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Helicon56

Zooming in effects

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Helicon56    122
Hi, I''ve seen it loads of times in games when a camera seems to zoom in to get a better look at something, normally with sniper rifles... so does anyone knoe how it''s done? --helicon56.

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Helicon56    122
lol, i''m pretty sure it''s not done like that. it''s like it is actually zooming in, in the way that a real camera does, by enlarging a certain part of it''s view. it''s difficult to explain, but you probably know what i mean.

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WizHarDx    190
the way zooming is done in real life & in games is set the horizontal field of view smaller. As this make all objects take a larger amount of the fov & hence make objects seem larger

hope this helped
Iain

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RhoneRanger    100
In 3d grafx, there is also the zoom that occurs while looking through the scope of a rifle, or makes objects larger.

The way I acclompish this is by moving the camera closer to the objects. I get 0 performance hit this way.



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MichaelT    214
you change the field of view (frustrum) to create the zoom effect. The difference between moving the camera and changing fov is that the perspective is nearing orthogonal view (loosing perspective) So you don''t move the camera.

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MichaelT    214
Not that much more expensive I would think (I can''t be sure since in all honesty I haven''t measured it). The point is that it looks better though.

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Guest Anonymous Poster   
Guest Anonymous Poster
Uhhhh, just moving the camera closer is definitely not the way to go. What if you''re looking at a wall and you decide to zoom? Whoops, now you''ve placed the camera outside or nextdoor or something.

The proper way to do it is to lower the field of view of the camera, as someone above suggested.

-- John

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mdias    823
In DirectX you can do that this way:

float p_Zoom = 1.0f;
D3DXMATRIX ProjectionMatrix;
D3DXMatrixPerspectiveFovRH( &ProjectionMatrix, p_Zoom, 640.0f/480.0f, p_MinViewDistance, p_MaxViewDistance );

Now you only need to update the ''p_Zoom'' variable


KaMiKaZe

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Helius    122
Yes! The right way to achieve the zoom effect is altering the Fov of the projection matrix. The human Fov is near to 50 degrees, try reducing it up to 5 degrees to simulate a zoom in effect and backwards to 50 to produce a zoom out. Remember I said degrees not radians

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