Tranforming a model's vertices

[DoomMarine]

I recently have integrated a basic physics/collision system into my game engine. At first it was just AABBs and spheres but now i have found a way to integrate actual model-triangle colision, unfortunately if i scale the model, rotate it, or move it i can not get the vertices of the bounds change accordingly, i have tried getting the positions of the vertices and transforming it by the entities world matrix but that doesnt seem to work and when i debug the vertices positions i get values like infinity or -infinity. I got the position of the vertices through my custom model processor and that seems to work fine, so i believe it has to do with the transformation of the vector3's that i use. Are a model's vertices stored an positioned a certain way so that i can transform there coordinates correctly? If you can please help, thank you.

[Nemo Krad]

I imagine the vert's position is relative to the models position so model.Pos + model.vert.pos should give you the actual position of the vert. Just guessing so I may be well off the mark.

[DoomMarine]

when you say the model position u mean the root bone's transform correct? or are you referring to the mesh's parent bone's one? and if i need to calculate the positions like that how would i integrate scale and rotation?

[Nemo Krad]

I presume you are using the HMEngine and the HMModel object to do this, so I am guessing that you can use the HMModel.Position + the HMModel.Mesh.Verts[v].position to get the correct position of the vert.

Having not seen your code I can only make assumptions...

[DoomMarine]

heres the code i use to move the triangle's vertex's position

Code:

public void RefreshTris(Matrix world)
        {
            Vertex1 = Vector3.Transform(vertstore1, world); 
            Vertex2 = Vector3.Transform(vertstore2, world); 
            Vertex3 = Vector3.Transform(vertstore3, world); 
        }

[Nemo Krad]

Say you arnt giving much away there....

It looks like you could do with doing this

Code:

    Vertex1 = Vector3.Transform(this.Position + vertstore1, world);

Again, this is an asumption....

[DoomMarine]

sry bout not giving much away havent decided if i wanted to show everything yet, but the world matrix that i use is made like this

Code:

RefreshTris( RotationMatrix * Matrix.CreateScale(Scaling) * Matrix.CreateTranslation(position), position);

im wondering if thats how it should have been made

[Nemo Krad]

hmm the world matrix looks odd to me.

Mike uses Scale * Rotation * Position
You are using Rotation * Scale * Position

maybe this is your issue??

[DoomMarine]

ive tried the scale *rotation * position but that doesnt seem to be making a difference, i wonder if it is how i get the vertices positions that my be the problem. To get the vertices positions i have a binary reader read the models data from a memory stream, should i be using something else?

[Nemo Krad]

Not that I know where, but in the Refresh don't they give you access to the mesh verts as standard now?

[DoomMarine]

wow, lol, i did not know that, ill check that out now

[DoomMarine]

it doesnt seem to make a difference i am still gettin screwed up collision but the tri's points seem to be fine, it might have something to do with my triangles collision so ill check that out next

[DoomMarine]

not the collision either so it must be the transformation of the vertices, are the vertices already transofrm to the mesh's parent bone transform?

[Nemo Krad]

I don't know, one way to find out would be to remove the transform code you have and try it with out...

[DoomMarine]

now the vertices positions seem to screw up the collision, i am getting very strange results from it, how exactly are you supposed to get the vertices data from the model? i used the getdata function for the index and vertex buffers but i wasnt to sure on how to get the total amount for the array that i use to store the data, if you can help with this it will be appreciated