have a simple sphere with a material. And I want to know how understand information the Geometry node gives. I printed this information through OSL shader. Can somebody please explain to me why the position output is roughly (10 10 10), while the object world location is (0 0 30)?



enter image description here



shader Inspector(float input=0,output color debug=0)
{
debug = input;
printf("n");
printf("%f" , debug );
}


enter image description here



enter image description here







nodes osl






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Jan 27 at 19:20







Oleksiy Plotnyts'kyy

















asked Jan 27 at 18:58









Oleksiy Plotnyts'kyyOleksiy Plotnyts'kyy

456




456












  • $begingroup$
    How big is your sphere? Is the sphere's origin at its center? Where's the file that shows that problem? Which version of blender are you using? Gosh, so many questions... This is because the Position gives exactly the world coordinates of the point being sampled.
    $endgroup$
    – Secrop
    Jan 27 at 20:37


















  • $begingroup$
    How big is your sphere? Is the sphere's origin at its center? Where's the file that shows that problem? Which version of blender are you using? Gosh, so many questions... This is because the Position gives exactly the world coordinates of the point being sampled.
    $endgroup$
    – Secrop
    Jan 27 at 20:37
















$begingroup$
How big is your sphere? Is the sphere's origin at its center? Where's the file that shows that problem? Which version of blender are you using? Gosh, so many questions... This is because the Position gives exactly the world coordinates of the point being sampled.
$endgroup$
– Secrop
Jan 27 at 20:37




$begingroup$
How big is your sphere? Is the sphere's origin at its center? Where's the file that shows that problem? Which version of blender are you using? Gosh, so many questions... This is because the Position gives exactly the world coordinates of the point being sampled.
$endgroup$
– Secrop
Jan 27 at 20:37










2 Answers
2






active

oldest

votes


















2












$begingroup$

The Position output of the geometry node yields the current shading point (on the surface of your sphere) in World Space. It is the equivalent of the global variable P in OSL.



A lot of the outputs are equvalent to OSL Globals:



Position: point P Position of the point you are shading.



Incoming: The negative of OSL's vector I: The incident ray direction, pointing from the viewing position to the shading position P.



Normal: normal N The surface “Shading” normal of the surface at P.



True Normal: normal Ng The true surface normal at P.(before bump mapping, etc.)



Parametric: float u, v The 2D parametric coordinates of P, as defined for the current object.



The rest as per manual



Your interpretation of point as float seems to have unpredictable results..



I've found you have to use the printed variable in some way to prevent the print from being optimized? away.



shader Inspector(
point input = 0.0,
output color debug = 0.0
)
{
debug = input;
//pointless calculation to prevent printf being optimized away
debug[0] = pow(debug[0],1);
printf("%f n",debug);
}





share|improve this answer









$endgroup$













  • $begingroup$
    Thank you. It seems to be working with vector type as well if we add a pointless calculation. I'm wondering why there is no such optimization with float interpretation.
    $endgroup$
    – Oleksiy Plotnyts'kyy
    Jan 27 at 21:33






  • 1




    $begingroup$
    @OleksiyPlotnyts'kyy maybe because, as Secrop points out, the cast from point to float involves a calculation.. the cast between triples just involves passing the components on, unaltered.
    $endgroup$
    – Robin Betts
    Jan 27 at 21:37



















3












$begingroup$

You're turning a vector into a float. So float=(v[0]+v[1]+v[2])/3.



this will give the correct result:



shader Inspector(float xcomp=0, float ycomp=0, float zcomp=0, output color debug=0)
{
debug = (xcomp+ycomp+zcomp)/3;
printf("n");
printf("%f,%f,%f >> %f" , xcomp, ycomp, zcomp, debug);
}


Use the SeparateXYZ and connect each components to the script.






share|improve this answer











$endgroup$













  • $begingroup$
    It doesn't give any output with vector type now.
    $endgroup$
    – Oleksiy Plotnyts'kyy
    Jan 27 at 20:50












  • $begingroup$
    Ahh.. so that's what the cast from point to float is doing..I couldn't work it out...
    $endgroup$
    – Robin Betts
    Jan 27 at 21:31






  • 2




    $begingroup$
    @OleksiyPlotnyts'kyy, ohh, osl optimizations.. I'm changing the script ;)
    $endgroup$
    – Secrop
    Jan 27 at 21:41











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2 Answers
2






active

oldest

votes








2 Answers
2






active

oldest

votes









active

oldest

votes






active

oldest

votes









2












$begingroup$

The Position output of the geometry node yields the current shading point (on the surface of your sphere) in World Space. It is the equivalent of the global variable P in OSL.



