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giuseppe500
05-22-2012, 04:01 AM
hello.
I'm trying to create an ifc importer(an architectural format).
My problems are at the start:
1)i must use matrixes and vectors , how is knows :
1a)the order of multiplication of the matrix for vector?
1b)the coordinate system (left handed or right handed)?
1c)the matrixes are row major or column major?

after ,

if i have a different axis system , for example in my program i have y on top ,x on left and z inside and in the ifc i have z on top y on left and x inside , how i can import the geometrics items for have the same orientation and correct placing?

ps. the used api is opengl
thanks.

tonyo_au
05-22-2012, 05:46 AM
You can use a matrix to convert from one axis system to another. But if you intend to render using OpenGL the simplest might be to convert each ifc vertex as you read it into OpenGL standard format. That way any OpenGL code examples you look at will be directly useable.

(I assume inside is the positive values)
ifc -> OpenGL standard axes
so ifc -> opengl
x -> -z
y -> -x
z -> y

for ifc -> your program axes
x -> z
y -> x
z -> y