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Guest Anonymous Poster

3D for ISO

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If you're making your own 3D rendering engine there's no reason you have to make it use a perspective projection. You could just as easily (actually more easily) make it use orthagonal projection.

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usually to show perspective you divide the x and y by the z coordinate. What you want is just to throw out the z so far away things are just as big as nearby things.

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Guest Anonymous Poster
Could someone show a formula for calculating a matrix for an orthogonal projection? I've looked everywhere and keep on coming up with map projections =) Thanks...

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Guest Anonymous Poster
This post is in the Iso section but it also files under graphics programming so....

How is it possible to use 3D to render a isometric world correctly when perspective always messes things up (such worlds as Alpha Centauri and Railroad Tycoon 2)?

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From the OpenGL docs [with minor modifications]:

The orthogonal matrix corresponds to:

a 0 0 tx
0 b 0 ty
0 0 c tz
0 0 0 1

where

a = 2/( right - left )
b = 2/( top - bottom )
c = -2/( far - near )
tx = -(right+left)/(right-left)
ty = -(top+bottom)/(top-bottom)
tz = -(far+near)/(far-near)

Note: OpenGL uses the right hand convention and a column-major matrix format.

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