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Model Export Question

Started by hahaha Jul 25, 2007 at 2:10 PM 8 replies 900+ views

Original Post

Jul 25, 2007 at 2:10 PM

In 3ds max(any version with MaxScript)how could i properly write an exporter in MaxScript that will export only the vertices and faces properly so it can be easily read and rendered? Thanks

bzroom

138

bzroom

Jul 25, 2007 at 2:17 PM

This article provides some good insight.

Basically, open an existing script and see how it's put together. Then write your script similar to the example one.

hahaha

Author

hahaha

Jul 26, 2007 at 9:15 AM

Thanks that was helpful but it doesnt really talk about rendering your own format. Just in case im using c++, opengl and win32

swiftcoder

Mod

2,296

swiftcoder

Jul 26, 2007 at 9:30 AM

Quote:
Original post by hahaha
Thanks that was helpful but it doesnt really talk about rendering your own format. Just in case im using c++, opengl and win32

Rendering your own format is an entirely different matter. Basically you just load your file into whatever data structures you are using to render in OpenGL (vertex arrays or VBOs, etc.). Specifics depend on how you are rendering, and how your file format is laid out.
I think NeHe has a few articles on model loading, probably worth looking at.

hahaha

Author

hahaha

Jul 26, 2007 at 12:11 PM

If i have these structs:

struct Vertex{   float x,y,z};struct Face{   float x,y,z;}

and this is the vertex and face data loaded into a pointer of the structures

Vertices:-3.23639 0.0 -29.20953.23639 0.0 -29.2095-3.23639 0.0 29.20953.23639 0.0 29.2095-3.23639 11.3347 -29.20953.23639 11.3347 -29.2095-3.23639 11.3347 29.20953.23639 11.3347 29.2095Faces:1.0 4.0 3.04.0 1.0 2.05.0 8.0 6.08.0 5.0 7.01.0 6.0 2.06.0 1.0 5.02.0 8.0 4.08.0 2.0 6.04.0 7.0 3.07.0 4.0 8.03.0 5.0 1.05.0 3.0 7.0

How would i go about rendering it?

swiftcoder

Mod

2,296

swiftcoder

Jul 26, 2007 at 12:16 PM

I am not sure you understand rendering triangles. The vertices are fine, but each Face needs to be a collection of 3 vertices, not 3 floats. After all, a Face is a triangle, and it therefore needs a vertex for each corner. In actual fact, most systems just store 3 indices (offsets) into the array of vertices for each face.

lubby

Jul 26, 2007 at 7:01 PM

As swift coder said, you should change your data structures

Vertices:Vertices 1: -3.23639 0.0 -29.2095Vertices 2: 3.23639 0.0 -29.2095Vertices 3: -3.23639 0.0 29.2095Vertices 4: 3.23639 0.0 29.2095Vertices 5: -3.23639 11.3347 -29.2095Vertices 6: 3.23639 11.3347 -29.2095Vertices 7: -3.23639 11.3347 29.2095Vertices 8: 3.23639 11.3347 29.2095Faces:Face1: 1 4 3Face2: 4 1 2Face3: 5 8 6Face4: 8 5 7Face5: 1 6 2Face6: 6 1 5Face7: 2 8 4Face8: 8 2 6Face9: 4 7 3Face10: 7 4 8Face11: 3 5 1Face12: 5 3 7

Now you can iterate over your faces using the face pointer, using face n(a,b,c) to render a triangle.

// you can do this alot faster using vertex and index arrays, but for immediate rendering this will work.for (int i=1; i<=numFaces; ++i){  vertex1 = Vertices[Faces.a];  vertex2 = Vertices[Faces.b];  vertex3 = Vertices[Faces.c];  DrawTriangle(vertex1, vertex2, vertex3);}

This data is based on a 1 index, You should start working from a 0 index.

0123456789 instead of 123456789(10)

[Edited by - lubby on July 28, 2007 6:01:41 AM]

hahaha

Author

hahaha

Jul 27, 2007 at 9:46 AM

Thanks a lot! Its been puzzling me for days:)

hahaha

Author

hahaha

Jul 29, 2007 at 2:53 AM

Ive come across another problem. Ive written this code for exporting the texture verts:

for i = 1 to NumTVerts do(    tv = GetTVert Mesh i    format "%\n%\n%\n" tv.x tv.y tv.z to:out --file )

when i execute the script with a texture mapped cube i get 3 values(tv.x tv.y tv.z...(either 0.0 or 0.1)) for each face. I can render the faces fine but when it comes to using those texture coords im lost!
Please can someone tell me how to use the texture coords.

Thanks

Pangplast2

Jul 31, 2007 at 12:58 AM

For every face-value (3 for every triangle) you must att two more floats, the (u,v) texture coordinate.

Do not try to use the so called "sticky uv's" method where you put the uv's whith the vertice, this will make it a lot harder to make nice models since two or more triangles MUST share uv coords.

You're still on easystreet now, just wait until you get to bones, vertexgroups, frames and transforms :)

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