stencil buffer

In the simplest case, the stencil buffer is used to limit the area of rendering (stenciling).

Render the scene again as if it were completely lit, using the stencil buffer to mask the shadowed areas.

This can be done by flagging the stencil buffer when rendering any object permitted to bloom.

Is more flexible because all of depth buffer, stencil buffer, etc. can be acquired.

In addition, shadow maps do not require the use of an additional stencil buffer, and can be modified to produce shadows with a soft edge.

Some involve two passes, and some only one; some require less precision in the stencil buffer.

Stencil buffer is modified as per glStencilOp fail.

Shadow volume (a stencil buffer technique creating shadows)

Alternatively one can give the stencil buffer a +1 bias for every shadow volume the camera is inside, though doing the detection can be slow.

The depth buffer and stencil buffer often share the same area in the RAM of the graphics hardware.

The depth fail method has the same considerations regarding the stencil buffer's precision as the depth pass method.

Typically Stencil buffer is initialized by setting depth buffer and color buffer masks to false.

The stencil buffer implementation of shadow volumes is generally considered among the most practical general purpose real-time shadowing techniques for use on modern 3D graphics hardware.

Using the depth information from that scene, construct a mask in the stencil buffer that has holes only where the visible surface is not in shadow.

Stencil buffer shadows are used as simple planar shadows, as well as blurred stencil volumes.

These shadowed areas are typically shaded after the scene is rendered to buffers by storing shadowed areas with the stencil buffer.

Examples of such layers are color buffers, transparency buffers (alpha), stencil buffers, and depth buffers.

It can clear up to four buffers (the color, depth, accumulation, and stencil buffers), so the API authors could have had it take four arguments.

A stencil buffer is an extra buffer, in addition to the color buffer (pixel buffer) and depth buffer (z-buffering) found on modern graphics hardware.

After Crow, Tim Heidmann showed in 1991 how to use the stencil buffer to render shadows with shadow volumes quickly enough for use in real time applications.

The stencil buffer and its modifiers can be accessed in computer graphics APIs like OpenGL and Direct3D.

The Elan Graphics system also implemented hardware stencil buffering by allocating 4 bits from the Z-buffer to produce a combined 20-bit Z, 4-bit stencil buffer.

More advanced usage of the stencil buffer makes use of the strong connection between the depth buffer and the stencil buffer in the rendering pipeline.

There is another potential problem if the stencil buffer does not have enough bits to accommodate the number of shadows visible between the eye and the object surface, because it uses saturation arithmetic.

Direct3D 6.0 introduced numerous features to cover contemporary hardware (such as multitexture and stencil buffers) as well as optimized geometry pipelines for x87, SSE and 3DNow!