Change projection orientation

[yokotsumo]

From what I understand, the projection is made in parallel with the normal at the intersection point. Is there an easy way to make the projection in parallel with the vector from the mouse coordinate to the intersection point (perpendicular to the 2D canvas - do not know if it is clear?) ?

[spite]

The decal is created intersecting a box volume with a specific direction. That direction it's usually the normal of the surface in the point where the decal is to be projected, but it can be any vector. In the demo http://www.clicktorelease.com/code/decal-splatter/ you can switch "normal to surface" or "camera to surface". I think that's what you are asking, right?

[yokotsumo]

Yes, exactly. My mistake for this question.
I have another question, is there a CPU-efficient way to manage the z-depth. In each decals demo I have seen, the projection is done on all the vertices inside the box. What I mean is not to project on elements that are not 'visible' inside the box (opposite sides, far sides (not lowest z), etc.) from the camera? I though of a few possibilities but it is very CPU-intensive.