Maxscript - scripting Vertex Colour fails unless I do a manual assign once

Rick Stirling

Cross posting from the maxscript forum on CG Talk


I've written a script that takes lighting from a skylight and bakes ambient occlusion in the (any) vertex colour channel of a mesh.

I can't seen a problem with the script, however when I first run it I always get a pure black bake on the mesh UNLESS I manually assign the bake using the Assign Vertex Colours tool in the tool panel. After this the script works perfectly. I only need to do this once per max session, I can then load any model that I want, rebuild my lighting, pretty much do anything in max and the scripted assign vertex colours works.


The (stripped down) command to assign the colours is simple enough:

AssignVertexColors.ApplyNodes $ vertexPaint:$.modifiers[#VertexPaint]


Can anyone help me understand why I need to manually run the bake once per session? Is it just a max foible?

renderhjs

I recently mixed a script that uses vertex colors and then bake it using RTT - and it works in just 1 click. It is based on this script:
http://www.scriptspot.com/3ds-max/pits-peaks

the order of things is something like this:

for i = 1 to $.numVerts do(
	local colr = color (random 0 255) (random 0 255) (random 0 255);
	setVertColor $ i colr;-- apply vertex color
)
$.showVertexColors = true;
$.vertexColorsShaded = false;	
update $;

hope that snippet gets you further

Rick Stirling

Max has died at home, so I can't test if that 'update $' line will do the trick.

I don't bake to a texture, I bake the AO into a vertex colour channel.

I think it's just an initialisation thing, because after I manually assign the vertex colours once to any mesh in the scene the script works perfectly after that, and works until I next open max.