15 replies to this topic

[Medo3337]

Hi everyone,

How do I calculate the billboard transformation to make a bullet hole at certain point on a mesh?

The mesh can be complicated (building, vehicle, interiors, etc...), so I'm looking for a way to place the bullet hole billboard on the mesh at the point the player is shooting.

[stc.5421]

hey
you can use a decal system like this

http://www.humus.name/3D/VolumeDecals.zip

[mk1x86]

You can also take a look at this one:
http://blog.wolfire.com/2009/06/how-to-project-decals/

[Medo3337]

I'm not looking to use shader now, is there is anyway to calculate the billboard position and vertex position information to set the billboard transformation according to that?

[stc.5421]

1- "p" is your intersected point

2- "v1,v2,v3" are your intersected face vertices

3- "N" is your face normal or you can calculate it from your vertices
{
A = v2 - v1
B = v3 - v1
N = normalize( cross( A , B ) )
}

4- Calculate your Up and Right vector
{
up = normalize( p - v1 )
right = cross( up , N )
}

5- "Q1,Q2,Q3,Q4" are your Quad vertices and can calculate like this
{
Q1 = p + up * scale
Q2 = p - up * scale
Q3 = p + right * scale
Q4 = p - right * scale
}

Edited by stc.5421, 06 December 2012 - 09:20 AM.

[Medo3337]

@stc.5421: What about the billboard rotation?

[stc.5421]

You don't need it , that create a quad align to the mesh face .

Edited by stc.5421, 07 December 2012 - 02:23 AM.

[Anddos]

this is a d3d10 sample, why is do you give him d3d10 code?, plus its not even the full source code...

[Medo3337]

@stc.5421: I have LPD3DXMESH, how can I calculate the face normal, face vertices?

[stc.5421]

Did you do intersect to your mesh by D3DXIntersect function?

[Medo3337]

No, I'm using Bullet Physics Raytest.

[stc.5421]

And what's your problem right now?
Can you get information from RayResultCallback ?

[Medo3337]

Can I get the face normal and face vertices from ClosestRayResultCallback? I'm trying to get them to use the example you gave above.

[stc.5421]

Sorry for delay , use this:

http://bulletphysics.org/Bullet/phpBB3/download/file.php?id=588

Edited by stc.5421, 08 December 2012 - 12:32 PM.

[Medo3337]

Hi stc.5421,

I will be using D3DXIntersect() instead, how can I get the intersected face vertices when I use D3DXIntersect()?

Also, where normalize() and cross() are located? Do you mean btVector3::normalize() and btVector3::cross()?

Edited by Medo3337, 09 December 2012 - 08:26 PM.

[Medo3337]

Any update guys? I still didn't resolve the issue.