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j00hi

Member Since 13 Sep 2012
Offline Last Active Sep 29 2012 02:46 AM

Posts I've Made

In Topic: How to implement Texture Projectors (projective texture mapping) like in Unity

21 September 2012 - 07:56 AM

I've asked in the Unity forum, how they have implemented projectors.

Here's the question:
http://answers.unity3d.com/questions/319622/what-is-the-algorithm-used-behind-projectors.html

There are some very interesting comments and results.

In Topic: How to implement Texture Projectors (projective texture mapping) like in Unity

14 September 2012 - 02:53 AM

Oh nice! Then I guess I should take a look into that technique.

Yes, I'm mainly developing for mobiles. And in my Unity projects, I'm using projectors a lot.
I use them for:
-) grenade craters on the terrain, after a grenade exploded
-) blob shadows for enemies
-) hexagonal grid projection onto the terrain (using a repeating texture and an orthogonal projector)

Basically I could use an orthogonal projector for all those, but I want to have the possibility of perspective projection, too.

In Topic: How to implement Texture Projectors (projective texture mapping) like in Unity

13 September 2012 - 09:34 AM

Hmm, I have also thought about those two possibilities, but I think, there are problems with both of them:

1) tri-overlay and use alpha blending:
That wouldn't represent underlying geometry exactly, would it?
(The Unity projectors are exactly on the geometry, every pixel)

2) Precalculate the texture (on-the-fly):
Would this be even possible in realtime? If there were lots of objects and lots of projectors, I think that would have a huge impact on performance.
Furthermore, I think that wouldn't work for every texture-combination. The terrain could have a repeating grass texture, and the projector could be a non-repeating texture => how would you precalculate those? I doubt that would be possible in a fast/easy way.

In Topic: How to implement Texture Projectors (projective texture mapping) like in Unity

13 September 2012 - 05:56 AM

Thanks for the link!

I don't think that Unity is using a deferred renderer, because those projectors work on mobile platforms (iOS, Android) as well. According to the license comparison (http://unity3d.com/unity/licenses) deferred rendering is not supported on mobile at all.

Maybe there is another approach which isn't based upon a deferred renderer?

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