How To Read Pixels Of An Input With Nglrender Node?

[user_deleted]

Hi, I'm fairly new to shake, and trying to learn how to write macros.

In this example I'd like to write a macro which I can plug a file-in node into, and it reads the pixels of it and uses an NGLrender node to draw random polygons on only the light areas.

I can get NGLRender to draw random polygons ok (i have some experience with opengl in c++) , but how do I read those pixels?

And, on a more general note, where's a good reference/tutorial for writing macros? Surely there must be one...

Thanks in advance!

[aaron-marine]

well first i would learn just of shake and then start poking around with macros...2 dvds i actually recommend are the gnomon shake dvds (the first one and the scripting/macros one). these will get you a full understanding of shake and push you onto starting macros.

[user_deleted]

Thanks for your reply. Actually I have a pretty decent understanding of the Shake front-end, and I've worked out how to create macros which use existing shake plugins, and how to use the NGLrender node. It's just that one bit I'm stuck on - looking at the RGB value of a certain pixel, and only drawing a polygon if it's above a certain threshold.

Any ideas?

ps Thanks for the suggestion of the gnomon DVDs, but I'm really looking for a detailed reference rather than a tutorial, and preferably something that doesn't cost $70!