Linear control matrix grid in nurbs

Aug 1, 2010 at 7:35pm

Linear control matrix grid in nurbs

I hope my english is comprehensible…

I need to keystone a video on a curved surface. The classic 4 corner pin keystoning isn’t suitable for my needs, since I also need to correct the distortion of the plane on the projection surface.

I thought that a nurb with a video-texture would have been a solution so I downloaded the Jitter Recipes Book n°2 and messed with the Recipe 18: Manipulator, to learn the basics.

The patch is almost perfect, but the control point grid generated by the message exprfill “snorm[0]” is not a linear grid. You could see it by activating the “draw as mesh” toggle. It’s a grid that is somewhat larger on the sides and narrower at centre. In fact, the attached video texture has a slight barrel distortion.

I tried to change the message, but I couldn’t figure out what is the right function to generate a simple equidistant grid of control points. Can someone help me?

My patch is very similar to Recipe 18, but, here it is anyway:

– Pasted Max Patch, click to expand. –
#51598
Aug 1, 2010 at 9:52pm

Hello,
When you send order 1 1 it looks equidistant, doesn’t it ?
cheers
Hubert

#185107
Aug 1, 2010 at 9:52pm

I’m sorry, adding the message ctlshow $1 made me realize that the control matrix is perfectly linear. The problem is in the mesh itself and how the video texture is applied to it.
Some advice?

#185108
Aug 1, 2010 at 9:53pm

Yes, when I send order 1 1 it looks equidistant… I have a lot to learn, thanks…

#185109

You must be logged in to reply to this topic.