A lot of the outputs are equvalent to OSL Globals:



Position: point P Position of the point you are shading.



Incoming: The negative of OSL's vector I: The incident ray direction, pointing from the viewing position to the shading position P.



Normal: normal N The surface “Shading” normal of the surface at P.



True Normal: normal Ng The true surface normal at P.(before bump mapping, etc.)



Parametric: float u, v The 2D parametric coordinates of P, as defined for the current object.



The rest as per manual



Your interpretation of point as float seems to have unpredictable results..



I've found you have to use the printed variable in some way to prevent the print from being optimized? away.



shader Inspector(
point input = 0.0,
output color debug = 0.0
)
{
debug = input;
//pointless calculation to prevent printf being optimized away
debug[0] = pow(debug[0],1);
printf("%f n",debug);
}





share|improve this answer









$endgroup$













  • $begingroup$
    Thank you. It seems to be working with vector type as well if we add a pointless calculation. I'm wondering why there is no such optimization with float interpretation.
    $endgroup$
    – Oleksiy Plotnyts'kyy
    Jan 27 at 21:33






  • 1




    $begingroup$
    @OleksiyPlotnyts'kyy maybe because, as Secrop points out, the cast from point to float involves a calculation.. the cast between triples just involves passing the components on, unaltered.
    $endgroup$
    – Robin Betts
    Jan 27 at 21:37
















2












$begingroup$

The Position output of the geometry node yields the current shading point (on the surface of your sphere) in World Space. It is the equivalent of the global variable P in OSL.



A lot of the outputs are equvalent to OSL Globals:



Position: point P Position of the point you are shading.



Incoming: The negative of OSL's vector I: The incident ray direction, pointing from the viewing position to the shading position P.



Normal: normal N The surface “Shading” normal of the surface at P.



True Normal: normal Ng The true surface normal at P.(before bump mapping, etc.)



Parametric: float u, v The 2D parametric coordinates of P, as defined for the current object.



The rest as per manual



Your interpretation of point as float seems to have unpredictable results..



I've found you have to use the printed variable in some way to prevent the print from being optimized? away.



shader Inspector(
point input = 0.0,
output color debug = 0.0
)
{
debug = input;
//pointless calculation to prevent printf being optimized away
debug[0] = pow(debug[0],1);
printf("%f n",debug);
}





share|improve this answer









$endgroup$













  • $begingroup$
    Thank you. It seems to be working with vector type as well if we add a pointless calculation. I'm wondering why there is no such optimization with float interpretation.
    $endgroup$
    – Oleksiy Plotnyts'kyy
    Jan 27 at 21:33






  • 1




    $begingroup$
    @OleksiyPlotnyts'kyy maybe because, as Secrop points out, the cast from point to float involves a calculation.. the cast between triples just involves passing the components on, unaltered.
    $endgroup$
    – Robin Betts
    Jan 27 at 21:37














2












2








2





$begingroup$

The Position output of the geometry node yields the current shading point (on the surface of your sphere) in World Space. It is the equivalent of the global variable P in OSL.



A lot of the outputs are equvalent to OSL Globals:



Position: point P Position of the point you are shading.



Incoming: The negative of OSL's vector I: The incident ray direction, pointing from the viewing position to the shading position P.



Normal: normal N The surface “Shading” normal of the surface at P.



True Normal: normal Ng The true surface normal at P.(before bump mapping, etc.)



Parametric: float u, v The 2D parametric coordinates of P, as defined for the current object.



The rest as per manual



Your interpretation of point as float seems to have unpredictable results..



I've found you have to use the printed variable in some way to prevent the print from being optimized? away.



shader Inspector(
point input = 0.0,
output color debug = 0.0
)
{
debug = input;
//pointless calculation to prevent printf being optimized away
debug[0] = pow(debug[0],1);
printf("%f n",debug);
}





share|improve this answer









$endgroup$



The Position output of the geometry node yields the current shading point (on the surface of your sphere) in World Space. It is the equivalent of the global variable P in OSL.



