glStencilFunc Method

Set front and back function and reference value for stencil testing.

Namespace: Ooogles
Assembly: Ooogles (in Ooogles.dll) Version: 1.0.0.0 (1.0.0.0)

Syntax

public static void StencilFunc(
	glCompareFunc func,
	int reference = 0,
	uint mask = 4294967295
)

Public Shared Sub StencilFunc ( 
	func As glCompareFunc,
	Optional reference As Integer = 0,
	Optional mask As UInteger = 4294967295
)

public:
static void StencilFunc(
	glCompareFunc func, 
	int reference = 0, 
	unsigned int mask = 4294967295
)

static member StencilFunc : 
        func : glCompareFunc * 
        ?reference : int * 
        ?mask : uint32 
(* Defaults:
        let _reference = defaultArg reference 0
        let _mask = defaultArg mask 4294967295
*)
-> unit

Parameters

func: Type: OooglesglCompareFunc
the test function. Initial value is Always.
reference (Optional): Type: SystemInt32
(optional) value that specifies the reference value for the stencil test. reference is clamped to the range [0, 2n - 1], where n is the number of bitplanes in the stencil buffer. The initial value is 0.
mask (Optional): Type: SystemUInt32
(optional) value that specifies a mask that is ANDed with both the reference value and the stored stencil value when the test is done. The initial value is all 1's.

Remarks

Stenciling, like depth-buffering, enables and disables drawing on a per-pixel basis. Stencil planes are first drawn into using GL drawing primitives, then geometry and images are rendered using the stencil planes to mask out portions of the screen. Stenciling is typically used in multi-pass rendering algorithms to achieve special effects, such as decals, outlining, and constructive solid geometry rendering.

The stencil test conditionally eliminates a pixel based on the outcome of a comparison between the reference value and the value in the stencil buffer. To enable and disable the test, call Enable(glCapability) and Disable(glCapability) with argument StencilTest. To specify actions based on the outcome of the stencil test, call StencilOperation(glStencilOp, glStencilOp, glStencilOp) or StencilOperationSeparate(glFace, glStencilOp, glStencilOp, glStencilOp).

There can be two separate sets of func, reference, and mask parameters; one affects back-facing polygons, and the other affects front-facing polygons as well as other non-polygon primitives. StencilFunc sets both front and back stencil state to the same values. Use StencilFuncSeparate(glFace, glCompareFunc, Int32, UInt32) to set front and back stencil state to different values.

func is an enum that determines the stencil comparison function. It accepts one of eight values (see glCompareFunc).

reference is an integer reference value that is used in the stencil comparison. It is clamped to the range [0, 2n - 1], where n is the number of bitplanes in the stencil buffer.

mask is bitwise ANDed with both the reference value and the stored stencil value, with the ANDed values participating in the comparison.

Note: initially, the stencil test is disabled. If there is no stencil buffer, no stencil modification can occur and it is as if the stencil test always passes.

Note: StencilFunc is the same as calling StencilFuncSeparate(glFace, glCompareFunc, Int32, UInt32) with face set to FrontAndBack.

OpenGL API: glStencilFunc