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Translating Obj face data into useful D3D10 rendering data

Started by rofseek Mar 30, 2010 at 9:29 AM 1 replies 1.3k views

Original Post

Mar 30, 2010 at 9:29 AM

Assuming the following definition of a 10cm^3 cube:

v  -1.1556 0.0000 0.6891
v  -1.1556 0.0000 -3.2479
v  2.7814 0.0000 -3.2479
v  2.7814 0.0000 0.6891
v  -1.1556 3.9370 0.6891
v  2.7814 3.9370 0.6891
v  2.7814 3.9370 -3.2479
v  -1.1556 3.9370 -3.2479
# 8 vertices

vn 0.0000 -1.0000 -0.0000
vn 0.0000 1.0000 -0.0000
vn 0.0000 0.0000 1.0000
vn 1.0000 0.0000 -0.0000
vn 0.0000 0.0000 -1.0000
vn -1.0000 0.0000 -0.0000
# 6 vertex normals

vt 1.0000 0.0000 0.0000
vt 1.0000 1.0000 0.0000
vt 0.0000 1.0000 0.0000
vt 0.0000 0.0000 0.0000
# 4 texture coords

g Box01
usemtl wire_229154215
s 2
f 1/1/1 2/2/1 3/3/1 4/4/1 
s 4
f 5/4/2 6/1/2 7/2/2 8/3/2 
s 8
f 1/4/3 4/1/3 6/2/3 5/3/3 
s 16
f 4/4/4 3/1/4 7/2/4 6/3/4 
s 32
f 3/4/5 2/1/5 8/2/5 7/3/5 
s 64
f 2/4/6 1/1/6 5/2/6 8/3/6 
# 6 polygons

How can the face data be processed/translated into useful information for rendering?

Guthur

Mar 30, 2010 at 10:08 AM

The easy way is just use a model loader lib; there will be many of them I'd imagine, they will import and compile all the information and should be well tested.

I'd personally use assimp to import from a wide variety of formats then produce my own format with only the information I require.

But you could also just get a specific .obj loader.

Dunge

Mar 30, 2010 at 11:13 AM

obj format for the "f" face data is defined as:

f v1[/vt1][/vn1] v2[/vt2][/vn2] v3[/vt3][/vn3] ...

So a face is a triangle, composed of three vertex position, uv texture and vertex normal. Since some of the values could be duplicate, it's indexed. DirectX offer vertexbuffer and indexbuffer just for that, look it up.

http://msdn.microsoft.com/en-us/library/bb205130%28VS.85%29.aspx

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