A lot of the outputs are equvalent to OSL Globals:



Position: point P Position of the point you are shading.



Incoming: The negative of OSL's vector I: The incident ray direction, pointing from the viewing position to the shading position P.



Normal: normal N The surface “Shading” normal of the surface at P.



True Normal: normal Ng The true surface normal at P.(before bump mapping, etc.)



Parametric: float u, v The 2D parametric coordinates of P, as defined for the current object.



The rest as per manual



Your interpretation of point as float seems to have unpredictable results..



I've found you have to use the printed variable in some way to prevent the print from being optimized? away.



shader Inspector(
point input = 0.0,
output color debug = 0.0
)
{
debug = input;
//pointless calculation to prevent printf being optimized away
debug[0] = pow(debug[0],1);
printf("%f n",debug);
}






share|improve this answer












share|improve this answer



share|improve this answer










answered Jan 27 at 21:09









Robin BettsRobin Betts

7,2071628




7,2071628












  • $begingroup$
    Thank you. It seems to be working with vector type as well if we add a pointless calculation. I'm wondering why there is no such optimization with float interpretation.
    $endgroup$
    – Oleksiy Plotnyts'kyy
    Jan 27 at 21:33






  • 1




    $begingroup$
    @OleksiyPlotnyts'kyy maybe because, as Secrop points out, the cast from point to float involves a calculation.. the cast between triples just involves passing the components on, unaltered.
    $endgroup$
    – Robin Betts
    Jan 27 at 21:37


















  • $begingroup$
    Thank you. It seems to be working with vector type as well if we add a pointless calculation. I'm wondering why there is no such optimization with float interpretation.
    $endgroup$
    – Oleksiy Plotnyts'kyy
    Jan 27 at 21:33






  • 1




    $begingroup$
    @OleksiyPlotnyts'kyy maybe because, as Secrop points out, the cast from point to float involves a calculation.. the cast between triples just involves passing the components on, unaltered.
    $endgroup$
    – Robin Betts
    Jan 27 at 21:37
















$begingroup$
Thank you. It seems to be working with vector type as well if we add a pointless calculation. I'm wondering why there is no such optimization with float interpretation.
$endgroup$
– Oleksiy Plotnyts'kyy
Jan 27 at 21:33




$begingroup$
Thank you. It seems to be working with vector type as well if we add a pointless calculation. I'm wondering why there is no such optimization with float interpretation.
$endgroup$
– Oleksiy Plotnyts'kyy
Jan 27 at 21:33




1




1




$begingroup$
@OleksiyPlotnyts'kyy maybe because, as Secrop points out, the cast from point to float involves a calculation.. the cast between triples just involves passing the components on, unaltered.
$endgroup$
– Robin Betts
Jan 27 at 21:37




$begingroup$
@OleksiyPlotnyts'kyy maybe because, as Secrop points out, the cast from point to float involves a calculation.. the cast between triples just involves passing the components on, unaltered.
$endgroup$
– Robin Betts
Jan 27 at 21:37













3












$begingroup$

You're turning a vector into a float. So float=(v[0]+v[1]+v[2])/3.



this will give the correct result:



shader Inspector(float xcomp=0, float ycomp=0, float zcomp=0, output color debug=0)
{
debug = (xcomp+ycomp+zcomp)/3;
printf("n");
printf("%f,%f,%f >> %f" , xcomp, ycomp, zcomp, debug);
}


Use the SeparateXYZ and connect each components to the script.






share|improve this answer











$endgroup$













  • $begingroup$
    It doesn't give any output with vector type now.
    $endgroup$
    – Oleksiy Plotnyts'kyy
    Jan 27 at 20:50












  • $begingroup$
    Ahh.. so that's what the cast from point to float is doing..I couldn't work it out...
    $endgroup$
    – Robin Betts
    Jan 27 at 21:31






  • 2




    $begingroup$
    @OleksiyPlotnyts'kyy, ohh, osl optimizations.. I'm changing the script ;)
    $endgroup$
    – Secrop
    Jan 27 at 21:41
















