Math question: How to project a rotation in plane?

[Auradrummer]

Hello guys!

I'm with a little problem here:
I need to cast downward three rays from an object. The problem I'm facing is to calculate the destination point to be exactly under the origin point, even if the object turns. To do this, I think I need to project a rotation matrix in the plane (like a mid day sun shadow). How can I do this?

Thanks.

[JernejL]

Hello guys!

I'm with a little problem here:
I need to cast downward three rays from an object. The problem I'm facing is to calculate the destination point to be exactly under the origin point, even if the object turns. To do this, I think I need to project a rotation matrix in the plane (like a mid day sun shadow). How can I do this?

Thanks.

You just take the origin point as ray origin, and the target point from local space transformed with the object's newton body matrix as target point.

[Auradrummer]

Hi Delfi,

Doesn't work. This is how I'm using. But, I want that the ray is always verical to the global space, not to the caster. Like the ray is dropping from the body, got it? IF the body inclinates, the ray cannot inclinate. I tried to not transform, only add it to the matrix.m_posit, but in this case I miss the heading of the objects.

[JernejL]

Hi Delfi,

Doesn't work. This is how I'm using. But, I want that the ray is always verical to the global space, not to the caster. Like the ray is dropping from the body, got it? IF the body inclinates, the ray cannot inclinate. I tried to not transform, only add it to the matrix.m_posit, but in this case I miss the heading of the objects.

If you want the ray to always be aligned by gravity, then what is the problem? and what has heading to do with raycasts? rays don't have any heading if they "follow the gravity".

[Auradrummer]

Delfi,

Yesterday this problem seemed to be so difficult. I spent ours before asking for help. Today, when I woke, I saw how stupid is it. Is only to subtract some value in Y that the ray goes down as I wanted.

Sorry to post so stupid question! But this happens with everyone (I hope)!

[JernejL]

no problem, i'm happy you solved it