MTV3D65.TV_COLLISIONRESULT & UV

[newborn]

It seems that MTV3D65.TV_COLLISIONRESULT sometimes returns negative u/v values

[Zaknafein]

UV coordinates are [0, 1[, so a -0,25 U coordinate is equal to 0,75. You can bring them back in the right interval pretty easily.

[newborn]

hum.. okay, I also get U/V > 1 as well, like 1.3

Would that be 0.7 ?

[GD]

If it's like Zak says then it should be 0.3 hmm

Code:

realValue = value - math.floor(value)

[JukkaKevät]

This is no bug, this is how uv's work. U or V more than one or less than zero means the texture is tiled.

[SylvainTV]

Well do you mean UV or TexUV thats two different things.

If UV ( U V in barycentric coordinates of the triangle ) is negative, there is a problem I think
If it's TexUV, no problem, it's normal, it just interpolates the texture coordinates of the mesh.

[newborn]

I think we have a workaround for this, suggested by Zak:

while(u>1)u--
while(u<0)u++
while(v>1)v--
while(v<0)v++

it's just weird... I understand what you mean JukkaKevät, but when TV3D returns a UV out of bounds, its hard to figure out the texture's pixel where the collision happened if you're trying to create a shadowmap (for instance)

[JukkaKevät]

You will run into problems if you are trying to bake shadows to an unwrap which is out of 0<->1. If the model which you are trying to shadow map does not have a correct unwrap (each part of the surface should be unique) then you will rewrite parts of the texture in the process.

[GD]

while(u>1)u--
while(u<0)u++
while(v>1)v--
while(v<0)v++

Come on...

Code:

u = u - math.floor(u)
v = v - math.floor(v)

[SylvainTV]

Well TV interpolates with what is in the model
There could be some situations when you could need UV < 0 or UV > 1.
Think tiling for example.

but yea
u = u - math.floor(u)
v = v - math.floor(v)
works fine

[Zaknafein]

Come on...

Hahah, mea culpa. I didn't think about this much at all.

[newborn]

Come on...

Code:

u = u - math.floor(u)
v = v - math.floor(v)

Well this clearly shows the difference between a hobbyist who's still learning and someone who knows his stuff...

Thanks for the tip

edit: wouldn't this work as well?

        fU -= Math.Floor(fU)
        fV -= Math.Floor(fV)

[newborn]

If the model which you are trying to shadow map does not have a correct unwrap (each part of the surface should be unique) then you will rewrite parts of the texture in the process.

Yup, and my artist is renown to do that