6 replies to this topic

[chenbin_osu]

Hello,

I'm trying to think of a good and efficient way of rendering "selection" boxes on a model in a 3D world.

As an example, here's a screenshot of what I want:



The model on the top has a green target around it. This is what I want to render.

Any ideas are apprecaited. Thanks!

[anubis]

Render a billboarded quad over the target. You should be able to extract the necessary size from the bounding box of the target.

[bladder]

Another way to do it: You can project the 3D world coordinats of your model to screen space - the opposite of picking. You can use this x,y point in screen space and just render a 2D box around the point in screen sspace. AFAIK, that's what is usually done because you can still see the target box even when an object goes behind something (in the games I can recall right now)

[Methulah]

Coolio. How did that funky effect in Warhammer 40K work out where when the units went around buildings, a coloured sillouhette of them showed up? That effect rocked, and I was wondering if it is possible/easy to do in DirectX, in particular Source Engine?

[zavie]

Can you give some link to a screenshot? I have never seen this game, but if I understand what you mean, I think I have an idea...

[dj]

when you render to screen space, how would you be able to find the x,y?

[zavie]

Multiply the object vector by the modelview matrix, and then by the projection matrix.
:-)