material not render with merge

[Ezz]

Hello dear Houdini-Folks.

So here I am again with a new challenge :-)

I am in full progress of learning this wonderfull yet difficult software.

I have a scene where I merge to materials in a MERGE-SOP. Somehow

one of the materials will not render.

Basicly Its a logo ( my girlfriends name ) that disolves into flowers.

Both materials get an Alpha-value from a POP-NET. This method was

kindly showned to me by OLD SCHOOL.

My lack of understanding VEX must somehow mess things up.

So If someone could help me a bit down the road I will very happy :-)

Erik

disolve.hipnc

[old school]

You have point normals on your disintegrating logo but no normals on your flowers.

The Merge SOP does't know how to build point normals so your second input flowers receive point normals of 0,0,0 which mean they don't get lit. Lighting is based on surface normals and the light direction. Zero normals means zero light.

The fix is easy. Either compute point Normals with a Point SOP or a Facet SOP after the material_flower SOP or add a Point SOP after the material _prim and choose the No Normal option to remove them.

The basic rule with the Merge SOP is if one input has an attribute that doesn't exist on any other inputs, those other geometries get assigned that attribute but set to zero. Color Cd has the same issue. If one input has Cd color attributes, the other inputs without Cd get 0,0,0 or black.

-jeff

[Ezz]

Hi Old School.

Thank you so much for helping me once again! Its much appriciated.

It works now beautifully and it makes sense with the merge-node and the attributtes feed into it.

So my wheels are out of the mud ready to race on with Houdini :-)

Thanks again

Erik