Painter's algorithm: Difference between revisions

Revision as of 08:09, 1 April 2002

Revision as of 17:52, 12 October 2002

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'''Painter's algorithm''' is one of the simplest solution to the [[visibility problem]] in [[3D graphics]]. When projecting 3D scene into a 2D plane, at some point, you need to decide which [[polygon]]s are visible and which are hidden.

Painter's algorithm is one of the simplest

solution to visibility problem in 3D graphics.

When projecting 3D scene into a 2D plane, at some

point, you need to decide which [[polygon]]s are visible

and which are hidden.

The name "painter's algorithm" references to a silly painter who paints the distant parts of a scene at first and then covers them by those parts which are nearer. Similarly, when you want to use this algorithm in your rendering system, you have to sort all thy polygons by their depth and then paint them in this order. You will over-paint the parts that are normally not visible and thus solve the visibility problem.

The name "painter's algorithm" references to a silly painter

who paints the distant parts of a scene at first and then

covers them by those parts which are nearer. Similarly,

when you want to use this algorithm in your rendering system,

you have to sort all thy polygons by their depth and then

paint them in this order. You will over-paint the parts

that are normally not visible and thus solve the visibility

problem.

Note that this approach has several problems. What happens,

when polygon A partly covers B, B partly covers C and C partly

covers A again? Painter's algorithm will fail in this case.

Other problem is that it's very slow because the computer

needs to calculate all the intensities at all points of all

polygons even if they will be dropped out immediately, because

the polygon is not visible.

Note that this approach has several problems. What happens, when polygon A partly covers B, B partly covers C and C partly covers A again? Painter's algorithm will fail in this case. Other problem is that it's very slow because the computer needs to calculate all the intensities at all points of all polygons even if they will be dropped out immediately, because the polygon is not visible.