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mike74

default 3d view

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I would like to make a program to view 3ds files. However, many of the files do not contain a camera definition. Thus, it seems necessary to create a default view. Does anyone know what the standard procedure for doing so is? My current idea for a default view is to compute the centroid by averaging all the points. Then, I will translate by the opposite of the centroid (to essentially move the centroid to 0). Then I will scale everything by the maximum distance from the centroid to make the maximum distance 1. Then I will push everything back along the z axis by -2. Here's some pseudocode: centroidx = (sum of all x values) / (number of points); centroidy = (sum of all y values) / (number of points); centroidz = (sum of all z values) / (number of points); maxdist = maximumdist(centroidx, centroidy, centroidz, points); glTranslatef(0, 0, -2); glScale(1/maxdist); glTranslatef(-centroidx, -centroidy, -centroidz); drawpoints(); Does this seem reasonable? Mike C. http://www.coolgroups.com/zoomer/

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There is no need to scale. Just place the model at the position where its bounding sphere fits in the window. The distance is computed like this:

z = radius / sin( fov/2 )

So, you code will look something like this:
    glTranslatef( -centroidx, -centroidy, -centroidz );
glTranslatef( 0.0f, 0.0f, -maxdist / sinf( fov * 0.5f ) );

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I thought of this, but what if it's outside the viewing frustum? That's why I opted to scale instead.

Mike C.
http://www.coolgroups.com/zoomer/

Quote:
Original post by JohnBolton
There is no need to scale. Just place the model at the position where its bounding sphere fits in the window. The distance is computed like this:

z = radius / sin( fov/2 )

So, you code will look something like this:
    glTranslatef( -centroidx, -centroidy, -centroidz );
glTranslatef( 0.0f, 0.0f, -maxdist / sinf( fov * 0.5f ) );


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