3












$begingroup$

You're turning a vector into a float. So float=(v[0]+v[1]+v[2])/3.



this will give the correct result:



shader Inspector(float xcomp=0, float ycomp=0, float zcomp=0, output color debug=0)
{
debug = (xcomp+ycomp+zcomp)/3;
printf("n");
printf("%f,%f,%f >> %f" , xcomp, ycomp, zcomp, debug);
}


Use the SeparateXYZ and connect each components to the script.






share|improve this answer











$endgroup$













  • $begingroup$
    It doesn't give any output with vector type now.
    $endgroup$
    – Oleksiy Plotnyts'kyy
    Jan 27 at 20:50












  • $begingroup$
    Ahh.. so that's what the cast from point to float is doing..I couldn't work it out...
    $endgroup$
    – Robin Betts
    Jan 27 at 21:31






  • 2




    $begingroup$
    @OleksiyPlotnyts'kyy, ohh, osl optimizations.. I'm changing the script ;)
    $endgroup$
    – Secrop
    Jan 27 at 21:41














3












3








3





$begingroup$

You're turning a vector into a float. So float=(v[0]+v[1]+v[2])/3.



this will give the correct result:



shader Inspector(float xcomp=0, float ycomp=0, float zcomp=0, output color debug=0)
{
debug = (xcomp+ycomp+zcomp)/3;
printf("n");
printf("%f,%f,%f >> %f" , xcomp, ycomp, zcomp, debug);
}


Use the SeparateXYZ and connect each components to the script.






share|improve this answer











$endgroup$



You're turning a vector into a float. So float=(v[0]+v[1]+v[2])/3.



this will give the correct result:



shader Inspector(float xcomp=0, float ycomp=0, float zcomp=0, output color debug=0)
{
debug = (xcomp+ycomp+zcomp)/3;
printf("n");
printf("%f,%f,%f >> %f" , xcomp, ycomp, zcomp, debug);
}


Use the SeparateXYZ and connect each components to the script.







share|improve this answer














share|improve this answer



share|improve this answer








edited Jan 27 at 21:44

























answered Jan 27 at 20:40









SecropSecrop

1,913614




1,913614












  • $begingroup$
    It doesn't give any output with vector type now.
    $endgroup$
    – Oleksiy Plotnyts'kyy
    Jan 27 at 20:50












  • $begingroup$
    Ahh.. so that's what the cast from point to float is doing..I couldn't work it out...
    $endgroup$
    – Robin Betts
    Jan 27 at 21:31






  • 2




    $begingroup$
    @OleksiyPlotnyts'kyy, ohh, osl optimizations.. I'm changing the script ;)
    $endgroup$
    – Secrop
    Jan 27 at 21:41


















  • $begingroup$
    It doesn't give any output with vector type now.
    $endgroup$
    – Oleksiy Plotnyts'kyy
    Jan 27 at 20:50












  • $begingroup$
    Ahh.. so that's what the cast from point to float is doing..I couldn't work it out...
    $endgroup$
    – Robin Betts
    Jan 27 at 21:31






  • 2




    $begingroup$
    @OleksiyPlotnyts'kyy, ohh, osl optimizations.. I'm changing the script ;)
    $endgroup$
    – Secrop
    Jan 27 at 21:41
















$begingroup$
It doesn't give any output with vector type now.
$endgroup$
– Oleksiy Plotnyts'kyy
Jan 27 at 20:50






$begingroup$
It doesn't give any output with vector type now.
$endgroup$
– Oleksiy Plotnyts'kyy
Jan 27 at 20:50














$begingroup$
Ahh.. so that's what the cast from point to float is doing..I couldn't work it out...
$endgroup$
– Robin Betts
Jan 27 at 21:31




$begingroup$
Ahh.. so that's what the cast from point to float is doing..I couldn't work it out...
$endgroup$
– Robin Betts
Jan 27 at 21:31




2




2




$begingroup$
@OleksiyPlotnyts'kyy, ohh, osl optimizations.. I'm changing the script ;)
$endgroup$
– Secrop
Jan 27 at 21:41




$begingroup$
@OleksiyPlotnyts'kyy, ohh, osl optimizations.. I'm changing the script ;)
$endgroup$
– Secrop
Jan 27 at 21:41


















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